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III IIIIIIIIIIIIIIII <br />999 <br />• 1.0 INTRODUCTION Doc Date:1 211 112 0 01 <br />This report presents the ground-water and surface-water monitoring results for <br />Trapper Mine for 1996. Significant mine activities during 1996 include continued expansion <br />of the Ashmore (A), Derringer (D) and Hawken (H) pits and an increase in dewatering well <br />pumpage in D pit. Dewatering was conducted in the D, A and H pits in 1996. Construction <br />of an additional NPDES site, 017 (Oak Gulch), was begun in the Fall of 1995 and was <br />completed in 1996. <br />Ground-water monitoring of the aquifers associated with Trapper Mine started in <br />1974. The ground-water flow regime has been divided into the major sandstones and <br />coal/adjacent sandstone aquifers. This division of the aquifer systems was selected at clay <br />and shale units which have the potential to retard vertical movement. A tan pull-out index <br />presents the schematic of the aquifer units at Trapper on one side and the basic well data <br />table on the other. It is suggested moving this index sheet to the section of the report being <br />reviewed. Aquifer properties are presented in Tabie 2-1 of the 1990 Annual Hydrologic <br />Report. <br />The Twenty Mile Sandstone is the lower-most aquifer monitored at Trapper Mine. <br />The U coal seam and adjacent sandstones are the second aquifer monitored. The Q and <br />R coal seams and sandstone between these two coal seams have been labeled the QR <br />aquifer. This is one of the major aquifers of interest because D, E, and C pits have mined <br />the Q and R coal seams, currently only the D pit mines these seams. The K, L, and M coal <br />seams and the sandstones which are stratigraphically in this interval are called the KLM <br />aquifer. D pit also mines the L seam. The KLM aquifer is above the QR aquifer, but below <br />~~ <br />1-1 <br />