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1.0 INTRODUCTION <br />This report presents the ground-water and surface-water monitoring results for Trapper <br />Mine for 1994. Significant mine activities during 1994 include continued expansion of the Ashmore <br />(A), Derringer (D) and Hawken (H) pits and a decrease in dewatering well pumpage in D pit. An <br />additional NPDES Site, 016 (Sage Gulch) was installed in October. <br />Ground-water monitoring of the aquifers associated with Trapper Mine started in 1974. <br />The ground-water flow regime has been divided into the major sandstones and coal/adjacent sandstone <br />aquifer. This division of the aquifer systems was selected at clay and shale units which have the <br />potential to retard vertical movement. A blue pull-out index presents the schematic of the aquifer units <br />at Trapper on one side and the basic well data table on the other. It is suggested moving this index <br />sheet to the section of the report being reviewed. Aquifer properties are presented in Table 2-1 of the <br />1990 Annual Hydrologic Report. <br />• The Twenty Mile Sandstone is the lower-most aquifer monitored at Trapper Mine. The <br />U coal seam and adjacent sandstones are the second aquifer monitored. The Q and R coal seams and <br />sandstone between these two coal seams have been labeled the QR aquifer. This is one of the major <br />aquifers of interest because D, E, and C pits have mined the Q and R coal seams, currently only the D <br />pit mines these seams. The K, L, and M coal seams and the sandstones which are stratigraphically in <br />this interval aze called the KLM aquifer. D pit also mines the L seam. The KLM aquifer is above the <br />QR aquifer, but below the HI aquifer. The H and I coal seams and sandstone between these two coals <br />have been termed the HI aquifer and has been mined in the A, B, and C pits, currently only the A pit <br />mines the H and I coal seams. The 3rd White Sandstone (G coal and sandstone below) and 2nd White <br />(F coal and sandstone below) Sandstone are monitored at seven locations. H pit currently mines the <br />. G coal seam. The Lewis Shale is monitored at one location. The Johnson and Pyeatt Gulch alluvial <br />1-] <br />