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Seepage Sources Within the West Pit Excavation The Division of Minerals and Geology has expressed concerns regarding the source of water for the seepage which has occurred near the West Pit Pond, specifically if the seeps are related to impoundment of water wRhin the current excavation, whether future conditions after reclamation will increase/decrease seepage, and if sealing of the coal seams is required. The factors which will affect these concerns include the orientation/elevation of the coal seams (or sandstone layers), the drain outlets, and other mine features. An in-pit ramp was previously constructed in the West Pit excavation which impounded water in the northern portion of the pR at about elevation 7085. Stratigraphic connections between the pR area and the pond area are very approximate. Based on the estimated dip ft is possible the water impoundment was theoretically connected to the observed seeps. Observations by Colowyo personnel indicated that seepage rates increased with precipitation levels. This observation, combined witfi the comparatively high precipitation amounts during the spring of 1995, indicate the most likely source of seepage is precipitation which recharges sandstone seams and creates a perched water zone above less permeable claystone/siltstone seams. In any case, the water impounded by the ramp has been removed and the ramp will be slotted and the underdrain extended through the ramp. Excavation (pit development) will soon proceed to depths (F-seam) where water which collects in the base of the West Pit excavation will seep through bedrock zones which do not outcrop above the base of the drainage or the West Pit Pond and will no longer present a concern to this area. Two drain outlets are planned, the main fill underdrain and an outlet drain where the excavation will cross East Taylor Creek. The approximate locations and elevations are shown on Fig. 1. The excess spoil fill in the East Taylor Creek area has been eliminated from the current mine plan. The underdrain (elevation = 7040± at the north edge of the West Pit excavation) and the East Taylor Creek Outlet (elevation = 6990 will provide an outlet for water which infiltrates the spoil fill, should it build up to these levels. Based upon this configuration we believe it will only be necessary to seal coal seams which are below elevation 6990. Conversely, it will not be necessary to seal coal seams which do not outcrop in the West Pit Pond area, instead passing below this area. Colowyo provided the estimated outcrop location of the YZ seam as shown on Fig. 1. The X seam is about 76 feet below the YZ seam. Based upon this, we have developed the following conclusions: 1. Coal seams below the Y2 and Y, seams will not require sealing since they pass below, and do not outcrop in the West Pit Pond area. 2. Sealing of the YZ or Y, seam could be required where they exist at elevations below 6990 feet, since the East Taylor Creek drain outlet should prevent water buildup above this level. COLOWYO COAL COMPANY L P. cttlr z~,ooi 4