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Source of Water Inflow <br />• As detailed in previous reports, the water flowing into the mine <br />seems to be a mix of water infiltrating the graben along the faults <br />and water in the coal seam. The zone of saturation of the coal seam <br />was initially estimated using the results of exploration drilling. <br />The drilling indicated that holes in the McClane graben were dry; <br />specifically, holes 7-15-3 and 7-21-1. Additionally, a piezometer <br />installed downdip from the mine outside of the graben has not <br />realized water to date. Since the well is down-dip and is dry it is <br />surmised that the water flowing into the mine is from a perched <br />aquifer in the area of the coal mine. <br />The water within the perched aquifer flowing into the mine probably <br />comes from surface water infiltration along the faults east and west <br />of the mine. Both faults have ephemeral drainages crossing their <br />surface trace near the mine and may receive water from the <br />drainages. The water then infiltrates the coal seam which has <br />become saturated over time. This assumption is supported by the <br />previously documented cyclical nature of water inflow corresponding <br />with periods of precipitation. <br />MUNGBR CANYON MINE <br />To date there has been no water encountered by this mine; therefore, <br />there has been no effect on the hydrologic regime of the area. A <br />current mine workings map is included as Figure 2. Table 1 <br />documents that no water was used at the mine this year. <br />• PRECIPITATION <br />Based upon Bureau of Land Management records from a rain gage in <br />Ashford Canyon, the 1992 water year experienced above average <br />amounts of precipitation. About 25.51 inches of precipitation was <br />Table 2 gives the daily precipitation record for the 1993 water year <br />and Table 3 contains monthly totals since 1977 for the Ashford <br />Canyon site. January with 5.02 inches and February with 4.47 inches <br />were especially wet. If these months had received the their normal <br />precipitation, 3.47 inches, the precipitation for the year would <br />have been nearly identical to the average year, 19.69 inches. The <br />records for the Ashford Canyon rain gage do not give a precise <br />record of the precipitation at the mines. Localized thunderstorms <br />and may only effect one of the many canyons in the area. <br />Two storm events, on October 30, 1992 and March 27, 1993 were in <br />excess of the 10 year 24 hour storm event. Measurements of <br />precipitation at the McClane Mine indicate that these events were <br />also excessive at the mine. The event in October 1992 occurred just <br />after the sedimentation pond had been cleaned and put about five <br />feet of water in the dry pond. This was a short duration nighttime <br />storm and was not sampled. On the weekend of March 27 over 3 inches <br />of rain was measured at the mine site. Since the storm occurred <br />over the weekend, no samples were collected. <br />• <br />Page - 3 1/19/94 <br />