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0 2008 AHR McClane & Munger Canyon Mines Page 3 <br />Source of Water Inflow <br />As detailed in previous reports, the water flowing into the mine seems to be a mix of <br />water infiltrating the graben along the faults and water in the coal seam. The zone of <br />saturation of the coal seam was initially estimated using the results of exploration drilling. <br />The drilling indicated that holes in the McClane graben were dry; specifically, holes <br />7-15-3 and 7-21-1. <br />Additionally, a piezometer installed down dip from the mine outside of the graben has not <br />realized water to date. Since the piezometer is down-dip and is dry it is apparent water <br />flowing into the mine is from a perched aquifer in the area of the coal mine. <br />The water within the perched aquifer flowing into the mine probably comes from surface <br />water infiltration along the faults east and west of the mine. Both faults have ephemeral <br />drainages crossing their surface trace. These faults may be one source of recharge to <br />the perched aquifer. The water then infiltrates the coal seam which has become <br />saturated over time. This assumption is supported by the previously documented cyclical <br />nature of water inflow corresponding with periods of precipitation. <br />Future Water Inflow <br />All future mine development is in the saturated zone so mine inflows/seeps should be <br />relatively continuous with the inflow slowly increasing. However, most of the water <br />generated in the mine comes from the sealed areas in the north. Apparently water in the <br />• saturated 2nd East Mains coal has over time drained into the East Mains. <br />As shown on Figure 4.2-3, the saturated strata appear to outcrop in the valley formed by <br />the north split of Munger Canyon. Since the strata in the area dip at four percent to the <br />northeast water may be infiltrating the seam along the valley bottom. Any water infiltrating <br />the strata at this location will flow down dip until the aquifer is totally saturated unless <br />there is an area where water may escape. The elevation of the saturated zone would <br />approximate the elevation of the outcrop (5,600 ft) if no water flows out of the strata at a <br />lower elevation. There are no known springs or seeps that would allow escape of the <br />water from the zone of saturation so it can be expected the coal seam will be saturated <br />near the outcrop elevation. <br />Munger Canyon Mine <br />The Munger Mine has been sealed and the disturbed areas were graded and seeded in <br />2007. There was no water encountered in mine; therefore, there has been no effect on <br />the hydrologic regime of the area. The current mine workings are shown on Figure 4. <br />Precipitation <br />Based upon Bureau of Land Management records from a rain gage in Ashford Canyon, <br />the 2008 water year experienced 15.7 inches of precipitation compared to average <br />precipitation of 17.9 inches. The rain gage is not located at the mine but about 3.5 miles <br />north at an elevation of 5895 feet compared with 5610 at the portals. The daily rainfall <br />record is detailed on Table 2. The greatest 24 hour precipitation event during the water <br />year, 1.25 inches, occurred on January 5cn. Figure 2 presents a graphical comparison of <br />• the 2008 total monthly precipitation and the average monthly precipitation for the period <br />1977 through 2008. Precipitation data are obtained from the BLM. <br />Rev. 08/09