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• 1999 AHR McClane & Munger Canyon Mines Page 2 <br />saturated coal strata. This decrease also provides evidence there is little <br />communication with the comparatively large aquifer within the East Salt Creek alluvium <br />across the west fault of the graben. <br />When mining resumed, additional area in the saturated portion of the graben was <br />exposed, increasing the flow of water into the mine. The inflow of water went from a <br />low of 0.80 gpm in 1988 to a high of 3.87 gpm. in 1990. Water flowing down dip into <br />the faces was pumped to the sump and used in the mining process for dust control. On <br />April 27, 1990, Section 001 was abandoned and sealed. Since then, all water <br />necessary for operations has been trucked to the mine. Table I gives a month by <br />month total of the water trucked to McClane Canyon. <br />As discussed in previous reports, the area in the mine that experienced an inflow of <br />water was sealed in 1990. No water has been produced in other areas of the mine <br />since then. In July of 1992 all areas to the north of the East Mains were sealed and are <br />now inaccessible. Figure 3, Mine Workings, shows the location of the seals and the <br />area of the mine that is not accessible. The sealed area is lower in elevation than <br />accessible areas of the mine but is undoubtedly still experiencing an inflow of water. <br />The volume of the portion of the mine behind the seals is equivalent to about 124 <br />million gallons. At the rate of inflow being experienced in 1990, 3.9 gallons per minute, <br />it would take about 60 years for the sealed area to fill with water. Only then will the mine <br />realize a detectable inflow of water from the areas that had been making water <br />previously. <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 <br />drilling. The drilling indicated that holes in the McClane graben were dry; specifically, <br />holes 7-15-3 and 7-21-1. <br />Additionally, a piezometer installed down dip from the mine outside of the graben has <br />not realized water to date. Since the piezometer is down-dip and is dry it is apparent <br />that the water flowing into the mine is from a perched aquifer in the area of the coal <br />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 <br />cyclical nature of water inflow corresponding with periods of precipitation <br />• <br />