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2012 AHR <br />McClane & Munger Canyon Mines <br />Page 3 <br />process for dust control. On April 27, 1990, Section 001 was abandoned and <br />sealed. <br />A small amount of water was trucked to the mine for road dust suppression starting <br />in October 1999 prior to production. When production resumed in February 2000 <br />the demand increased to approximately 373,000 gallons per month. In April 2000 <br />water started seeping from the mining faces developing to the east. To keep up <br />with production demands, a sump was established and the section was moved to <br />the south. The water from the east end of the East Mains is pumped to a sump and <br />used in the mining process for dust control. Table 1 shows the water balance for <br />water year 2012. As shown in Table 1, water was used to water the roads, and <br />toward the end of the water year, began discharging. The mine discharged in the <br />fourth quarter of 2012 and Table 6 shows quality results of mine discharge <br />sampling. <br />As discussed in previous reports, the area in the mine that experienced an inflow <br />of water was sealed in 1990. In July of 1992 all areas to the north of the East <br />Mains within the graben were sealed and are now inaccessible. Figure 3, <br />McClane Mine Map shows the location of the seals; as well as, the area of the <br />mine that is not accessible. The sealed area is lower in elevation than accessible <br />areas of the mine but is undoubtedly still experiencing an inflow of water. The <br />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 <br />minute, it would take about 60 years for the sealed area to fill with water. <br />Source of Water Inflow <br />As detailed in previous reports, the water flowing into the mine seems to be a <br />mix of water infiltrating the graben along the faults and water in the coal seam. <br />The zone of saturation of the coal seam was initially estimated using the results <br />of exploration drilling. The drilling indicated that holes in the McClane graben <br />were dry; specifically, holes 7 -15 -3 and 7 -21 -1. <br />Additionally, a piezometer installed down dip from the mine outside of the graben <br />has not realized water to date. Since the piezometer is down -dip and is dry it is <br />apparent water flowing into the mine is from a perched aquifer in the area of the <br />coal mine. <br />The water within the perched aquifer flowing into the mine probably comes from <br />surface water infiltration along the faults east and west of the mine. Both faults <br />have ephemeral drainages crossing their surface trace. These faults may be <br />one source of recharge to the perched aquifer. The water then infiltrates the <br />coal seam which has become saturated over time. This assumption is supported <br />by the previously documented cyclical nature of water inflow corresponding with <br />periods of precipitation. <br />