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2012 AHR <br />long the mine will remain idle. <br />McClane & Munger Canyon Mines <br />Page 2 <br />As required by stipulations, a mine map for McClane Canyon showing important <br />hydrologic features is included as Figure 3. Seepage into the mine is nearly all <br />from the areas mined to the north of the East Mains. Water from seeps <br />accumulates in the east end of the East mains. In response to comments made <br />by the Division regarding the 1995 annual hydrologic report, Figure I - Water <br />Sampling Locations, is enclosed. Figure 1 is a line diagram of the drainages and <br />water sampling locations that was derived from Figure 4.2 -2 of the McClane <br />Canyon Mine permit. <br />Mine Water Inflow /Discharge. <br />Appendix N of the permit application indicates the rate at which the saturated <br />coal ribs are exposed should govern the maximum mine inflow rate. A five entry <br />system exposes 1,480 lineal feet of rib per 100 feet of advance assuming 80 foot <br />square pillars. That same 100 feet of development produces 5,400 tons of coal <br />assuming an eight foot mining height. Based upon the k factor of 0.11 feet per <br />day, it takes about one year to dewater an 80 foot square pillar (40 feet / 0.11 <br />feet per day). Therefore, exposed coal ribs contribute to mine inflow for one <br />year. At an annual production rate of 0.3 million tons per year, using this five <br />entry system, a total of 5,500 feet of development would be required. This would <br />expose 81,000 [(1,480)(5,500) /100] feet of rib. This amount of exposed rib <br />would produce an estimated maximum mine inflow as follows q = kia = (0.11) <br />(81,000 x 8) (0.05) = 3,600 cubic feet per day = 20 gpm. <br />Water was discharged from the mine during the August and September 2012. <br />During the hot summer months the mine discharge is utilized to water roads. <br />Flows into the mine are estimated in Table 1. Previous hydrologic reports have <br />shown the inflow of water to the mine can be attributed to dewatering of a <br />perched aquifer as well as surface water infiltration along the faults of the <br />graben. During the mid 1980's, a clear picture of mine water inflows was <br />obtained because water collected in the faces was regularly pumped to outfall <br />002 and discharged. The quantity of water discharged was recorded on a meter <br />and correlated with precipitation. The steady decrease in the amount of water <br />pumped from the mine during the idle years is evidence of the creation of a <br />dewatered zone in the saturated coal strata. This decrease also provides <br />evidence there is little communication with the comparatively large aquifer within <br />the East Salt Creek alluvium across the west fault of the graben. <br />When mining resumed, additional area in the saturated portion of the graben <br />was exposed, increasing the flow of water into the mine. The inflow of water <br />went from a low of 0.80 gpm in 1988 to a high of 3.87 gpm in 1990. Water <br />flowing down dip into the faces was pumped to the sump and used in the mining <br />