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. 2006 AHR McClave & Munger Canyon Mines Page 2 <br />Mine Water Inflow/Discharge <br />Appendix N of the permit application indicates the rate at which the saturated coal ribs <br />are exposed should govern the maximum mine inflow rate. A five entry system <br />exposes 1,480 lineal feet of rib per 100 feet of advance assuming 80 foot square pillars. <br />That same 100 feet of development produces 5,400 tons of coal assuming an eight foot <br />mining height. Based upon the k factor of 0.11 feet per day, it takes about one year to <br />dewater an 80 foot square pillar (40 feet / 0.11 feet per day). Therefore, exposed coal <br />ribs contribute to mine inflow for one year. At an annual production rate of 0.3 million <br />tons per year, using this five entry system, a total of 5,500 feet of development would <br />be required. This would expose 81,000 [(1,480)(5,500)/100] feet of rib. This amount of <br />exposed rib would produce an estimated maximum mine inflow as follows q = kia = <br />(0.11) (81,000 x 8) (0.05) = 3,600 cubic feet per day = 20 gpm. <br />Water was discharged from the mine during the reporting period. During the hot <br />summer months the mine discharge can be utilized to water roads. Flows into the mine <br />are estimated in Table 1. Previous hydrologic reports have shown the inflow of water to <br />the mine can be attributed to dewatering of a perched aquifer as well as surface water <br />infiltration along the faults of the graben. During the mid 1980's, a clear picture of mine <br />water inflows was obtained because water collected in the faces was regularly pumped <br />• to outfall 002 and discharged. The quantity of water discharged was recorded on a <br />meter 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 dewatered <br />zone in the 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 the <br />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. <br />A small amount of water was trucked to the mine for road dust suppression starting in <br />October 1999 prior to production. When production resumed in February 2000 the <br />demand increased to approximately 373,000 gallons per month. In April 2000 water <br />started seeping from the mining faces developing to the east. To keep up with production <br />demands, a sump was established and the section was moved to the south. The water in <br />the faces is currently pumped to the sump and again used in the mining process for dust <br />control. During 2006 the inflow of water into the mine is estimated to be approximately 16.4 <br />gpm based on the mine's demand for water and the amount of water discharged and <br />consumed for dust suppression. This compares favorably with the 20 gpm estimate <br />provided above. Table 6 shows quality results of mine discharge sampling., <br />~J <br />