REP01925 - Laserfiche WebLink

Home Browse Search

2001 AHR McClane & Munger Canyon Mines Page 2 Mine Water Inflow/Discharge No water was discharged from the mine and flows into the mine are estimated in table 1. Previous hydrologic reports have shown the inflow of water to the mine can be attributed to dewatering of a perched aquifer as well as surface water infiltration along the faults of the graben. During the mid 1980's, a clear picture of mine water inflows was obtained because water collected in the faces was regularly pumped to outfall 002 and discharged. The quantity of water discharged was recorded on a meter and correlated with precipitation. The steady decrease in the amount of water pumped from the mine during the idle years is evidence of the creation of a dewatered zone in the saturated coal strata. This decrease also provides evidence there is little communication with the comparatively large aquifer within the East Salt Creek alluvium across the west fault of the graben. When mining resumed, additional area in the saturated portion of the graben was exposed, increasing the flow of water into the mine. The inflow of water went from a low of 0.80 gpm in 1988 to a high of 3.87 gpm. in 1990. Water flowing down dip into the faces was pumped to the sump and used in the mining process for dust control. On April 27, 1990, Section 001 was abandoned and sealed. A small amount of water was trucked to the mine for supply road dust suppression starting in October 1999 prior to production. When production resumed in February 2000 the demand increased to approximately 373,000 gallons per month. In April 2000 water started seeping from the mining faces developing to the east. To keep up with production demands, a sump was established and the section was moved to the south. These seeps from the East faces are now pumped to the sump and again used in the mining process for dust control thus reducing the amount of water trucked to the mine. The inflow of water in the East faces is estimated to be approximately 8.33 gpm based on the mine's demand for water. Table I gives a month by month total of the water trucked to McClane Canyon, Table 6 gives quality results of mine inflowlseep sampling. As discussed in previous reports, the area in the mine that experienced an inflow of water was sealed in 1990. No water has been produced in other areas of the mine since then. In July of 1992 all areas to the north of the East Mains were sealed and are now inaccessible. Figure 3, McClane Mine Map shows the location of the seals; as well as, the area of the mine that is not accessible. The sealed area is lower in elevation than accessible areas of the mine but is undoubtedly still experiencing an inflow of water. The volume of the portion of the mine behind the seals is equivalent to about 124 million gallons. At the rate of inflow being experienced in 1990, 3.9 gallons per minute, it would take about 60 years for the sealed area to fill with water. Only then will the mine realize a detectable inflow of water from the areas that had been making water previously.