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Fntnre 11{fater Inflow <br />• As the mine extends farther to the east and then north as shown in Figure 2.1.1 of the permit <br />application, it is possible that water will be encountered . Figure 4.2- 3, of the permit application, <br />shows that the saturated strata may again be encountered approximately 400 feet ahead of where <br />mining stopped in 1997. This location is neaz the eastern edge of Figure 3, Mine Map. If water <br />is once again encountered, its existence will be documented and detailed in future reports. <br />As shown on Figure 4.2-3 the saturated strata appear outcrop in the valley formed by the <br />north split of Munger Canyon. Since the strata in the azea dip at four percent to the northeast <br />water may be infiltrating the seam along the valley bottom. Any water infiltrating the strata at this <br />location will flow down dip until the aquifer is totally saturated unless there is an area where <br />water may escape. The elevation of the saturated zone would approximate the elevation of the <br />outcrop (5,600 ft) if no water flows out of the strata at a lower elevation. The elevation of the <br />existing faces is approximately 5636 ft. There aze no known springs or seeps that would allow <br />escape of the water from the zone of saturation so it can be expected that the coal seam will be <br />saturated near the outcrop elevation. <br />MUNGER CANYON MINE <br />To date there has been no water encountered by this mine; therefore, there has been no effect <br />on the hydrologic regime of the area. A current mine workings map is included as Figure 4. <br />Table 1 documents that no water was used at the mine this year. <br />• PRECIPITATION <br />Based upon Bureau of Land Management records from a rain gage in Ashford Canyon, the <br />1997 water year experienced above average amounts of precipitation, 21.40 inches. The average <br />annual precipitation since monitoring began in 1977 has been about 16.47 inches. The <br />precipitation received in September was a record high of 4.66 inches, while March was a record <br />low of 0.18 inches. As depicted on Figure 2, only four months had higher than normal <br />precipitation. The rain gage is not located at the none but about 3.5 miles north at an elevation of <br />5895 feet compared with 5610 at the portals. The daily rainfall record is detailed on Table 2 and <br />graphed on Figure 2. <br />Two major precipitation events occurred during the year. The first event occurred in early <br />August. According to measurements at the mine, the amount of precipitation was about 2 inches <br />in 24 hours. No discharge from the sediment pond was necessary since the pond was nearly dry <br />and retained the entire volume of runoff. The storm did damage some of the surface water <br />systems at the mine. In general, sediment and debris was deposited in the channels and culverts <br />and had to be removed to regain design capacity. <br />The second storm event occurred in late September. As reported ,the storm lasted five days <br />and put down a total of 5.25 inches of precipitation. The fourth day was most intense resulting in <br />2.5 inches of rain in 24 hours. The 100 yeaz event is 2.6 inches. This storm was nearly retained in <br />the pond until an additional 0.8 inches of rain occurred during the next three hours. This <br />combination of events made discharge from the pond necessary. <br />• <br />AFIR - 97 Page - 3 2 - 6 - 98 <br />