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2.2 GROUND WATER-LEVEL ELEVATION (PIEZOMETRIC MAP SUMMARY) <br />Hydro-Engineering developed three piezometric maps to show the water level flow <br />patterns for the QR, HI and 3rd White Sandstone aquifers at Trapper Mine. Water levels from the <br />Fall of 2008 were used to develop these maps. The third quarter water levels were used because <br />two levels from the fourth quarter were questionable. <br />Map No. 2-1 presents the water-level elevations for the QR aquifer. The water-level <br />elevation is presented for the QR wells: GD-2, GF-6 and GP-5 and backfill wells GD-3 and GF-11. <br />The ground-water flow in the QR aquifer is mainly to the north. Mining has only affected the QR <br />aquifer close to the D, E, F, G and Z pits by causing drawdowns very near the pit edges. The <br />installation of backfill wells GD-3 and GF-11 has defined the depressed elevations in the backfill <br />areas. The wells in this area experienced larger water level rises during 2008. The water level <br />increases in 2008 are likely due to more recharge in recent years. The backfill water levels will <br />likely stabilize lower than the pre-mine levels due to the increased permeability of the backfill • <br />aquifer, which allows the water in the aquifer to be transmitted at a lower gradient. The gradient <br />calculated for the backfill near D pit is less than 0.05 ft/ft, compared to the undisturbed gradient of <br />0.12 ft/ft. The heads in the northern end of the backfill aquifer will likely recover above the pre- <br />mine level. Backfill springs are not expected to develop near the northern end of the QR backfill <br />because backfill water levels would have to recover greater than a few tens of feet to reach the <br />lower land surface elevations. Table 2-1 of the 1990 Annual Hydrologic Report (Hydro- <br />Engineering, 1991) presents aquifer properties at Trapper Mine. The permeabilities from the <br />backfill aquifers are significantly greater than the coal aquifers that they replace. <br />The water-level contours extend through the pit areas for the F, G and Z pits because the <br />R seam was not mined in these pits and therefore the QR aquifer still exist under these pit floors. <br />Some drawdown would be expected in these areas of the QR aquifer and are indicated by the <br />contours. 0 <br />Trapper Mining Company 2-8 <br />2008 Annual Report