2007-03-16_REPORT - C1981010 (12)

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post -mine levels under the same conditions may be higher. Springs are not expected to develop at the north end of the D and F pits. The water -level changes for the HI aquifer have generally been influenced less by slightly less than average recharge during the previous seven years prior to the above average precipitation in 2005 and 2006. The mining upgradient of HI well GF-4, which occurred several years ago, has been long enough in the past to allow water levels to fully recover. The water levels in this HI aquifer well seem to be varying only slightly with changes in recharge rates. Water levels in this well were overall slightly higher in 2006 with the above normal precipitation. The elevation of the backfill springs likely limits the head buildup in the backfill aquifer, which, in turn, limits the maximum head in the downgradient coal aquifer. Fairly steady water -level responses were observed in the two backfill equivalent HI aquifer wells GF -5 and GF -7. Water levels seem to have reached recovered levels in these two wells. The development of backfill springs may limit the maximum water level in some of these areas of the A pit. The water levels in the three GE wells stabilized in approximately 1990. This is thought to be due to the length of time since dewatering stopped at the adjacent underground operation. Gradually declining water levels were observed in these three wells with the above normal precipitation. Water levels in the backfill areas are depressed and are not likely to ever recover to pre - mine levels except near the northern end of the mine area. Map 2 -1 shows that the levels in the backfill and downgradient aquifers are similar. Well pairs GD -3 & GD -2 and GF -11 & GF -6 present water levels that are very similar in water -level elevation for the backfill and downgradient QR aquifer well. Mining is significantly increasing the permeability of the backfill aquifers which Trapper Mining Company 6-2 2006 Annual Report