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r~ <br />U <br />2.1 GRUUND WATER-LEVEL CHANGES <br />2.1.1 SUMMARY <br />Water-level r_hanges in we 115 GD2 and GE6 ar=~ thought tr be <br />I <br />mainly attributed to natural variation in recharge to thel 9k <br />.aquifer. Some of the water-level changes could be a result of <br />mining. Water-level responses in wells GD2 and (aF6 .are ve}•Y <br />similar to responses in well GP5 (9R aquifer well) that is distant <br />to anY active mining in the 9R seams and reflects natural <br />variations. Water-level chances in 9R well, GA1, have beiome <br />steady in 1992. Some of the r_hange in well GA1 is likel.v dui to <br />the proximity of E and D pit mining activities. <br />Upgradient mining can cause water-level rises in wells <br />downgradient of the mining by allowing ground water to flow to the <br />downgradient end of mining quicker. Also, the backfill aquifers <br />are more permeable than the native aquifer which also allows griund <br />water to flow faster through the backfill material resulting, in <br />more water to the aquifer at down-dip pit toes. This input of <br />additional water to the native aquifer at the north end (toe) of <br />the mining has probably decreased the effects that mine dewater~ing <br />has had on water levels in this portion of the aquifers. <br />Water levels in the uphill portion of the backfill areas 'are <br />depressed compared to pre-mine levels and are not likely to eer <br />rer_over. Map Z-1 shows that the levels in the backfill ;and <br />downgradient aquifers are close. Upgradient and downgradient w11 <br />pairs GD3-GD2 and GF11-GE6 contain water levels that are very close • <br />;_~ <br />