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2.1 GRl)UND WATER-LEVEL CH6NGES • <br />2.1.1 :iII!ffiARY <br />Water-level changes in wells GD2 and GF6 are thought to be <br />mainly attributed to natural variation in re:harge to the QR <br />aquifer. Some of the water-level changes could be a result of <br />mining. Water-level responses in wells GD2 and GF6 are very <br />similar to responses in well GP5 (QR aquifer we1L) that is distant <br />to any active minir:g in the QR seams and reflects natural <br />variations. Water-level changes in QR well, GA1, have continued to <br />decline in 1991 similar to the natural declint: in QR well GP1. <br />Some of the change in well GA1 is likely due to the proximity of E <br />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 ground <br />water to flow faster through the backfill material resulting in <br />more water to the aquifer at down-dip pit toe:a. This input of <br />additional water to t:he native aquifer at the t:orth end (toe) of <br />the mining has probably decreased the effects that mine dewatering <br />has had on water levels in this portion of the :aquifers. <br />Water levels in the backfill areas are dep:^essed compared to <br />pre-mine levels and are not likely to ever recover. Map 2-1 shows <br />that the levels in the backfill and downgradient aquifers are <br />close. Upgradient anti downgradient well pairs G);3-GD2 and GF11-GF6 • <br />2-2 <br />