Laserfiche WebLink
6.0 OBSERVED ItiPACTS ON THE HYDROLOGIC SYSTHMS OF THE TRAPPER!lINS <br />6.1 GROUND WATER <br />Water-quality changes in the last few years for the QR aquifer <br />are mainly due to natural variations in the recharge rate. Water- <br />level changes in QR aquifer wells GD2, GA1, and GF6, along with <br />associated backfill wells GD3 and GF11, are close to active mining <br />and have been influenced by mining activities in addition to <br />natural variations. The water levels in all of these wells rose <br />significantly in 1993. The increase is in response to several <br />factors: a wetter year (two inches more than 1992), resulting in <br />increased recharge and the reduction of dewatering activities in D <br />pit (pit pumpage and dewatering wells). These wells are located <br />near the downgradient toes of D and E pits and/or at the interface <br />of upgradient backfill and the downgradient native QR aquifer. <br />These positions tend to amplify water-level variations. <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 generally more permeable than the native aquifer which also <br />allows ground water to flow faster through the backfill material <br />resulting in more water in the aquifer at this location. The input <br />of additional water to the native aquifer at the north end (toe) of <br />the mining has decreased the effects mine dewatering has had on <br />water levels in this portion of the aquifer. <br />The water-level changes for the HI aquifer have also been <br />. influenced by variations in recharge during the last few years. <br />6-1 <br />