2008-09-17_REVISION - M1980244 (28)

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• In summary, the pumping test performed to evaluate the mechanisms of flow in the deep ground water system in the Precambrian rocks in Grassy Valley identified slight connection along the axis of the valley, no connection across the axis of the valley, and slight serial connection vertically (i.e. connection where the deeper water is influenced by pumping in the shallow bedrock, but not vice-versa). Due to the failure of the completion of GVMW-15A, CC&V was unable to perform the planned pumping of this well to evaluate whether there is any effect on shallow wells due to pumping deep wells. The bedrock in Grassy Valley is likely fractured similarly to the Precambrian rock recovered by geotechnical core drilling conducted in the eastern wall of the proposed Wildhorse Extension portion of the East Cresson Mine. This rock shows that fracture frequency is similar to that identified in the volcanic rock of the diatreme, but there is a preferential fracture orientation along the schistosity of the laminated rocks within the Precambrian rockmass. As the intact granitic rocks are essentially impermeable, all water flow in the Precambrian rocks must pass along the rock structures: joints, faults, and schistosity planes. Mining as proposed in the MLE Project Amendment will have no effect on the transmission of water from the alluvial aquifer to the bedrock aquifer, because the bedrock underneath the alluvial aquifer is not saturated or pressurized with ground water for a significant depth • below the stream and the riparian areas. This is demonstrated by review of all 35 wells that have been drilled and completed in the bedrock in Grassy Valley. The behavior of the aquifer system can be seen very clearly in the nest of wells that are located approximately opposite the proposed northern wall of the East Cresson Mine (Wildhorse Extension). The well information is summarized in Table 4. Table 4 - Water Conditions in Section through PZ-3 • o i7L to '0 46 2 U) c l LL EN c =E ?+?. O w c d o .0 0 .0 MO O 0 II: 0' 2 m c7 w ? CO H LL. 2 GVMW-16B 68 102 Xbg 0 10177 10075 10105 30 PZ-3 10 20 Qal 83 10105 10085 10088 3 GVMW-14C 484 612 Xms 364 10089 9477 9486 10 GVMW-14B 77 98 Xgd 369 10089 9991 9990 -1 GVMW-13A 490 600 Xgd 845 10166 9566 9696 130 GVMW-13B 430 550 Xgd 854 10161 9611 9637 26 GVMW-13C 32 50 Xbs 859 10159 10109 10111 2 GVMW-11A 380 500 Tph 1318 10278 9778 9778 0 GVMW-11 B 24 50 Tphbx 1329 10279 10229 10230 1 Note: Qal = Alluvium; X = Precambrian granite, schist, and gneiss; T = tertiary volcanics .1?_