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_ - Y 06/91/1992 1: 27:01PM HVDRO 307-266-6597 P1 NNNNMNMNNNNNMNNNNNNNNNMNMMMNNNNNNNNMMNNNNMNMMNMMMNNNNNMNNNMNNNM FAX TRANSMITTAL SHEET wwwNNMNNMNNNwNYwNMwMwNwMNNMNNNwwNNNwMNwNNNwNMNMNwwwNNwNwwNNwMwN DATE: 6/01/92 TIME: 13:30 NUMBER OF PAGES NOT INCLUDING THIS PAGE: NZ TO THE ATTENTION OF: BILL HARDING TRAPPER MINE FAX PHONE: FROM: NAME: GEORGE L. HOFFMAN, HYDRO-ENGINEERING PHONE: 1-266-6597 FAX PHONE: SAME AS ABOVE; CALL TO NOTIFY FIRST Responses to Trapper Mine Questions: Response D. 1. Nater-level elevations in each of the paired backfill downgradient aquifer monitoring wells show a very flat gradient between the backfill aquifer and the water level downgradient of the mining. Monitoring well GF-4 is located in the I coal seem. The head in this aquifer is slightly less than the head to the south in the backfill aquifer at well GF-7. The head at GF-4 would he expected to be less then 6493 prior to raining, based on the pre- roine water-level elevation in HI aquifer well GB-5. The pre-mine water level in well GF-4 would be expected to be less than the pre- mine level of 6465 ft-msl that was observed in sell GB-5. The higher permeability (approximately 5 times larger than at GF-4) in the backfill aquifer at GF-7 is thought to allow the water to move more readily down to the aquifer downgradient of the mining at GF- 4. iwo pairs of wells completed in the backfill end the QR -."'aqu.ifer downgradient of mining are monitored. These two sites are monitored at GD-2/GD-3 and GF-6/GF-11. The heads in the downgradient wells are essentially the same as the water-level elevations in the upgradient backfill aquifers at these two locations. The pre-mine water level elevation in QR well GA-1 was approximately 6670 ft-msl. This water-level elevation indicates that the present water-level elevation at GF-6 is probably higher than the water-level elevation at the QR aquifer in this area prior ~ ~;