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<br />during the summer of 1986. The 2122 mg/1 represents discharge <br />under previously disturbed conditions (ie: prior to previous <br />permit issuance). A percentage of the dissolved constituents will <br />precipitate when the water is discharged as spoils springs. <br />Therefore, the predicted quality of the spoil aquifer discharge <br />appears to be substantiated. In the Moffat Area, where mining has <br />not yet occurred, TDS levels of the discharge are estimated to <br />increase from base conditions (570 mg/1) to 2290 mg/l. The <br />discharges leaving the Moffat Area and West Ridge will enter the <br />east bank alluvium, prior to discharging to Trout Creek. <br />Pittsburg & Midway will not mine within the Oak Creek drainage, <br />therefore, the addition of poor quality spoil aquifer discharges to <br />the creek will not occur. Minor amounts of dissolved constituents <br />could be added to the Oak Creek alluvial aquifer system due to <br />surface disturbance at the office/loadout area. However, due to <br />extensive previous mining in this drainage, and the limited amount <br />of surface disturbance, the Edna Mine operations will not <br />significantly impact the aquifer. Monitoring data collected during <br />the past permit term substantiate this conclusion. Monitoring of <br />the alluvial aquifer has not detected significant degradation of <br />the water quality, nor depletion of the aquifer itself. <br />III. Topsojl <br />A. The Division is proposing to grant a variance from topsoil removal <br />in accordance with Rule 4.06.2(2)(a) for steep slope areas of the <br />eastern portion of the Moffat Area. Topsoil will be redistributed <br />on the area. Some portions of the West Ridge Area were mined prior <br />to August 3, 1977, and no topsoil was salvaged. Available spoil <br />materials will be seeded. Steep slope variances were also granted <br />for portions of the West Ridge Area. Details on these variances <br />can be found in Section 4.3.1 and in Exhibits 4.3-1 and 2-3.1 of <br />the permit application. <br />B. The Division previously waived the requirement for clearing of <br />vegetative cover prior to topsoil removal. The applicant has <br />demonstrated that inclusion of vegetative material in salvaged <br />topsoil is necessary or desirable to ensure soil productivity <br />consistent with the post-mining land use. The operation utilizes a <br />rotoclear technique for removal of vegetation. The rotoclear <br />method chops standing vegetation, which is then included in <br />salvaged topsoil. <br />IV. Sealing of Drilled Holes and Underground Openings <br />A. The Division will require that each hole, well or other underground <br />opening be capped, sealed, backfilled, or otherwise properly <br />managed (4.07.3). <br />-26- <br />