1998-01-01_REPORT - C1981035 - Laserfiche WebLink

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can be accomplished using the mine scales and the known volume of a front end loader bucket. This information can then be used in establishing the bond estimate. In addition to the physical properties, a chemical analysis of[he topsoil must be performed to determine the quantity of fertilizer that will be needed to assure successful growth of vegetation during final reclamation. Five Year Waste Pile A revised estimate of 500o cubic yards of waste rock production annually was used in estimating the elevation of the 5-year waste pile. Beginning with the existing waste rock volume, approximately 25,000 cubic yards, and adding the annual increment, results in a required 5-year volume of 50,000 cubic yards. This corresponds to a pile height of 75 feet (elevation 7490). The boundary of the 5- year pile is shown on the accompanying design drawing. In addition, the volume of cover material (fill and topsoil) for the 5-year pile was estimated at 7000 cubic yards. Of this, the mina operator estimated chat they currently have enough cover stockpiled to accommodate the existing pile (about 4800 cubic yards of cover). A location for the 5-year cover storage pile (7000 cubic yards) is shown on the plan drawing. drainage Features Enlargement of the waste pile will require modification of the drainage intercept ditches on both the north and south side of the pile. In addition the - sedimentation ponds will be altered to accommodate the increased contaminated runoff volumes. All ditches and pipes are sized for the 200 year event and the ponds for the �O year event. Please refer to the drainage report (revised July t997), and the accompanying design drawings for details. The Eastside drainage channel will be moved from its existing location, to the north against the natural hill slope. As the waste bank increases in elevation the ditch will move up the hillside. Ai the top of the sloping pile faced the channel will intersect an armored channel that will flow down the front face of the waste pile. These two ditches will route uncontaminated water to the clear water tliversion system. A similar set of intercept ditches on the south side of the pile will collect contaminated runoff from the pile and some clear water from the adjacent hillside and route it to the sedimentation ponds. Please refer to the design drawings and the drainage report for details. Underdrain An untlerdrein system for the waste pile is required by the regulations. The purpose is to intercept water which originates either forth precipitation infiltration through the waste pile surface or from the interception of groundwater at the pile- January 1998