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<br /> <br />Second Adequacy Review 2 9/8/95 <br />Weber Pit 2 M-95-056 <br />Exhibit C of the submitted Mine Plan shows topsoil stockpiles to be located along the north and <br />northeast perimeter of the affected area. Locating the topsoil stockpiles above the highwall, as <br />depicted on Exhibit C, will require that the highwall not approach closer than 50 feet from the <br />stockpiles to allow adequate material for a balanced cut and fill. Should the highwall approach <br />closer than 50 feet to the topsoil stockpiles located above the highwall, DMG will recalculate the <br />amount of financial warranty since the balanced cut and fill method of backfilling the highwall will <br />not be possible. Recalculation of the financial warranty to account for other methods for <br />backfilling the highwall will result in a substantial increase in backfilling cost. <br />RECLAMATION PLAN <br />DMG approves the submitted seed mix. The approved seed mix is to include Big bluegrass, <br />Smooth brome, Hard fescue, Western wheatgrass, Timothy, Russian wildrye, and Birdsfoot trefoil. <br />DMG's recommendation to include shrub species remains as a recommendation to aid in erosion <br />resistance and provide grater diversity in revegetation. Please note that soil stability and vegetation <br />diversity are criteria used to measure the success of reclamation efforts and to determine release of <br />financial warranty. <br />The mining and reclamation plans states that several sediment basins will remain on the pit floor as <br />permanent sources for livestock water. The post mining land use is rangeland, stock ponds <br />enhance the quality of rangeland; however, DMG is concerned that the permanent upland <br />diversions, proposed in the adequacy response letter dated 8/31/95, will divert flow around the <br />affected area resulting in perpetually dry ponds. The adequacy response letter dated 8/31 /95 stated <br />that, ]500 feet of upland diversion ditch would be constructed to diver[ upland flow around the <br />reclaimed slopes. DMG's previous recommendation to construct erosion resistant channels in the <br />3H:1V reclaimed slopes, would direct drainage from the upland watersheds to the stock ponds <br />located on the reclaimed pit floor. DMG's previous recommendation to construct erosion resistant <br />channels across the 3H:IV slopes, results in 375 feet of ditch, lined with 224 cy of riprap. The <br />upland diversions proposed in the adequacy response letter of 8/31/95, will result in 1500 feet of <br />ditch, 1160 feet of ditch to be vegetated and 340 feet of ditch to be lined with 410 cy of riprap. <br />The bond calculation, enclosed with this adequacy letter, assumed the least expensive option of 375 <br />feet of ditch and 224 cy of riprap. Please clarify which option DMG should calculate the bond <br />amount for. <br />The proposed upland diversions would be located inside the perimeter of the affected area. A <br />riprap lined ditch, 3 foot deep with 2H:1V side slopes, has a cross section dimension of l6 feet. <br />Please see attached sketch titled, "Riprap Lined Ditch". If permanent diversion ditches are <br />installed, the extent of mining will limited an additional 16 feet to allow adequate clearance for cut <br />and fill method of backfilling the highwall. <br />