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-?0- PAr. Richard Atkinson May 14, 1981 • Page Six shown on Figures 3 and 4 of Exhibit 7, and calculations for the designs contained in Annexures A and B to Erhibit 7. 7. Two permanent diversions along Southern Boundary: The Adequacy Review stctes that the two permanent diversions olone the southern boundary should be removed as part of the reclamation and all pre-:pining drainage restored. 1"fie conctir that both of these ditches may be removed es part of fir•al reclamation. However, the removal should be after all of the mine fill area is fully restored, so as to minimize erosion to the mine fill area. 8. Peestablishment of Surface Drainaee: The Adequacy Review raised concerns about the reestablishment of surface drair.aae. The proposed post mining draimae pattern consists of drainaces along the face of the fills in berm ditches, terrace or contour ditches to the principal drainaces v:hicii are located cpproximately cs presently located. Draincge along the bergs and terrcces eras selected as a means of minimizing erosion on the slopes. Selection of this method of conveying flow to the principal drainages should clso match the pre-mining hydroloeic regime closely cs the same area is being dreined by a complete s; stem of c::annels. The A.dea•scy P.eviev+ clso rcised ccnc~.-~ cbcut severcl minor valleys dreining • to the north ba.;rdcry cf the mine ogee. In.t:.e Section 4 mining area a smell crew is not being re~nnected to its existing dreir.c_es, os this is in the final area which will be finished off somewhat lower than the present contour and hence canna- be reconnected to its original drainage pattern. Also the drainage must be directed to e sedimentation pond, end is thus directed into the Taylor Gulch tributary pond. 9. Convex Hillslooes: The Adequacy P.eview raised concern<. over the convexity and end the gradient of the lower hi Ilsides. V'ith the berm, terrace, and contour ditches draining the hillsides to the principcl drainaces erosion should be well controlled, end there should be no differences between the fills as laid out, and revised fills' that would flatten the lower slopes out and add more fill in the center of the area. Additiorolly, tha layout os drawn up,. by inspection, appears to approximate the pre-mining condition closer than a revised plan that v+ould add more fill in the center of the mining area. A copy of 29 sheets of computations made in connection with these responses is enclosed. We trust that these responses adequately address the points rcised in the Colorado Mined Lond Reclamation's Adequacy Review that relcte to our engineering work for Colowyo's Permit Application. •