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MLRD LETTER OF MARCH 5, 1987 COMMENTS & RESPONSES MLRD COMMENT: APR l.j 1957 Area 41 Fvlltvr=i, ~.-.....: DECLAMATION DI`JISION We find that the plan proposed in the revision for Area 41 does not represent approximate original contour. The Area 41 plan includes significantly oversteepened slopes at the base of the spoils and a cross slope diversion ditch above the steep slope at the base of the spoils and a cross slope diversion ditch above the steep slope segment as a permanent structure. This plan does not comply with the provisions of Rule 4.14.2 which specify that "...final graded slopes shall not exceed in grade either the approximate pre-mining slopes or any lesser slopes approved by the Division" and "final graded slopes need not be uniform but shall approximate the general nature of the pre-mining topography identified in 2.10.3(1)(j)". Further, the plan depends upon structural controls which are not appropriate for the post-mining land use. Consideration needs to be given to reduced slope gradients as the appropriate means of stabilizing the area. The pre-mining topography map depicts an ephemeral tributary of the South Fork of Foidel Creek with a gradient of approximately 20% in the area in question. By contrast, the proposed plan would result in a slope gradient of over 40%, and no attempt would be made to restore an ephemeral channel which would approximate the general nature of the pre-mining topography. The proposed diversion ditch which would intercept surface drainage above the steep slope segment is not an appropriate substitute for a well designed, naturally appearing ephemeral drainage with a channel gradient of 20% or less. RESPONSE: As stated in the report prepared by Water Engineering and Technology, Inc., and further supported by legislative intent, the overall operation has achieved the AOC requirements. CYCC is of the opinion that AOC requirements apply to the entire mine area and not isolated areas within the mine area.