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;' Richard D. Lamm Governor DEPARTMENT OF NATURAL RESOURCES "' " - s99 D. Monte Pascoe. Executive Director MINED LAND RECLAMATION DIVISION DAVID C. SHEL70N Director ~_ January 11, 1983 T0: Sandy Emrich FROM: Jerry Zimpfer/,~_ 1 RE: Technical Rev_iJsion to Permit I6-16 for Compliance with Water Quality Control Division, Revised November 30, 1982 I have completed my review of the technical revision to the Mine No. 3 permit. This revision changes certain aspects of the existing sediment control plan. My review has examined only the revisions included in this submittal, and has not considered the complete sediment control plan for the Mine No. 3 permit area. The following items identified in my review should be addressed by the applicant. Sediment Pond E 1j The submittal does not include a detailed snap and cross-section for the pond. This makes the plan difficult to review. The applicant should submit a map and cross-section of the pond showing design details. 2j Pond E is sized for a 35 acre watershed. My estimates indicate that greater than 50 acres of watershed drain to the pond. Pond sizing may not have included undisturbed areas draining to the pond or there may be additional surface diversions not shown on the maps. The applicant should either verify the 35 acre watershed area or revise their calculations to reflect the total area draining to the pond. 3) Pond E includes 0.48 acre -f t. of sediment storage. This storage componed was sized for 0.02 acre -f t, of storage per acre of disturbance. The sediment yield from reclaimed or undisturbed areas was not taken into account. The applicant should submit calculations indicating that the proposed sediment storage volume is sufficient for the sediment yield from the entire drainage area to the pond. 4) The applicant should indicate the cleanout frequency anticipated to 423 Centennial Building, 7373 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567