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STATE OF COLORADO <br /> MINED LAND RECLAMATION DIVISION of Coto <br /> Department of Natural Resources <br /> 1313 Sherman St, Room 215 `F o <br /> Denver. CO 80203 * " <br /> 303 866-3567 .8, <br /> FAX 303 832-8106 <br /> Roy Romer, <br /> Governor <br /> Fred R.Banta, <br /> Division Director <br /> December 13, 1990 <br /> Mr. Brad Gosche <br /> National King Coal Inc. <br /> P.O. Box 2905 <br /> Durango, CO 81302 <br /> Re: Technical Review for Drainage Control <br /> Dear Mr. Gosche: <br /> As per our telephone discussion on December 12, 1990 the following is a list <br /> of items that should be considered in the technical revision for the <br /> reconstruction of the ponds and any revision concerning drainage from the <br /> topsoil pile. <br /> 1 . Add a dewateri ng device to each pond or commit to pumping the ponds after <br /> a precipitation event. The dewatering/pumping should be accomplished <br /> 48 hours after any storm that brings the water above the level allowing <br /> the pond to subsequently contain a 10 year/24 hour event. <br /> Rule 4.05.6(3) (c). <br /> 2. Construct a separate emergency spillway that can safely pass a <br /> 25 year/24 hour event for each pond. Pending rule change 4.05.6(3)(d) . <br /> 3. Reslope the embankments for each pond in order that they comply with the <br /> requirements of 4.05 .6(8)(d)-(g) . <br /> 4. Increase the west pond capacity to allow for greater sediment storage <br /> volume to preclude frequent sediment removal 4.05 .6(3)(b) . <br /> 5. Install markers to indicate maximum sediment levels and maximum water <br /> levels for periodic cleaning and dewatering. <br /> 6. Add to the permit the sediment pond calculations for the east pond. This <br /> information should also take into account the amount of water that is <br /> intended to be diverted from the east drainage ditch during high runoff <br /> periods. <br /> 7. Include in the permit the drainage control measures for the topsoil <br /> pile. This area, however, could be proposed as a small area exemption <br /> with its own sediment control system using any combination of berms, <br /> sediment traps, or silt fences. <br />