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Most, if not all of the entrenching erosion on Collector Ditch M can be eliminated by preventing Lateral K from contributing water to Ditch M. Permission was requested from the DMG to remove Laterals I,J,and K during the late summer 1994 in an effort to control erosion on Ditch M. Permission was granted and construction was completed in the early Yall. Most of the runoff that formerly collected in Laterals I and J and was diverted to Lateral K is directed now to Lateral H and thence to Sedimentation Pond No.2. Removal oY the three laterals has significant impact on the Northwest Sediment Trap. The Trap will be involved with lesser quantities of surface runoff, and the contribution of clastic debris to the Trap from Collector Ditch M should be minimized. Additionally, the developing vegetative cover will attenuate surface erosion on the reclaimed area. With these factors in mind it seems reasonable to request permission Yrom DMG to inYill the sediment trapping area (that area below the 1.7 Foot inside diameter culvert that directs runoff waters from the reclaim area, beneath the access road, to the Explosive Storage Area Sedimentation Pond). After the infilling is complete, the structure will not impound any water, sediment in suspension will pass through the culvert and the north embankment will serve as a water control/diversion dike. The PROPOSED MODIFICATION drawing shows the approximated outline of the infill area on the plan map, and the level of infilling on each oY the embankment profiles, A through G. Infilling below the culvert during the winter is difficult to impossible and has the additional problem of incorporating ice and snow into the fill area. It is respectfully suggested that the conversion oY the Sediment Trap to a Water Control/Diversion Dike be accomplished in the spring of 1995, at a time when ground conditions will allow proper inYill operations with minimum surface damage to the reclaimed area. The culvert from the Northwest Sediment Trap to the inflow channel of the Explosive Storage Area Sedimentation Pond was design-sized at 18 inches, inside diameter, to adequately function for a calculated peak runoff of 9.3 cfs from a 100 year 24 hour precipitation event (Meadows No.l Mine Permit C-81-029, page 301, Appendix 2.05.3-10A). A 20 inch, inside diameter, culvert is in place and is more than adequate to pass the 100 year 24 hour peak flow of 5.16 cPs. SEDCAD+ Version 3 calculations, attached hereto, set forth runoff and peak flow volumes as per the current acreage measurements and vegetative development on that portion oY the Pit Reclaim Area that drains into this culvert.