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• All sedimentation ponds, impoundments and diversion ditches will be constructed before any disturbance of the undisturbed area to be drained. Wyoming Fuel Company is not aware of any past or present underground mining activity in the planned pit areas, so subsidence effects should be negligible. All sedimentation ponds, impoundments and diversion ditches as planned (see Figure 2) are located as near as possible to the disturbed areas and are out of perennial streams. Effluent limitations contained in 4.05.2 will be maintained. All sedimentation ponds are designed such that there will not be outflow through the emergency spillway resulting from a 10-year, 24-hour precipitation event. The foundations of all sedimentation ponds and impoundments will be cleared of vegetation and topsoil and scarified before construction. The ponds and impoundments will be constructed of selected compactable mine spoil and subsoil from the pond areas • applied in lifts and compacted during construction. The embank- ments and surrounding disturbed areas will be stabilized with a vegetative cover to minimize erosion. All sedimentation ponds, impoundments and diversion ditches are designed under the direct sugervision of Thomas R. Young, Registered Engineer No. 3831, State of Colorado, and will be inspected for structural weaknesses, erosion and other hazardous conditions during construction and quarterly upon completion. Certification of the constructed ponds and impoundments will be forwarded to MLRB as soon as possible. All sedimentation ponds and temporary impoundments will remain in place until the disturbed area is revegetated and drainage entering the structures meets effluent standards. Ponds #1 and #2 were approved as permanent impoundments in 1991. • - 3 6- Revised 11/29/94