2011-10-24_HYDROLOGY - C1981035 (3)

Home Browse Search

INSPECTION REPORT Site: National King Coal Mine, GCC Energy , Hesperus, Colorado Inspection Date: 3rd Quarter Inspection, Sept 23, 2011 Don R. May, P.E., Project Engineer Ponds: Photograph 1 shows the west pond and photo 2 the east pond. Both ponds appear to operating properly. The inlets, outlets and embankments of both ponds are generally in good condition although the depth of both ponds should be checked and sediment removed to assure the design volume. The inlet of the west pond show some signs of continued erosion. Drainage Ditches: The rock lined "dirty" drainage ditch that carries water from the top of the waste pile is shown in photograph 3. Flow in an area on the left bank, looking downstream, approximately half way down the channel appears to be jumping the channel bank and eroding the adjacent hillside. This area is highlighted in the photograph. The channel should be modified to prevent overtopping in this area. Photograph 4 shows one of the inlet - outlet drainage areas in the upper yard. A drop inlet drainage grate covered with debris is highlighted in the photo. All pipe and drainage grate inlets should be checked and cleared of blockage. Care should be taken not to bury drainage grates or ditches with the new fill being placed in the yard area. Except where noted, all drainage features have been constructed and are operating as stated in the drainage plan submitted to the Division of Reclamation, Mining & Safety. Coal Waste Pile: In general the waste rock refuse pile is in good condition. The face of the pile appears stable and shows no signs of unwarranted erosion. This is shown in photo 5. In the last inspection waste material had been stockpiled on top of the pile. This material has been spread and the top appears in good condition as seen in photo 6. The slope and compaction of the placed material should be checked to assure they meet the design requirements. The drainage ditches on both sides appear in good condition except for the area discussed above and shown in photo 3. As reported previously, a significant amount of mine waste has been stockpiled in the upper yard, adjacent to the toe of the waste pile and where the coal storage pile used to be. It appears that this material will be used to extend the pile on the lower end. If this is the case, it is important that the design specifications for the placement of fill on the waste pile be followed. Refer to previous inspection report for further discussion. Except for the items mentioned above the fill on the waste pile has been constructed as specified in the design approved by the Division of Minerals and Geology.