2010-04-05_HYDROLOGY - C1981041 (6)

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SNOWCAP COAL COMPANY NORTH AND SOUTH PORTALS IMPOUNDMENT YEARLY INSPECTION In accordance with Rule 4.05.9(14), all impoundments shall be inspected at least yearly to determine if the impoundment has been maintained as designed, and in accordance with the approved plan and the applicable regulations. This yearly inspection is for the impoundments located at the North and South Portals, Unit Train Loadout, North Decline and Refuse Disposal Areas. On March 23, 2010, 1 performed the required yearly inspections. I, J. E. Stover, have a wide variety of experience in the design and construction of earth fill embankments. Nothing was observed during the inspection that would indicate the ponds have a potential for failure. There was no appearance of erosion, instability, structural weakness or other hazardous conditions. There are no required monitoring procedures or instrumentation other than quarterly and yearly inspections. Unless noted below in the discussion of each pond, there are no aspects which might affect stability and there is no required maintenance. None of the pond/impoundments were discharging during the inspection. Ponds 1 and 2 are located at the Unit Train Loadout. They were dry to damp during the inspection. Volume III, Appendix 13-2, page UTL-5 indicates the combined ponds are designed to contain the 25-year 24 hour event and still have significant excess capacity. The ponds were certified by Larry M. Reschke, P.E., on June 1, 1995. Based on the certification statement and current measurements of the sediment poles, the sediment capacity of the ponds has not been affected since 1995. Therefore, the sediment ponds have significant excess capacity plus the following design capacity: Water Sediment Total Ponds 1 & 2 - A-F 1.99 0.46 2.45 Pond 6 collects run-off from CRDA-1. The pond was damp during the inspection. There are approximately 2.3-feet of sediment buildup in the pond. This figure is derived from the average length of the three sediment poles located in the pond minus the design depth. The percent of sediment buildup is 43% (2.3 deep divided by 5.4' maximum depth). Based on this sediment buildup and aerial topo maps, the pond has the following estimated capacity: Water Sediment Total Pond 6 - A-F 1.33 0.95 2.28 -1-