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West Elk Mine . The pond is located on the natural bench above the valley floor at an approximate elevation of 6,290 feet. Normal surface runoff has been kept from entering Freshwater Pond-1 (FW-1) by providing a ditch upstream of the pond to intercept and carry the Probable Maximum Precipitation (PMP) assumption "B" storm flow to MB-1. This ditch keeps all nuisance flows from entering and combining with the raw water stored in the fresh water pond. A spillway section has been designed to pass many overland flows that may overtop this ditch and enter the pond. Spillway Designs Spillways have been sized using the broad crested weir equation, Q = CLF15. A coefficient "C", of 2.67 was assumed, as this is the low end of the practical range, Spillways aze constructed of riprap or gabions. The design head for each spillway has been limited to 2.50 ft. FW-1 Pond has a service spillway to assure that small inadvertent flows entering the ponds are passed without relying on the emergency spillway. The individual plan sets in Exhibit 43, Exhibit 47, and Exhibit 66 includes all pertinent hydrologic and spillway data. Stability Proeram Description The stability analysis for the dams was performed using a slope stability computer program (SLOPE II) developed by Geo Slope Programming, Ltd., Regina, Saskatchewan. The Ordinary • (Fellenius) Method and the Simplified Bishop Methods were used to compute stability factors of safety for each embankment's maximum cross-section. Both methodologies use the method of slices and utilize the limit equilibrium theory to solve the factor of safety. The principal difference between the two methods is the treatment of interslice forces. The Ordinary Method assumes that interslice forces can be ignored, while the Simplified Bishop Method assumes that the interslice forces act horizontally. Memck and Company's results indicated that the Ordinary Method yielded lower factors of safety in all cases. Consequently, for all subsequent trials on the given dam, only the Ordinary Method was used. The computer program determines the factor of safety for slip circles of varying radii about specified points but does not automatically converge on the minimum factor of safety. In order to minimize cost, a coazse grid was initially established. The grid was then successively refined to converge on the minimum factor of safety. In most cases three to five interactions were required. Stability analysis for SG-1 was performed using a slope stability computer program entitled XSTABL5.105. The program utilizes Bishops and/or Janbus method for circulaz or non-circular failure. Various soil states were investigated to determine the most critical condition for each embankment. The unconsolidated undrained condition, the consolidated undrained condition, and the consolidated drained condition were considered for all embankments. . In the case of MB-I and FW-I, for the clay material embankment, the consolidated 1.05-31 Revised June 2005 PR/0