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Carol Pahlke December 23, 1980 Page 7 The emergency spillway for pond depth was designed for the 25-year AMC-II, precipitation event as indicated on Plate 1 of Exhibit 29, as amended. The spillway was sized for the peak inflow to the Pond, without regard for the attenuation that the Pond would provide. In the November 11, 1980 calculation set forth in Revised Exhibit 42 ("Effect of County Road on Spillway Operation, Pond F"), the same peak discharge is used. The purpose of the calculation was to determine if the backup behind the road embankment due to the 48-inch culvert would affect the operation of the spillway. In actuality, the reduced flow which would result due to the attenu- ation provided by the Pond would backup much less than 13.6 feet. This would result in a much greater level of freeboard and ensure no road overtopping. Revised Exhibits: Revisions to Exhibit 29 and Exhibit 42 were previously submitted to MLRD and OSM as part of the December 4, 1980 response of Kerr Coal to the MLRD November 6, 1980 Adequacy Review. Based on information submitted to date from Kerr Coal Company there is a major issue that still needs to be resolved. The Division is concerned about the revegetation and erosion prob- lems that may result when Pit #1 is reclaimed. We are concerned that excessive topsoil may be eroded from the site and impede revegetation due to high slopes, reduced infiltration due to soil dispersion, lowered permeability leading to possible drought conditions, and the possible for- mation of impermeable layers between the topsoil and spoil. There are many factors contributing to this problem. Pit $1 has slopes in excess of 308 which have a higher than normal potential for soil erosion. The spoil used as a subsoil is sodic and high in clay content as indicated by the revised overburden analysis. The problem is further compounded by the fact that only six inches of suitable topsoil will be replaced on this site.