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Sectlon 780.21 (c) Continued. addition, maximum projected dewatering rates were used. Therefore, this simulation represents the worst case projection of water level decline in the adjacent area. Recharge Capacity. The baseline rate of recharge of the overburden aquifer in the mine plan area was estimated in Section 779.15 as 50,000 gallons per day per square mile. As explained in Section 316.51, the proposed method of mining will result in greater postmining permeability and recharge capacity in the mine plan area. However, since the actual rate of recharge depends on the water available to the aquifer from infiltration, projected post- mining infiltration rates, and the size of the recharge area, are the controlling factors in projecting the postreiuing rate of ground water recharge. Based on rainfall simulation studies by Lusby and Toy (1976), and • Gilley, et. al. (1977) at several mine sites in the Powder River and Great Plains coal fields, the infiltration, rates of undisturbed and newly reclaimed saturated soils were compared. Consistently, infiltration rates for wet soils in inches per hour were found to be 25 to 46 percent lower on reclaimed sites than on undisturbed sites. These results were obtained from high-intensity rainfall rates of over 2 inches per hour fen 45 to 60 minutes. Based on extrapolated data from these tests, 18 to 45 percent of high- intensity rainfall may be expected to infiltrate through saturated reclaimed topsoil. The recharge area of the overburden aquifer, shown on the Eckman Park Overburden Aquifer Piezometric Surface (Map 12), is currently a narrow subcrop where the aquifer is exposed beneath the topsoil. In the undisturbed condition, confining layers of shale overlying the overburden aquifer at depth prevent recharge by downward perco- lation. However, mining in Eckman Park and Energy Mine No. 1 • will result in an expansion of the postmining recharge area so 780-181