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Although the hydrologic properties of unsaturated bedrock strata of the area are unknown, . <br />the tightly cemented sandstones and shales underlying the area likely inhibit the vertical <br />movement of infiltrating surface w;3ter. Field observations of exposed bedrock suggest <br />that secondary porosity (due to weathering and fracturing) may significantly increase the <br />hydrologic properties of near-surface bedr oclc. Nevertheless, the infiltration and <br />permeability rates of unsaturated bedrock are probably much less than those of soils. The <br />hydrologic properties of saturated t~edrock are addressed in the "Aquifer Characteristics" <br />portion of Tab 7. <br />Soil water availability is a primary factor affecting the establishment of plant growth on <br />reclaimed areas. Studies of strip-mine spoils in the northern Great Plains have shown <br />that until vegetation and soil structure are established on topsoiled spoils, infiltration <br />rates are usually less than those of nearby undisturbed soils (Schafer et. al., 1979). <br />Root systems and soil structure (and, therefore, infiltration rates) resembling natural <br />areas are established on topsoiled spoils within three to six years. However, a study of <br />reclaimed spoils at the nearby Seneca II Mine conducted within three years of reclamation <br />showed that spoils were being recharged at an annual rate of two to six inches of water <br />per unit surface area, a rate which is substantially larger than natural recharge rates • <br />for the area (Williams and Hammond, 1988). <br />The permeability rates of reclaimed topsoil and spoil materials should be higher than in <br />undisturbed areas due to the disruption of natural bedding or layering, and a loss of <br />pre-mine compaction. Spoils at the nearby Seneca II Mine resaturate quite rapidlyi <br />preliminary results of U.S. Geological Survey spoils aquifer tests indicate that <br />transmissivity rates are approximately 50000 ftZ/day. Recharge of spoils is from the <br />vertical infiltration of precipitation and Che lateral movement of ground water from <br />adjacent areas. Spoils recharge will be enhanced by the decrease in transpiration <br />associated with the initial reduction in vegetative cover that occurs in reclaimed areas. <br />Additional discussion of spoils water hydrology and chemistry can be found in the <br />"Probable Hydrologic Consequences" portion of this permit. application (Tab 17). <br />Discharge. Discharge is the process by which ground water is removed from the saturated <br />zone across the water table or piezometric surface. Discharge mechanisms include <br />evapotranspiration, flowing or pumping wells, springs and seeps, leakage through confining • <br />layers that are not completely impermeable, and ground water movement into discharge areas <br />(e.q., streams, swamps, lakes, springs, and seeps). <br />24 <br />