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. and infiltration rate. The subsurface strata in these areas consist predominately oftightly cemented sandstones and shales which act as barriers inhibiting vertical percolation. However, field observation of exposed outcrops and aquifer analysis data indicate that secondary porosity (weathered and fractured bedrock strata) play a significant role in allowing vertically infiltrating ground water to infiltrate through the unsaturated to the saturated zone. Quantification of the transmissivity and permeability associated with secondary porosity is difficult because ofthe lack of reliable aquiferanalysistechniquestodeterminesecondaryporosityinlowyieldingaquifers. The entire study area is impacted by irrigation which is a primary source of infiltrating water. Infiltration as a result of precipitation is a component of recharge in the Nucla area, but the majority of infiltration comes from irrigation. The large majority of the soils in the mining area have a slow to medium runoff potential. The second area of concern is the reclaimed areas. The strata at the New Horizon 1 & 2 mining areas are quite similar. The lithologic logs indicate that the spoils material will generally be composed of more than 50 percentfragments of blasted sandstone with lesser amounts of shale, bentonite and gypsum. Sections 2.05.3 and 2.05.4 describe the details of the mining and • reclamation methods. Using the described mining and reclamation techniques the approximate recharge capacity and permeability of the spoils material will be increased due to greater porosity and hydrologic conductivities due to increased void volumes. The resaturation rate ofthe spoils will be quite rapid because of fhe irrigation occurring in the area. Infiltration resulting from precipitation is only a very minor (2" per year) component, but does comprise a measurable percentage of the infiltration. Discharge Ground water is discharged through streams, evapotranspiration, wells, springs and seeps, and by subsurface outflow to contiguous aquifers to the southwest. Discharge rates from overburden, Dakota coal and the underburden can be calculated using Darcy's law. Calculations of ground water flow (inflow) from the overburden, Dakota coal and underburden indicate thatthe aquifers are discharging 77,058 ft lday, 663 ft'/day, and 4,133 ft3/day, respectively through the defined cross sections. Discharge from the Dakota coal and the underburden is relatively small compared to the overburden. There may be some discharge from f, J (REVISED 6/28/01) 2.04.7-9