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~. 5.0 CONCLUSIONS Groundwater flow in the Hayden Gulch area is from southwest to north- east. Principal aquifers are the coal seams of the lJilliams Fork and Iles Formations and the massive Twenty Mile and Trout Creek Sandstones. Eighteen springs and seeps were found in valley bottoms within 1 mile of the site; probably only four of these will be affected temporarily by the proposed mine. Only nine water wells were found within four miles of the site, although there are likely a number of additional unregistered wells in the area. None of these wells are expected to be affected by the proposed mine. Due to low transmissivity and storage coefficient values, iow volumes of pit inflow can be expected. Down-dip ground- water impacts appear to be negligible because of the limited amount and movement of subsurface water. The two deep sandstone formations (Twenty Mile and Trout Creek) have little chance of being affected by mining due to 300 feet of impermeable shale and marine deposits separating the aquifer and the coal seams. Chemical analyses revaled that the two coal zones are similar in quality; moderately alkaline, moderately high in total dissolved solids, and relatively high in calcium and sulfate. The coal aquifers were found to be relatively dry at the south end of the site. Mining backfilling and reclamation will create a larger recharge area than existed originally. It is likely that the four springs impacted will resume at premining flow rates and quality characteristics. The larger recharge area will probably not increase groundwater flow down- dip due to the geologic characteristics (low transmissivity) of the undisturbed adjacent formations. Overall, the impact caused by mining is not likely to significantly effect the groundwater resource based on the data collected and analyzed by VTN and Morrison-Knudsen. Both water quality and quantity will be continued to be monitored to assess mining impacts and deviations to the groundwater resource.