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Formation <br />General Description <br />Porosity <br />Transmissivity <br />Morrison Formation <br />Mudstone with fine <br />grained interbedded <br />sandstone. The <br />Morrison shales are <br />confining layers, <br />while the lower <br />Morrison sandstones <br />are aquifers. <br />0 -10% (Freeze and <br />Cherry, 1979) <br />Low in the upper <br />Morrison. Low to <br />medium in the lower <br />Morrison (Gloyn, <br />1995). <br />Junction Creek <br />Sandstone <br />Fine to coarse <br />grained eolian <br />sandstone <br />5 -30% (Freeze and <br />Cherry, 1979) <br />Above average <br />permeabilities and <br />porosities <br />Wanakah marl <br />Fine grained <br />sandstone mudstone <br />and marl <br />Very low to low <br />Very low to low <br />except in areas of <br />fracture and faults <br />(Gloyn, 1995) <br />Wanakah - Pony <br />Express Limestone <br />Laminated micritic <br />and algal limestone <br />Very low to low <br />Very low to low <br />(Gloyn, 1995) except <br />in areas of fracture <br />and faults. <br />Entrada Formation <br />Fine to coarse <br />sandstone <br />5 -30% (Freeze and <br />Cherry, 1979) <br />Very low to low <br />(Gloyn, 1995) <br />Dolores Formation <br />Shale and siltstone <br />with interbedded <br />sands and <br />conglomerates <br />0 -10% (Freeze and <br />Cherry, 1979) <br />Variable generally <br />low. <br />o Discharge from outcrop to stream channels. <br />In general, the underlying porous media would have the following relative hydrogeolgoic <br />properties based on the composition of the formations. <br />When examining the recharge potential for the site, it would appear to be extremely low as <br />the underlying geologic formations are generally low permeability layered material which <br />would inhibit recharge of water from the slopes to the underlying formations. In addition to <br />the low permeability material, onsite observations indicate that the alluvial/fluvial cover on <br />the hillsides is extremely thin and the hillsides are relatively steep. These two factors will <br />tend to reduce the time of concentration of any overland flow from precipitation or snow <br />melt events thus minimizing the amount of recharge that could enter the ground water <br />system. Additionally, the faulting in the area has caused offsets of geologic formations that <br />place units of differing permeability and porosity in contact with each other thus effectively <br />limiting the flow of potential recharge water from areas of high potential to lower potential. <br />Frequently, if geologic formations of differing permeability are in contact on slopes where <br />recharge is occurring, the near surface recharge is forced back to the surface and either <br />springs or enhanced vegetation can be found along these zones. Finally, this same faulting <br />has created small, isolated areas for potential recharge to infiltrate the bedrock in the local <br />