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<br />. <br /> <br />l\) <br />l\) <br />o <br />N <br /> <br />thickness ranges from 0 to 140 feet with saturated deposits up to <br />100 feet thick. Wells in alluvium can yield as much as 2,000 gpm <br />but only for brief durations (Coffin, 1971; U.S. Bureau of Land <br />Mgmt., 1976?). <br /> <br />Water quality from alluvial-sources varies from fresh to very <br />saline water. Salinity ranges from 250 mg/liter in the upper aquifers <br />to 25,000 mg/liter in lower aquifers near the mouths'of the various <br />streams (Coffin, 1971). Betause of high TDS levels, water from the <br />Piceance Creek Basin alluvia does not meet the 1962 U.S. Public Health <br />Service standards for drinking water (Weeks, 1974). <br /> <br />. <br /> <br />In summary, ground water supplies appear to be adequate for <br />roughly a 170,000 to 200,000 barrel per day oil shale operation <br />(3 barrels of water per barrel of oil) without mining the reserves <br />in Piceance Creek Basin. It should be noted, however, that the <br />distribution of water resources in the basin is not uniform and, <br />though the overall recharge rate may allow oil shale development of <br />this size, certain locales may require surface waters to supplement <br />their operations. There is concern, also, that ~hile withdrawal <br />rates may be lower than annual recharge, rock permeability and <br />hydrOlogic surface connections may cause problems by spreading cones <br />of drawdown (resulting in increased pumping costs) and by dramati- <br />cally reducing stream flows, since about 80 percent of stream flow <br />waters are derived from ground water resourCES in the Piceanc~ <br />Basin. <br /> <br />A significant portion of stream flow in the basin is derived <br />from deep aquifers of the Parachute Creek Member, so there is a <br />relatively close connectivity between upper and lower aquifers <br />(Coffin, 1971; Br~~ et al., 1977). This connectivity could very <br />well be increased by the removal of the Mahogany Zone through oil <br />shale mining. ~lining disturbance of aquifers will result in increased <br />TDS levels (Weeks, 1976), so it is possible that increased connec- <br />tivity would raise the levels of TDS in streams of the Piceance <br />Creek Basin. Existing levels of ground water quality will present <br />some processing cost problems, but properly positioned wells should <br />avoid undue proble05. <br /> <br />Most of the ground water recharge for the lower White River in <br />the UintE Basin (Fig. D.l) derives from precipitation on the Roan <br />Plateau. Minor amounts of water enter the aquifers along outcrops <br />1n Evacuation Creek, along the upper reaches of the various ephemeral <br />streams that drain the vicinity of oil shale tracts U-a and U-b,7 or <br /> <br />. <br /> <br />6. The source for most of the material to follow is VTN, Colorado, <br />Inc., 1977. <br /> <br />7. See Fig~re C.l in Appendix C for locations of oil shale tracts <br />U-a and U-b. <br /> <br />D-15 <br />