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<br />. <br /> <br />N <br />N <br />o <br />W <br /> <br />at points along the t/hite River where the aquifers are in contact <br />with aaluvia. Water is discharged from springs along Evacuation <br />Creek, along the White River, or in a few places along the several <br />ephemeral streams in the area. Other quantities of ground water <br />are discharged to the west, in the direction of the water-level <br />contours, outside of the region of oil shale tracts U-a and U-b. <br />The ground water storage is presently in a steady state--discharge <br />equals recharge. <br /> <br />The principal aquifer in the region of tracts U-a and U-b is <br />known as the "bird's nest," which is the upper part of the Para- <br />chute Creek Member of the.Gr~en River Formation. This aquifer out- <br />crops at the surface at some locations in tFacts U-a and U-b. <br />Solution cavities are foroned from the dissolution of nahcolite <br />nodules in the marls tone and birds build nests in the cavities-- <br />hence~ the name. <br /> <br />. <br /> <br />Four test wells were drilled between Dececher of 1974 and <br />December of 1976. Flow rates varied from 0 to 700 gpm, with an <br />average of nearly 30 gpm. The aquifer is dry in the southwest <br />~ortion of oil shale Tract U-a but has an artesian head of 250 <br />feet in the more water-rich northwestern .part of Tract U-b. Water <br />level contours are closely spaced to the west in Tract U-b but are <br />more widely spaced in Tract U-a, since rock trans2issivity is con- <br />siderably higher there. It is estimated that nearly 80,000 AF of <br />~ater is stored in the bird's nest aquifer. <br /> <br />Water quality, in terms of TDS content, in the Green River <br />Formation (which includes the bird's nest aquifer) is consistently <br />petter than in the adjacent aquifers--that is, the Uinta Formation <br />above the Green River formation and the Wasatch formation below <br />the Green River Formation. Dissolved solid levels were lowest in <br />the Book Cliff area south of the oil shale tracts. In general, <br />water quality ranges from a high level of 4,030 ~g/liter of TDS <br />in the northeast portion of the oil shale tracts to a low of 1,760 <br />mg/liter in the southwest portion. Hardness also varies northeast <br />to southwest from 1,000 mg/liter to 69 mg/liter. A northwest to <br />southeast diagonal line bisecting the boundary line between tracts <br />U-a and U-b defines the lower average TDS level (2,540 mg/liter) in <br />the eastern zone (Tract U-b). Water is a sodi~sulfate-bicarbonate <br />type in both oil shale tracts. ~~st test wells produced a high <br />quantity of H2S gas in the water. Thus, the high levels of sulfate3 <br /> <br />8. About 60 to 90 percent of all of the flow in Evacuation Creek <br />is from surface runoff. Consequently, flow is extremely variable; <br />in 1976 the flow rate varied from 0.01 to 88 cubic feet per second. <br /> <br />. <br /> <br />D-16 <br />