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water (USDW). Such aquifers are known to exist only well above the mining interval <br />and the nahcolitic oil shale overlying the mining interval. No water was encountered in a <br />well completed by AMSO within the Wasatch Formation, which underlies the mining <br />interval. <br />b) Maps and cross sections of Geologic Structure of Area <br />A north-south cross section showing identified oil-shale units beneath the AMSO site is <br />presented in Figure 5-6. The locations of the wells used to construct the cross section are <br />shown in Figure 3-2. <br />The R1 test interval is composed of illite oil shale, which characteristically exhibits low <br />permeabilities. Evaluation of groundwater yield to an AMSO well completed within the <br />RI suggests the unit yields water at a rate of less than 0.01 gpm_ The low yield prohibits <br />the collection of groundwater samples from the R1 test interval at the site. <br />The U oil shale unit is the nearest water-bearing unit to the R1 test interval within the <br />Green River Formation that is known to readily yield water to wells. At the AMSO site, <br />the U unit lies immediately above the dissolution surface, and approximately 200 feet of <br />oil shale of varying oil shale grades separates the R1 test interval from the U unit. The <br />oil shale strata separating the RI from the U zone contain unleached nahcolite occurring <br />as disseminated aggregates, nodules, and crystalline bedded units. <br />A geologic map showing structural features in the vicinity of the AMSO site is presented <br />in Figure 5-7. As shown, the AMSO site is located near the axis of the Black Sulphur <br />Creek Anticline which trends NW-SE, with beds dipping gently to the southeast (1°-10°). <br />Faults mapped by USGS are located approximately 0.5 miles to the southeast and east of <br />the site. During construction of the Test Pad, located east of the pad at which pilot <br />testing will be performed as shown in Figure 3.2, a small normal fault and associated <br />sandstone dike was mapped trending N 40° E and cutting across the southern end of the <br />Test Pad (Figure 5-8). The fault is downthrown on the southwest and appears to be the <br />northeastern bounding fault of a graben. Although the structure was not expected to <br />compromise the utility of the Test Pad, ANISO elected to move the pilot retort location to <br />beneath the TM Pad east of the Test Pad <br />13