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<br />2ORICH - ERKER ENGINEERING, INC. <br />Page 3 <br />and the San Rafael Group, particularly the Sumrerville formation and the <br />Estrada sandstone. <br />Faulting offset is very evident in the study area. The proposed <br />open pit mine is located on the flank of a gently dipping anticline that <br />has both flanks cut by a series of subparallel faults; the overall effect <br />being the down faulting of the hY>rrison formation in the area of the mine, <br />thus, hydrogeologically isolating this block. <br />The area of the proposed pit mine is mantled by a veneer, up to <br />60 feet thick, of loose clayey sandy soil wntaining many boulders, pre- <br />dcRninantly of sandstone from the Aalcota sandstone and Burro Canyon for- <br />oration which form the steep slopes above the project area. <br />There is an existing well on the flat-lying terrain just to the <br />west of the current underground operation. This well has a total depth of <br />about 70 feet and a static water level of approximately 30 feet. This <br />well was pumped to determine its yield capabilities. A yield of approxi- <br />mately 1 gpm was sustained for a period of less than 5 minutes indicating <br />that the airount of water available from the area which could be affected <br />by the proposed mining operation is negligible. <br />The Dakota sandstone and the Burro Canyon formation are pre- <br />dominantly fine to coarse grained quartzitic sandstones, shales, and <br />muddtones largely in the form of massive, irregular and often lenticular <br />beds. These two geologic units have no effect on the groundwater in the <br />area of the proposed pit mine, as they are situated topographically above <br />and away from the proposed pit area. <br />