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• nearest upgradient mining activity in the initial cuts of the A East pit. Mining in this area has to date had no <br />obvious effect on flows at this site. Flow from this spring is not expected to be impacted during post-mine <br />conditions. This spring exists near the southem limits of the Third White Sandstone outcrop and has been <br />thought to emanate from the Third White Sandstone. A travertine deposit has been noted to exist on the <br />surface at the site of the Fox Den Spring. This deposit may indicate that water quality from this spring was <br />significantly different in the past for some period, or that the source of this spring is from a deeper aquifer <br />containing more highly mineralized water. Sulfate and TDS concentrations measured at the Fox Den <br />spring are similar to levels documented in Third White Sandstone wells GC-2 and GP-9. <br />A deeper source for the Fox Den spring would require that a permeable zone exists to transmit the water <br />to the land surface. Though no obvious geologic structural features have been identified in the immediate <br />vicinity of the Fox Den Spring, some subtle indications are present. A similar travertine deposit has been <br />noted to exist at springs to the east in Flume Gulch (Spring 99-2 and Spring 99-3). The alignment of this <br />spring and the Fox Den Spring roughly parallels a norfhwesUsoutheast trending regional fault system, the <br />Cedar Mountain fault system, north of the project area. This is the dominant geologic feature in the area. <br />The Big Bottom Syncline may have smaller displacements or slips associated with it that could <br />conceivably transmit water. This type of feature could account for flows at the Fox Den Spring. The <br />• IiUrologic units at Trapper have numerous layers of very fine-grained material which would be expected to <br />have sealed any significant vertical fracture zones or displacements. However, a small displacement on <br />the order of tens of feet may have occurred without the extensive sealing or smearing of the fracture zone <br />associated with a larger fault. <br />The springs in Flume Gulch (Spring 99-2 and 99-3) are near the southern limits of saturation in the Third <br />White Sandstone aquifer and have also been thought to be discharges from this groundwater system. <br />TDS and sulfate concentrations measured at these features occur at lower levels than those documented <br />at Third White Sandstone wells GC-2 and GP-9. Spring 99-2 flows from a vertical pipe at an old <br />homestead locatlon. Details regarding the installation of the pipe are unknown, however, field <br />measurements have shown the pipe extends down roughly 180 feet from the surface. The H seam is <br />known to lie about 30 feet deep at this location. The structural model for the site indicates the pipe at <br />Spring 99-2 extends nearly to the M seam. Based upon this information it is possible the flow from Spring <br />99-2 stems from waters derived from the KLM interval. An exploration drill hole was established roughty <br />40 feet west of Spring 99-2. This hole (99-AE23) was drilled to a total depth of 60 feet and was probably <br />initiated near the base of the Third White Sandstone. During drilling, the flow from spring 99-2 was <br />observed to stop as flow from the exploration drill hole commenced, suggesting the shallow exploration <br />borehole was providing an alternative flow path for the water normally discharged from the spring. Once <br />• the exploration hole was sealed, flow from the spring was reestablished. This may indicate that water <br />from Spring 99-2 is derived from a shallow source. <br />4-238a <br />Revision: T~ By <br />Approv~ET 4 v cuJ <br />