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Mayo and Associates, LC <br />.~ <br />I <br />I • <br />• <br />A 128-foot deep monitoring well.(1-O1S) in the floor of Mine 2 had a shut-in pressure of <br />60 psi. The pressure in the well indicated that the potentiometric surface of the water <br />encountered was 98 feet below the LOA Seam in the Storrs Member and was 138 feet <br />above the mine workings. Water in monitoring well 1-01 S had a t4C age of 18,500 yeazs <br />and contained no 3H. Differences in poientiometric levels and groundwater ages between <br />roof drips and the Storrs Member indicate that they are from groundwater systems that do <br />not have hydraulic communication with each other. The potentiometric surface of roof <br />drip waters is approximately the elevation of the sandstone channels. <br />3.5.2 Fault-Related Inflow <br />In Mazch 1999 mining activities in the southern portion of Mine 2 began to intersect a set <br />of north- to northeast-trending normal faults of relatively small displacement that <br />produced large inflows (Hydrologic Consultants, Inc., 2002). Initial discharges have <br />been as high as 6,500 gpm, although dischazges of about 1,000 gpm aze more common. <br />The discharges of individual fault intersections only decreased 30 to 50 percent during <br />the following three-year period. The numerous north- to northeast trending normal faults <br />aze par[ of the structural transition zone between two major graben forming fault zones; <br />the northern portion of the north-trending Joes Valley Fault zone; marked by the <br />Gooseberry Creek Fault, which is located west of Mine 2, and the north-trending Pleasant <br />Valley Fault zone, which is located east of Mine 2 (Figure 10). Only a few of the <br />transitional faults aze shown in the figure. South of the Mine 2 the Joes Valley Fault zone <br />has formed the Joes Valley Graben and north of Mine 2 the Pleasant Valley Fault zone <br />has formed the Pleasant Valley Graben. <br />Evaluation of Potential Groundwater Inflows 47 <br />Associated with E Seam Mining, <br />West Elk Mine, Somerset, Colorado <br />February 24, 2004 <br />