2008-09-04_HYDROLOGY - M2007044 (2)

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Page 3 September 2, 2008 other with an annulus of approximately 6-inches and filled with washed gravel. The outside CMP is approximately 36-inches in diameter. The sump is being constructed in a stub-drift located at the bottom of the decline just opposite the drift dog-leg that trends to the west. The floor of the mine immediately down decline of the seepage and in the area of the sump drift had been deepened to a depth several feet below the bottom contact of the sandstone bed with mudstone. It is intended to backfill this low area to provide a high and dry running surface of the tunnel above the sump pumping level. In the sump area, the back and ribs have been bolted and shotcreted. However, seepage from the bolts and fractures underneath the shot-crete was prevalent, and appeared to be contributing water to the sump floor at an estimated total rate < 1 gpm (Photos 5 and 6). Drift Area Seepage in the west drift that extends from the bottom of the decline is common on most exposed faces of the back and ribs in the form of wet surfaces, thin films of free water, and dripping rivulets. Small pools of water on the floor were also common. Similar to other areas in the mine, flow of this diffuse nature is difficult to quantify, but it is reasonable to assume that the combined yield in this drift section was at least 1 to 2 gpm (Photos 7 through 9). As mentioned previously, this seepage may be due to storage of groundwater in the surrounding rocks during the time that the decline was flooded. Surface Reconnaissance Surface reconnaissance focused on observations in the vicinity of the ore-bearing sandstone (Morrison Formation, Salt Wash Member) outcrop/subcrop area downslope and north and south of the Whirlwind Mine portal. This stratigraphic horizon is of hydrologic importance in evaluating existing and future discharges of groundwater to the surface. Characterization of existing discharge from this unit, as well as inter-stratigraphic units located between the portal elevation (Morrison Formation, Brushy Basin Member) and the ore-bearing zone is expected to provide valuable baseline information downgradient and cross-gradient of the Whirlwind Mine and Packrat Mine within or in the vicinity of the mineralized strata. Reconnaissance was conducted from the Bonanza Mine, on the north flank of Lumsden Canyon, to the Rajah 49 Mine portals, approximately one-half mile northeast of the Whirlwind Mine. Figures 1 and 2 show key observation and sampling points identified during the reconnaissance. Reconnaissance was limited to the vicinity of the Salt Wash Member sandstones and associated workings, where previous roads and benches had been constructed and are now reclaimed. Areas above and below this stratigraphic horizon were visually scanned and physically traversed on the roads to the Dutchman Mine and Packrat Mine, and a southern traverse from the Rajah 49 Mine area south to County Road 5/10. DP Spring, located just south of Lumsden Creek and Lumsden Fault at an elevation of approximately 7,100 ft, was observed in upper section strata near the base of the Burro Canyon Sandstone. Surface water was observed in three locations along the Salt Wash Member traverse, including Lumsden Canyon (Creek), Packrat (PR) Spring, and in the drainage below the Packrat Mine dump. Sampling of Lumsden Creek and PR Spring is discussed in a subsequent section of this report. Lumsden Creek was observed as flowing from above its intersection with County Road 5/10 (Photo 10) to below the Dutchman Mine dump (Photo 11). The stream flows immediately adjacent to and partially through the dump materials. This is because the dump is situated on the north flank of the canyon and has encroached upon the creek's channel, partially from dump deposition practices and partially due to storm runoff and mass wasting (Photo 11). Weans090108.doc