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Ground Water <br />• The Schwartzwalder Mine site can be separated into two (2) major, but not disparate, <br />groundwater flow regimes. These two (2) flow regimes consist of the shallow alluvial system of <br />the Ralston Creek valley and the deep, or semi regional system most closely associated with the <br />underground mine workings. The shallow alluvial groundwater system is the area that could be <br />potentially impacted by licensed facility activities. Alluvial sand and gravels underlay most of <br />the site surface facilities on the valley floor at varying depths of six to twenty (6-20) feet, with a <br />layer of loose fill from three to fifteen (3-15) feet deep overlaying the alluvium in many areas. <br />At this time the alluvium and fill are believed to lie on competent, unfractured amphibolites <br />basement material that slopes at a consistent, gradual grade to the southeast. Groundwater flow <br />through the shallow alluvium is primarily influenced by gaining and losing reach areas along the <br />course of Ralston Creek, although several historical natural springs with uranium concentrations <br />as high as 2 mg/1- are known to exist and commit a secondary influence at the Sump #1 and the <br />old Sump #2 location; localized groundwater studies, that included test bores of the foundation <br />areas, were performed during the construction of the Ore Crusher-Sorter facility and the <br />wastewater treatment facility. <br />Commencing in 1983 four (4) shallow monitoring wells was installed with the specific purpose <br />of monitoring groundwater characteristics on a long term basis. In the early 1990s, the number <br />of wells was later increased to nine along the length of the valley floor. <br />The original shallow sumps and catch basins installed to control the natural spring flows and <br />• surface runoff below the Ore Sorter and at the east end of the property were deepened to <br />basement. Uranium concentrations in Ralston creek below the site property line, though <br />consistently below the COPS discharge permit limits, declined further after the deepening of the <br />sump system. <br />According to a sump pumping records there is a clear correlation between pump rates of the <br />sumps and precipitation. This may account for the higher concentrations in Sump 1 and 2 during <br />the dryer months of the year. <br />The majority of the wells are sampled on at least a quarterly basis for dissolved uranium and <br />basic water quality parameters, while the sumps are currently sampled on a quarterly basis for <br />dissolved uranium and basic water quality parameters. Nine (9) monitoring wells and two (2) <br />sumps in the valley floor continued to be monitored in 2009 on a routine basis, with two (2) of <br />the wells typically dry. A new well, MW 12, was added in late 2008 for DRMS purposes. <br />Historic and 2009 concentrations for uranium are shown in the following figures. Sump 2 and <br />Sump 3 were not sampled in 2008 and 2009. <br />• <br />25