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Schwartzwalder Mine -Hydrologic Evaluation of Mine Closure and Reclamation 115 7.3 Sump Water Quality Water in the alluvium was intercepted by four collector trenches and sumps (Figure 10) that operated from 1990 to June 2002 (Section 4.2.3). During operations, water in the sumps contained moderate levels of TDS (300 - 935 mg/L) and few dissolved metals, with the exception of zinc, molybdenum, and uranium (Table 30). Sulfate, bicarbonate, calcium, sodium, and magnesium were the primary components of TDS in the sump water. Compared to samples from alluvial monitoring wells, the sump water generally contained 50 - 100% more dissolved solids, and higher concentrations of molybdenum, uranium, and zinc. Water quality in the sumps was nearly indistinguishable from water quality in well MW6, which had a slightly lower TDS and comparable concentrations of molybdenum, uranium, and zinc. Water quality in the sumps has generally improved since the sumps were shut down. TDS concentrations in Sump decreased from 935 mg/L in May 2003 to 417 in March 2005, while zinc concentrations declined from 0.232 mg/L to 0.045 mg/L over the same period. Uranium in water samples collected from the sumps since 1998 are shown in Table 31. The trends of uranium concentrations in the sumps is somewhat similar to the trends in Ralston Creek (Section 6.5.2), although the sumps are much less affected by seasonality. After the sumps were turned off in June 2002, uranium concentrations in Sump 1 increased due to a "first flush" of water through the alluvium. Concentrations in the sumps have generally declined since that initial flush (Figure 39). Average annual uranium concentrations in Sump 1 declined from 1.38 mg/L in 2003 to 0.89 mg/L in 2004 and 0.74 mg/L in 2007. The sumps are slated for removal, in accordance with the Mine Reclamation Plan. 7.4 Seep Water Quality Although numerous seeps exist below mine property along the access road where groundwater surfaces at the contact between the alluvium and underlying bedrock, long-term monitoring of these natural seeps has not been conducted. On mine property, seeps were somewhat limited while the sumps were in operation. Two historical seeps on mine property included the "Parking Lot Seep" and the "Sump 3 Seep". Water quality was monitored in the "Parking Lot Seep" from January 1998 to August 2001. Uranium concentrations were very consistent, and averaged 0.026 mg/L with minor variation throughout the monitoring period (Table 31). The seep was removed in 2001 when the emergency storage ponds were reclaimed and the area was regraded. The "Sump 3 Seep" existed near MW9 and Sump 3. Here, water emanated from a low point in the fill during the wet season. Since the sumps were shut down, water levels have risen in the alluvium and fill. The seep is still in existence, and was sampled for uranium on August 8, 2007. The sample, labeled as SchwartSpring, had a dissolved uranium concentration of 0.301 mg/L, which is about half the concentration measured at Sump 1 in fall (September) 2007 (0.675 mg/L) and 60% higher than the concentration measured in Sump 3 in spring (May) 2007 (0.185 mg/L). These results indicate that the water emanating from the Sump 3 Seep is not identical to the water in the nearby sump, although it may be related to the French Drain system previously installed at Sump 3. 4109B.071116 Whetstone Associates