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July 30, 2010 12 of 24 <br />mine pool is in hydraulic communication with the creek, yet insists that the mine pool must be <br />drawn down because of their probabilistic assessment that there is high risk that this will occur in <br />the future. The Division denies the validity of any risk-based assessments from Cotter, but <br />promotes their own risk-based arguments without supporting or scientific analysis. <br />DRMS and Cotter agree that there is no direct evidence that water from the mine pool is reaching <br />Ralston Creek. Denver Water has recently provided data showing that water quality at the water <br />supply intake to the Moffat Water Treatment Plant remains well below the 0.03 mg/1 drinking <br />water standard. There is clearly no imminent health threat to the public from the mine pool and <br />consequently, there is no need to rush into mine pool treatment before the effectiveness of treating <br />groundwater in the alluvial fill can be assessed. In addition, there are potential negative <br />consequences to mine water quality by drawing down the mine pool, as Cotter has discussed <br />repeatedly. <br />A scientifically valid, technically sound, risk assessment of quantifiable impacts to potential <br />receptors should prevail. <br />FEASIBILITY OF MINE PUMPING <br />The 8rh bullet point in Mr. David Bird's rebuttal testimony (before the MLRB on July 12, 2010) <br />indicates DRMS denies that dewatering poses substantial physical feasibility challenges in <br />installing a pump, pipe, and other equipment into the mine. DRMS states that "setting a pump at <br />500 ft below the Steve Level would not be exceedingly difficult". <br />DRMS claims the pump "can be lowered inside a casing string" but fails to explain how the casing <br />string can be lowered into the shaft without encountering and timbers, protruding edges, horizontal <br />bracing, and other potential obstructions (Figure 6). My professional experience in both running <br />casing in open holes and setting pumps in cased holes are that any obstruction can often prevent <br />the advancement of casing or pumps. Pumps have been known to "hang up" on something as <br />small as a welded bead, and casing will not advance. <br />DRMS states that the pump can be hung inside a casing string using centralizers, but fails to <br />explain how the casing string is centralized and anchored across the void spaces. Moreover, the <br />ability to seal the open voids around in the annular space and around the casing string (where it <br />passes through large mine voids) to meet state requirements for well sealing would not be <br />addressed. <br />Similarly, while DRMS cites numerous cases of drilling programs intercepting targets at depth, it <br />is not clear that any of those mines utilized the shrinkage stoping practices and timbering <br />employed at the Schwartzwalder Mine. It is not apparent that any of those drilling targets <br />contained significant open voids above the target or piping, wires, shoots, rails, and other <br />problems in drilling into the target (Figure 7, Figure 8). In the angled holes described by DRMS, <br />it would be impractical or impossible to set a submersible pump.