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Whetstone <br />ASSOC/ateS Technical Memorandum <br />The Operator's water treatment consultants have estimated that start-up and first year's <br />operating expenses for a water treatment system capable of treating the mine pool water <br />would be significantly more expensive than treating groundwater that reports to Sump 1. In <br />addition, although it is not clear that installing a submersible pump in the mine pool is <br />feasible, the estimated cost of drilling, setting a pump, installing buried piping, and operating <br />the submersible pump for the first year would be significant. <br />Treatment costs would increase if uranium concentrations increase due to oxidation of wall <br />rock in the underground mine. <br />25) On page 15-10 in the discussion of source removal, Operator states that the alluvium disposal <br />plan that was approved by the CDPHE Radiation Management Unit includes a provision to dispose <br />of contaminated alluvium in the underground workings of the Schwartzwalder Mine. This proposed <br />activity represents a change to the approved Reclamation Plan. Therefore, operator cannot proceed <br />with this activity until it has been approved by the DRMS. Detailed plans must be provided to DRMS <br />with the amendment. Underground disposal of any material that may contain radionuclides or other <br />potentially acid- or toxic forming material must be preceded by geochemical testing to evaluate the <br />potential leaching behavior of the material. The locations of the samples collected for these tests <br />must be documented as to location (by GPS coordinate), physical description of the material, <br />quantity of material, plus photographs of the material sampled. The testing methodology must be <br />approved in advance by DRMS, and should consist of a standardized accelerated weathering test <br />such as EPA method 1312 or equivalent methodology similar to that employed for TR-10. <br />DRMS previously approved the disposal of water treatment sludge and concrete in the Minnesota <br />adit, via Technical Revision 910. The proposed source removal planned for summer 2010 which <br />was approved by the CDPHE Radiation Management Unit under Radioactive Materials License <br />(RML) number CO-369-03 has been postponed, but will be initiated no later than August 1, 2011. <br />The Operator intends to perform a comprehensive study for identification and characterization of <br />source term materials within the alluvial fill including, but not limited to, RML area #2 as described <br />in the RML decommissioning and license termination plan. This study will follow a targeted <br />strategy as follows: <br />1. Assess water monitoring data from the newly reinitiated stream water sampling stations <br />along Ralston Creek adjacent to the alluvial fill to identify any regions of alluvial fill that <br />may have greater influence on uranium loading to the creek. These areas may represent <br />locations of priority interest for depth profile soil sampling within the alluvial fill. <br />2. Examine the results of item #1 along with historical documents and previous gamma survey <br />data across the surface of the alluvial fill to select targeted locations for depth profile <br />sampling in areas expected to have the greatest potential for source term material that may <br />have the greatest impact on alluvial groundwater and surface water in the creek. <br />3. During the late summer or fall season when water tables are expected to be as low as <br />possible, use a backhoe to dig small trenches that provide access to the soil profile for in-situ <br />gamma measurements and soil sampling at incremental depths. Take photos and document <br />4109C.100731 17