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/I^-Ig77_300 <br />fi?? 0 <br />cotter <br />--a - I Z, <br />Via Email and U.S. Mail <br />July 7, 2010 """ <br />Colorado Department of Public Health and Environment <br />- Water Quality Control Division / WQCD-B2-CAS <br />Compliance Assurance Section <br />Attention: Michael Harris <br />4300 Cherry Creek Drive South <br />Denver, CO 80246-1530 <br />Subject: Technical Memorandum:. Proposed 100-gpm water treatment system and request <br />for alternate discharge outfall location, Schwartzwalder Mine. <br />References: 1) CDPS Discharge Permit No. CO-0001244; <br />2) June 15, 2010 meeting among Cotter, DRMS, WQCD; and <br />3) the Radiation Management Unit of the CDPHE WQCD Notice of <br />Violation/Cease and Desist Order, Number: I0-100601-1 <br />Dear Mr. Harris: <br />Per the request of the Water Quality Control Division ("WQCD") at the above referenced <br />meeting, please find the attached Technical Memorandum, providing planning details for a new <br />nominal 100-gpm ion exchange water treatment plant, a groundwater pumping/piping delivery <br />system, and a new outfall location to discharge treated groundwater to Ralston Creek. The <br />WQCD indicated that agency authorization to initiate this mitigation measure by July 31, 2010 <br />could be granted through an amendment to the Notice of Violation/Cease and Desist Order, <br />Number: 10-100601-1 ("Order") issued on June 1, 2010. <br />Cotter Corporation (N.S.L.) ("Cotter") plans to initiate operation of this water treatment system <br />by July 31, 2010. The objective is to mitigate surface water quality impacts to Ralston Creek <br />from groundwater percolating through alluvium and fill materials adjacent to the Schwartzwalder <br />Mine. The WQCD has further indicated that Cotter should submit a new CDPS permit <br />application. Because agency review and issuance of a new pen-nit is expected to take longer than <br />can be achieved by July 31, 2010, Cotter is requesting an amendment to the Order for interim <br />approval. <br />In addition to providing a means for active removal of uranium from all water reporting to Sump <br />Number One, the system is designed with the capacity to pump/treat water reporting to other <br />sumps or monitoring wells as necessary. Stream monitoring data will at specified time intervals <br />be evaluated to identify any additional groundwater pumping/treatment or other mitigation <br />measures that may be necessary to achieve acceptable water quality in Ralston Creek.