Laserfiche WebLink
Carter <br />Technical Memorandum <br />Purpose <br />This Technical Memorandum presents information as requested by the Colorado Water Quality <br />Control Division ("WQCD") to evaluate water treatment at the Schwartzwalder Mine. It also <br />sets for a request by Cotter Corporation (N.S.L.) ("Cotter") to discharge the treated water to <br />Ralston Creek at a new outfall location. The WQCD has indicated that authorization to initiate <br />this mitigation measure by July 31, 2010 could be granted through an amendment to the Notice <br />of Violation/Cease and Desist Order, Number: I0-100601-1 ("Order") issued on June 1, 2010. <br />In accordance with paragraph 28.a of the Order, Cotter has initiated procurement and installation <br />of the necessary equipment and infrastructure to begin active treatment of groundwater <br />percolating through the alluvium and fill adjacent to the Schwartzwalder Mine by July 31, 2010. <br />An application for renewal of discharge Permit number CO-0001244 ("Permit') was received by <br />the WQCD on October 15, 2009. Cotter was notified in a letter from the WQCD dated April 8, <br />2010 that the Permit renewal review process was incomplete and that the Permit remains in <br />effect under an Administrative Extension. On June 29, 2010, the WQCD indicated that Cotter <br />should submit a new CDPS permit application including the information presented in this <br />document and other pertinent information. Because agency review and issuance of a new permit <br />is unlikely to be complete by July 31, 2010, Cotter is requesting an amendment to the Order for <br />interim approval. <br />Objective and Approach <br />The objective of the water treatment system detailed in this Technical Memorandum is to <br />actively remove uranium from alluvial fill groundwater in order meet applicable water quality <br />standards in Ralston Creek. Water treatment will focus on all water reporting to Sump Number <br />One. Cotter is requesting a change in the current water treatment discharge outfall location <br />(outfall 001) to a new location along the creek near Sump Number One (see Attachment 1). The <br />rationale for the proposed new discharge location is to maximize the beneficial impacts of <br />releasing treated water to the creek by preventing potential recirculation of treated water through <br />the alluvial fill. <br />The groundwater pumping/piping design for Sump Number One also includes provisions to <br />allow simultaneous pumping and treatment of water reporting to other sumps or monitoring <br />wells as necessary (see Attachment 1). Once treatment of Sump Number One has been initiated, <br />the water quality in Ralston Creek at sampling locations above, below and adjacent to the <br />alluvial fill will be closely monitored to evaluate relative locations and magnitudes of beneficial <br />effects. This information will be used to determine if supplemental mitigation measures are <br />required. <br />4