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r <br />Beginning in May 2008, uranium levels in Ralston Creek began to escalate to levels far in excess <br />of the water quality standards for Ralston Creek. Although conditions have recently improved with the <br />installation the Ralston Creek bypass structure, and the installation of Sump 10 and improvement of <br />Sumps 5 and 8, the efforts by Cotter to date indicate that long -term remediation and monitoring efforts <br />will be required to sustain a successful remediation of the Schwartzwalder Mine. Because of the <br />proximity of its drinking water system to the Schwartzwalder Mine, Denver Water has a significant <br />interest in any remediation plan which Cotter may implement at the Schwartzwalder Mine. <br />For your consideration, below are Denver Water's comments as well as the attached written <br />comments prepared by Denver Water's consultant, Arcadis Consultants, Inc. /Malcolm Pirnie, on various <br />aspects of Amendment 4. Based on these comments, and the attached comments provided by Arcadis <br />Consultants, Inc. /Malcolm Pirnie, Denver Water requests modifications to Amendment 4 and/or in the <br />alternative, objects pursuant to Hard Rock/Metal Minding Rule 1.4.9(1) to approval of Amendment 4 <br />without the modifications requested herein. <br />Denver Water commends Cotter for its efforts to isolate Ralston Creek, as wells as the Division <br />of Reclamation Mining and Safety ( "DRMS "), the Water Quality Control Division, Environmental <br />Protection Agency, and the Army Corps of Engineers for their efforts in coordinating the isolation of the <br />creek. Denver Water agrees that the isolation of Ralston Creek is necessary to prevent upgradient <br />groundwater and surface water from becoming impacted as it flows past the mine site, and to dewater the <br />alluvial fill so that other remedial measures, such as extraction of source term materials within the alluvial <br />fill, can be performed. Denver Water also commends Cotter for recognizing the need to remediate the <br />south waste rock pile. Cotter's plan in Section 4.2 of Amendment 4 to characterize and monitor the south <br />waste rock pile is a necessary first step. However, additional work may be required to fully remediate the <br />south waste rock pile. In addition, Denver Water believes Cotter has taken a serious step toward putting <br />together a remediation program for the Schwartzwalder Mine, although additional benchmarks, timelines, <br />and analysis must be incorporated into Amendment 4 in order to ensure that it is successfully <br />implemented and executed. <br />In terms of timeframe, Amendment 4 lays out separate timeframes for the south waste rock pile, <br />alluvial fill material, and treatment of the mine pool. However, Amendment 4 fails to integrate these time <br />frames; a step that is necessary in order to plan for an effective and timely remediation of the mine site. <br />Prior to approval of Amendment 4, Cotter should prepare and submit for comment and consideration an <br />integrated timeline for the implementation of Amendment 4, which incorporates benchmarks as discussed <br />below. An integrated time line would allow Cotter to plan, conduct and complete certain activities while <br />studying and preparing for other activities. For example, while Cotter begins to implement mine <br />dewatering, an activity which Denver Water believes is necessary, Cotter should at the same time perform <br />in situ treatment bench tests on mine pool water and implement a tracer program to identify leaking <br />unidentified core holes and faults and other fractures in and around the mine site. By developing an <br />integrated timeline, Cotter can better plan and coordinate the activities which must be performed at the <br />mine site so as to avoid delay in dewatering the mine pool. <br />Page 2 of 3 <br />Denver Water Comments /Schwartzwalder Mine Permit - Amendment 4 <br />M -1977 -300 <br />