2012-06-22_REVISION - M1977300 - Laserfiche WebLink

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