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Wallace H. Erickson <br />Division of Reclamation, Mining and Safety <br />Department of Natural Resources <br />December 16, 2013 <br />a worst -case probable maximum flood (PMF) storm event. The Initial Detailed Inspection <br />Report will further discuss the stability of the dam under the flood loading condition. <br />5) It states that the Operator has completed certain repairs including "installation of a <br />new liner material to replace the eroded liner ". (Report p.3) Have actions been taken by <br />the Operator or by DRMS to determine the viability of the entire liner underlying the LTF <br />as it impacts its ability to contain water? Note the testimony by the Operator in the 1990 <br />MLRB transcript that "the synthetic liner was designed for use during the operational <br />period of the mine, and not for an indeterminate period of time ". (Complaint p.3) Further <br />reclamation at the mine site should have been achieved 10 -15 years after mining had <br />ceased (or by 2012). (Complaint p.3, Lyle testimony) <br />Response to Paragraph 5: <br />A liner is situated on the north, downgradient side of the tailing embankment to manage <br />stormwater infiltration and runoff. An approximately 10 feet by 200 feet section of the liner in <br />this area is exposed on the surface to convey clean stormwater runoff from the embankment. In <br />April 2013, an approximately 15 feet section of this exposed liner was replaced and tied into the <br />adjacent covered liner on the downgradient side of the embankment. <br />BMRI maintains an extensive monitoring system, consisting of monitoring wells and <br />lysimeters, to ensure that the lined tailing facility and collection pond system are functioning <br />properly and remain protective of downgradient water resources. The current monitoring system <br />is summarized in Technical Revision 32, and is further described in BMRI's April 15, 2013 <br />submittal to DRMS. <br />6) Have repairs been conducted on the disturbed area that is 200 feet long by 50 feet <br />wide? (Report p. 4) <br />Response to Paragraph 6: <br />The referenced disturbance was associated with the replacement of a portion of the <br />stormwater conveyance liner on the north, downgradient side of the embankment as described in <br />the response to paragraph 5 above. That repair work was completed in April 2013. Final <br />reseeding will be completed in spring 2014. <br />7) There is a seep associated with the outlet of the drainage blanket for the tailing pond. <br />Routine maintenance and other actions are required to ensure its continued function. <br />