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Wallace H. Erickson <br />Division of Reclamation, Mining and Safety <br />Department of Natural Resources <br />December 16, 2013 <br />(Report p.4) Do we know if the recommended maintenance including sediment cleanout <br />and stabilization of the slope has been accomplished? <br />Response to Paragraph 7: <br />As part of the tailing impoundment underdrain system, three pipes run beneath the tailing <br />impoundment and into a lined channel where the captured water is conveyed to the collection <br />pond. The "seep" area identified in the DRMS Report refers to the location where those pipes <br />emerge from the toe of the impoundment and discharge to the lined channel. In April 2013, <br />BMRI completed routine maintenance at this location, which included sediment removal and <br />filling of small erosion channels on the embankment slope immediately above the pipeline <br />outlets. BMRI regularly inspects this outlet area to ensure there are no impediments to flow. <br />The Initial Detailed Inspection Report will further describe appropriate maintenance measures <br />for the outlet system. <br />8) Do we know if a properly designed debris screen was installed to protect the inlet for <br />the drop structure? (Report p.4) <br />Response to Paragraph 8: <br />The Initial Detailed Inspection Report will further evaluate whether a debris screen <br />should be installed on the inlet to the drop structure. As part of its stormwater system <br />inspections at the San Luis Project, BMRI regularly inspects this inlet area to ensure that there <br />are no obstructions to flow. <br />9) In reference to the June 2103 report of Mark Perry, there are several areas of interest. <br />Mr. Perry's attached June 3, 2013 letter to you notes "we have not assigned an overall <br />safe storage level, as the dam is an Exempt Structure per SEO Rules and Regulations ". <br />Further, he states in his report that "the SEO does not have expertise or experience <br />specific to tailings dams. Our recommendations and observations are provided based <br />upon Dam Safety experience with dams and associated facilities designed to impound <br />water" (Report p. 4) A key consideration is that in 2011 and 2012 the LTF was not only <br />used as a water storage facility, but annually over 150 acfl of untreated waters were <br />transferred to it. (Complaint, p.2) referring to Operator's records). Accordingly, Mr. <br />Perry's review of the LTF as a water storage facility would be relevant. Further, his <br />report states: Upstream Slope - "during normal operations the facility's water surface is <br />several hundred (horz.) feet away from the crest, the only potential for slope erosion <br />would be from a large flood event" (Report p.1) Further, in the Spillway section, he states <br />"It is not clear to us how the ditch and adjacent tailings embankment would perform in <br />6 <br />