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INTEROFFICE MEMORANDUM <br />TO: MEMO TO FILE <br />FROM: JANET BINNS <br />SUBJECT: FOIDEL CREEK MINE, C1 <br />DATE: 9/9/2008 z 1 <br />" <br />CC: DAN HERNANDE7/, <br />On August 20, 2008 TCC provided a revision to the previously submitted designs for a mine water storage reservoir at <br />6MN at the Foidel Creek Mine, TR61. This change proposed to lower the elevation of the emergency spillway to <br />6714.9 feet. This will reduce the capacity of the impoundment to approximately 34.3 acre feet with a surface pool of <br />roughly 5.1 acres. The embankment and associated ditches will be constructed and maintained as the original design; <br />however, the spillway elevation reduction effectively reduces the volume of the pond. <br />These changes to the impoundment design were forwarded to Kent Gorham (DRMS) for his review, and The Colorado <br />Division of Water Resources for their comment. <br />September 2, 2008: Kent Gorham (DRMS) provided a memo to Janet Binns (DRMS) concurring with the proposed <br />changes to the impoundment design. <br />September 3, 2008: TCC provided DRMS with a copy of Colorado Division of Water Resources, Division VI, <br />Division Engineer's approval for a non jurisdictional dam for TCC's 6MN Mine Water Impoundment. TCC also <br />provided a copy of TCC's communication with MSHA regarding changes to the 6MN Impoundment design, and <br />MSHA's May 13, 2008 approval of the original impoundment design. <br />September 8, 2008: Dan Hernandez forwarded an e-mail from Mark Haynes, State Engineer's Office, reiterating that <br />approval of a non jurisdictional pond excludes that pond from being revised to a jurisdictional pond for a period of 10 <br />years. <br />September 9, 2008: DRMS sent an e-mail message to TCC requesting TCC provide a calculation of the Factor of <br />Safety, both static and seismic in accordance with Rule 4.05.9(8). These calculations were not submitted with the <br />revised pond design. <br />I went through the file back to the Division's Adequacy letter, dated August 30, 2007, and October 22, 2007, to assure <br />that all adequacy concerns had been addressed and resolved. <br />Items remaining included: <br />#15 (August 30, 2008 letter numbering), which was re-asked to the operator in the 9/9/08 e-mail. <br />#30 Resolved. Areas that this question pertained to, the water line corridor and Fish Creek crossing were reviewed <br />and approved in MR-228. <br />#37 This a is a duplicate of item #15. Once Item 15 is resolved, this will be as well. <br />#38 Since #15 & 37 were applicable, item #38 was no longer applicable. This item is eliminated. <br />#42 Discussion with Tom Kaldenbach (DRMS) finds that the revised design would have no more than a 10 ft. head <br />of water in the pond. This calculates to -4.3 psi of hydraulic head. This would be minimal and the Division is <br />not concerned about impacts to the groundwater with the current proposed design. This item is resolved.