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aCOLORADO <br />Division of Reclamation, <br />Mining and Safety <br />Department of Natural Resources <br />Date: September 17, 2020 <br />To: Tabetha Lynch <br />CC: Jason Musick <br />From: Zach Trujillo <br />RE: Foidel Creek Mine, DRMS File No. C-1982-056 <br />Foidel Creek Mine MR20-317 Review Memo <br />Tabetha, <br />As requested I have reviewed Foidel Creek Mine's (Foidel) proposed suspension bridge for a 200-foot <br />section of the Overland Belt. The design consists of two steel towers, each sitting upon two 30 inch <br />caissons which will be constructed into bedrock. The overland belt will then be suspended by cable from <br />the towers with the cables anchored by large concrete blocks. The design of the suspended bridge, as <br />proposed, results in a 2.72 safety factor with a fully loaded conveyor. However, given the history and the <br />need for a suspension bridge, there is no discussion on how the proposed bridge will resist ground <br />movement such as slides. While the caissons will be constructed into bedrock, the anchor blocks will be <br />placed in the soil at a depth of 7 1/2 feet per the proposed design. In the event of a slide, the anchors could <br />shift or move with the ground leading to some of the tensile forces acting perpendicular to the length of <br />the bridge. This has the potential to negatively affect the stability of the suspension bridge. Please have <br />Foidel address how the proposed suspension bridge will resist potential ground movement and remain <br />stable. <br />This concludes my review of Foidel's MR20-317. If you have any questions, feel free to contact me. <br />Sincerely, <br />Zach Trujillo <br />Environmental Protection Specialist <br />(303) 866-3567 ext. 8164 <br />Zach.Trujillo@state.co.us <br />Foidel Creek Mine MR20-317 Memo September 17, 2020 <br />OF COlO <br />Few _ <br />h <br />1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us I <br />* Jared S. Polis, Governor I Dan Gibbs, Executive Director I Virginia Brannon, Director r t <br />