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STATE OF COLORADO <br />DIVISION OF RECUIMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Raom 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />FAX: (303) 832.8106 <br />May 5, 2007 <br />Mr. Mark Heifner v <br />Southwestern Ecological Services <br />37 East Colorado Avenue <br />Denver, Colorado 80210-3105 <br />RE: M-1986-015 Pueblo Ease Amendment IZIM Adequacy Review <br />Dear Mr. Heifner <br />COLORADO <br />DIVISION OF <br />RECLAMATION <br />MINING <br />- &- <br />SAFETY <br />Bill Ritter, )r. <br />Governor <br />Hartis D. Sherman <br />Executive Director <br />Ronald W. Cattany <br />Division Director <br />NaNral Resource Trustee <br />The Division has reviewed your amendment application for the Pueblo East Pit (M-1986- <br />O15).The Amendment proposes to expand the affected acres by approximately 70 acres. The <br />amendment also proposes miming plan changes to Phase I. The slurry wall installation at <br />the end of Phase I has been deleted from the plan. Phase I is now being proposed to be <br />backfilled. The Division has the following comments: <br />I) Exhibits "A","E" &"C" Adequate <br />II) Exhibit "D" Mining plan <br />A) Under this exhibit, the operator is considering two options to dewater the pit. A <br />ground water barrier wall, such as a slurry wall, installed around all or part of <br />the area to be mined, that prevents or greatly reduces the flow of ground water into <br />the area during mining. The amendment refers to either a "slurry wall" or a "driven <br />sheet piling steel wall". No design is provided for the sheet piling or the slurry <br />wall. If the intention is to place the sheet piling in lieu of the slurry wall, <br />please provide a detailed PE. Certified design for the structure. All slurry walls <br />or any kind of barrier walls have to have an approval from the Colorado State <br />Engineer's Office prior to construction. <br />s) On page 4 you stated that "stream strengthening shall be installed along the <br />river bank south of Phase 2 at all locations where it is expected that erosion may <br />occur. Prior to engaging in such activity, approval if needed has to be obtained <br />from the Army Corps. You have also committed not to mine or affect areas with in 300 <br />feet of the river along the southern side of the pit until the stream bank <br />stabilization is completed. <br />C) you also stated that" a temporary overflow berm will be constructed along the <br />southern edge of the affected area. The berm might require FEMA, approval prior to <br />construction", Depending on the height of the berm, it might also require the <br />approval of the Colorado State Engineer. Please provide the detailed design of this <br />berm to DRMS, in addition to other agencies that could have jurisdictional <br />authority. DRMS main concern is that we have adequate bond to cover the removal. <br />D) It is the understanding of the Division, that the entire Phase I mining area will <br />be a series of settling ponds to be filled with wash fines & overburden from Phase <br />II, to an elevation between one half to three feet above ground water table and <br />reclaimed as Riparian forest/wild life habitat. Phase II is being proposed to be <br />reclaimed as WAT):',$~ STORGAE. <br />Office of Office of <br />Mined Land Reclamation Denver • Crand Junction Durango Active and Inactive Mines <br />