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M _ ? ???- 068 <br />I WATER RESOURCE CONSULTAItiiT? <br />? Oct. 4, 2010 <br />Dustin Czapla <br />Colorado Div. of Reclamation, Mining and Safety <br />101 S. 3`d Street, Room 301 <br />Grand Junction, CO 81501 <br />LLC <br />CST ©0 2010 <br />Division of I?eraametron, <br />Minhig end Sad*ty <br />RECEIVED <br />RE: Loesch Pit, M-1981-068, Garfield County, CO. <br />,Technical Revision TR-003 - Pit wall liner- <br />Operator: Grant Bros. Const. Ltd. <br />Dustin, <br />'`-OCT 0 5 2010 <br />GRAND JUNG; I K;iv rlCLD OFFICE <br />DIVIC10I4 OF <br />RECLAvA 1&! MINING & SAFETY <br />As requested and discussed, this report provides justification for a Technical Revision to the <br />above noted mining permit. The scope of this Technical Revision addresses a liner that has <br />been placed on portions of the pit walls to help manage groundwater seepage during <br />operation of the pit. The original reclamation plan approved in 1981 did not anticipate use of a <br />wall liner for groundwater control, thus prompting the reason for this Technical Revision. <br />The attached Figure 1 overlays the mining plan onto the most current aerial photograph, taken <br />in 2009 by the NRCS. Mining to date has been concentrated in Phases I-IV. Phase V, VI and <br />P have not been opened to mining as of this date. <br />The remainder of this Technical Revision discusses the source of groundwater, how it has <br />been historically managed, groundwater management during the operational history of the pit, <br />and the incorporation of the pit wall liner into the reclamation plan. <br />SOURCE OF GROUNDWATER <br />Groundwater seepage into the pit is largely a factor of irrigation practices. The Last Chance <br />Ditch runs mostly parallel with 1-70 on the south side of the interstate south of the pit. It is <br />decreed for 57.17 cfs absolute, and per State Engineer diversion records', frequently runs <br />water year around. Seepage from the ditch, as well as seepage from return <br />' http://cdss.state.co.us, Last Chance Ditch, Structure Summary Report <br />244 Hutton Ave., Rifle, CO 81650 PH / Fax (970) 625-5433 pcunier@wrc-Ilc.com