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STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 C O L O RA D O <br />Denver, Colorado 80203 DIVISION o e <br />Phone: (303) 866-3567 MIN 6 RA L S <br />FAX: (303) 832106 G E O L O G Y <br /> 0.ECLANATION•M INING <br />SAiETY•SCIENCE <br />February 26, 2004 <br /> Bill Owens <br />Ron Thompson c°vemGr <br />Peak Project Management Russell George <br /> <br />34115 County Road 20.8 Executive Director <br /> <br />Trinidad CO 81082 Ronald W. Cattany <br />Division Director <br /> Natural Resource Trustee <br />RE: Excess Spoil Fill Inspections <br />2na <br />3rd and 4th Quarters 2003 <br />~ <br />Lorencito Canyon Mine, #C-96-084 <br />Mr. Thompson: <br />The Division of Minerals and Geology has completed review of the 2"d, 3ro, and 4th <br />quarters of 2003 excess spoil fill inspections for Fills 7, 8 and 9 at the Lorencito Canyon <br />Mine. Comments from review of the 4th quarter 2002 and 1gt quarter 2003 are repeated <br />below in italics for your review. <br />Under the heading Sediment Control for all three excess spoil fill inspection <br />reports, the text states `All surface runoff from the fill areas is directed to this <br />sediment control facility". P/ease identify by name each specific sediment control <br />facility. <br />2. Each report contains a heading titled "Drainage Systems (Underdrains)". While <br />the underdrain is an important feature of each fill, after the drain is covered, the <br />presence of seepage from the drain becomes the only significant observation <br />during the inspection. No specific reference is made under this heading <br />regarding other surface drainage on each fill. The Division recommends another <br />heading be included in each report for surface drainage on, and above (in the <br />case of valley fills), each fill, directed towards function and condition of terraces <br />and downdrains. Experience has shown that these two constructed features are <br />the most likely candidates for future problems due to surface runoff and <br />sedimentation. Proper drainage at ten-ace/downdrain intersections is critical to <br />prevention of erosion and damage to the body of the fill. Stability of the channel <br />lining in the Downdrains is also critical to stability of the body of the fill. <br />Review of the 2"d, 3rd, and 4th quarter inspections for Fill 7 and Fill 9 document no <br />activity as these fills were previously constructed. The 3ro and 4th quarter inspections <br />for Fill 8 document construction of the fill through revegetation on the upper 2 benches. <br />Downdrains were not riprapped as of the 4th quarter inspection and revegation of the <br />lower benches was also in-progress. Topsoil sampling results were included with the <br />Office of Office of Colorado <br />Mined Land Reclamation Active and Inactive Mines Geological Survey <br />