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STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />fAX: (303) 832-8106 <br />DATE: October 4, 2002 <br />TO: Tom Schreiner <br />PROM: Allen Sorenson ~~ <br />D I V i 5 1 0 N O F <br />MINERALS <br />GEOLOGY <br />RECLAMATION <br />MINING•SAFETY <br />Bill Owens <br />Governor <br />Greg E. Walther <br />Executive DIreC(Or <br />RE: Mining Setbacks to Assure Stability of Offsite Structures Coulson Ronalgd W. Cattany <br />r Actin Division Director <br />Excavating Company, Ins, Stroh Gravel Pit, Pile No. M-2002-078 <br />Mining at the Stroh Pit will encroach to within 200 feet of two critical structures that aze not owned by <br />Coulson Excavating. These structures are the Kaneb high-pressure liquid petroleum pipeline and the <br />Hillsboro Ditch. The permit application includes three basic components that address the stability of <br />these structures. These are: <br />1. Defined mining setbacks from the structures. <br />2. A copy of a letter dated January 30, 2001 from Kaneb Pipeline to Larimer County listing their <br />requirements for mining to within 50 feet of the pipeline. <br />3. Quantitative stability analyses of the anticipated mined pit slopes at setbacks of 50 feet as <br />measured from the toe of the slope. <br />The setback from the pipeline is 50 feet from the crest of the mine pit slope with a further requirement <br />to maintain the pit slope at 3H:1 V as mining approaches the pipeline easement. The terms of this <br />setback and sloping requirement originated with the Kaneb letter to Larimer County and the Applicant <br />has, through language provided in Exhibit S, incorporated the terms of the Kaneb letter as enforceable <br />conditions of the mined land reclamation permit. The following diagram illustrates the compliance <br />requirements protective of the pipeline. <br />