Laserfiche WebLink
<br />Golder Associates Inc. <br />200 Union Boulevartl. Suite 500 <br />Inkewootl. CO USA 80228 <br />Telepnone(303J980~05a0 <br />Faa(303J985-2080 <br />March 3, 1997 <br />Mountain Coal Company -West Elk Mine <br />1 Mile East of Somerse[ on <br />Highway 133 <br />Somerset, Colorado 81434 <br />FAG~~o^lder <br />L1~C~~ <br />Our Ref: 963-2178 <br />r' <br />RE: SYLVESTER GULCH FACILITIES AREA SLOPE STABILITY <br />TECHNICAL iVIEMOR?u~iDUM <br />Dear Eric: <br />Golder Associates Inc. (Golder) is pleased to submit this technical memorandum to <br />Mountain Coal Company (MCC) for the clarification of the slope stability analyses <br />performed on the Sylvester Gulch Facilities Area (SGFA). <br />1.0 BACKGROUND <br />Golder was retained by MCC to provide slope stability analyses for the Sylvester Gulch <br />Facilities Permit Revision Submittal (PR07). Subsequent review by Colorado Division of <br />Minerals and Geology (CDMG) raised questions concerning the adequacy of the analyses <br />to represent current and future stability. This memorandum details the methodology and <br />justification of the material properties used for the slope stability analyses performed on <br />the project and provides adiscussion/evaluation of long-term stability within the SGFA. <br />Posi construction as well as post reclamation slope stability analyses were performed on <br />critical sections along the main access road, substation site, and the shaft site. Slope <br />stability was evaluated for slope failures that may have significan[ impact on the <br />constructed facilities, as opposed to shallow soil creep, which will be addressed by MCC <br />as a maintenance issue. The factors of safety reported are estimates due to the fact that the <br />specific potential shear plane, water table level, and material properties are not known at <br />this time. During the early stages of this project, Golder reviewed and field verified the <br />mapped landslides. The alignment and design of the roads and facilities took under <br />consideration the existing mapped landslide areas. In addition, a geotechnical investiga[ion <br />has been proposed which will obtain soil strength parameters from laboratory testing that <br />can be used to better define the slope stability variables in specific areas. <br />G=•CES IN AUSTRALIA, C~'.AGA, GE.<'.1AN`/. HUNG~i<V, iTALV, 5`NEGEN. UNITED'n'INGDOM. UNITED STATEi <br />