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' ~~~ a <br />8~ <br />h ~~ ~ ROCKY MOUNTAIN GEOTECHNICAL~ INC. <br />Achieving Harmony with Earth <br />October 15, 1982 <br />Mr. William Tate <br />tti'estern Associated Coal <br />410 17th Street <br />Denver, CO 80202 <br />Re: Stability Analysis <br />Blue Ribbon t9ine Access Road <br />Dear Ftr. Tate; <br />This letter will serve as an addendum to our letter report of Flay <br />26, 1582, concerning the access road. At that tine, the results <br />of an analysis concerning a single cross-section on the access <br />read was reported. The purpose of this letter is to elaborate on <br />ana put in proper perspective the results of that analysis. <br />As mentioned above, the analysis concerned a single cross-section <br />and is not necessarily representative of stability conditions <br />along the full length of the access road. In our opinion, it <br />would be entirely appropriate at some point in time to better <br />define the nature of existing stability conditions along the full <br />lengtn or roar. upon completion of such a more thorough study, <br />specific recommendations pertaining to required slope treatment <br />for the access road cuts could be made. <br />With regard to the results of the initial analysis of May 26, it <br />should be pointed out that both residual strength conditions and <br />peak strength conditions were analyzed. Results, utilizing <br />residual strength conditions, pertair.primarily to areas which <br />have already exhibited movEment and which should obviously be <br />given consideration for some form of treatment in the future. <br />For those areas which have not exhibited any form of instability <br />or excessive mo~•ement in the past, the use of peak strength <br />criteria WOUld bE felt to be IDGrE appropriate. Therefore, <br />pending the results of an.y additional, more detailed analyses ir. <br />the access road area, w•e would rECOrnmend the use of the 10.5-foot <br />thictness or colluvial soil cover above the bedrocY. as a basis <br />for identifying areas of potential instability li.e. factor of <br />sarety less than 1.5). <br />Shculd you have any questions pertaining to this additional <br />information, please do not hesitate to contact Rocky Mountain <br />Geotechnical. <br />Sincerely, <br />ROCKY F' UNTAIF; G ECHNICAL <br />r.e L. y .E. KLM/sam <br />The Railroad Sca'.~on • 555 ekes Peak Avenue. Sw~e 107 • Colorado Springs. Colorado 80903 • (303i 634-1999 <br />