Laserfiche WebLink
III Illlllllllllllll <br />999 <br />(~~ /,~~~ f I /, <br />I/IV/J~ Jii <br />/ " ~ ~~ 1 V l . /' <br />` V ~. I <br /> ENVIROCON, INC. <br />• J95 WEST IRONW000 DRIVE <br /> SOUTH SALT LAKE CITY, UTAH 84115 <br /> TELEPHONE' X8011 485-9565 <br /> FA% (8011485-1444 <br />EN»IROCON, INC. <br />August 9, 1994 <br />ENV # 1430.30014 <br />IVIrs. Kathy G. Welt, Environmental Supervisor <br />Mountain Coal Company <br />West Elk Mine <br />P.O. Box 591 <br />Somerset, Colorado 81434 <br />RE: FACTOR OF SAFETY SUMMATION FOR LONE PINE GULCH <br />PROJECT <br />• Dear Kathy: <br />The fOliv'.~illg IeLtcI SUa.:uil~SlZco the aiter5 Of UafCty" fOr tale proposed I..^..E <br />Pine Gulch Fan portal, subsoil stockpile and topsoil storage pile. The proposed Fan <br />bench will have a cudfill balance of approximately 31,500 cubic yards, of which <br />26,100 cubic yards will be used during reclamation. The total fan bench and sub soil <br />staging area is approximately 3.01 acres. The topsoil disturbance area is <br />approximately 0.47 acres. The following paragraphs describe the slope stability <br />analysis £or these piles. <br />A slope stability analysis was performed in profiles depicted on drawing LPG <br />-103F. The slope stability analysis utilized the PCSTABL5 program to determine the <br />factors of safety against failure. The factor of safety is the ratio of the forces resisting <br />the slope movement to the forces which cause the slope to fail. The resisting forces <br />are determined by the shear strength of the native soils to resist failure along a <br />specific surface. The forces which tend to cause failure include; but are not limited <br />to: (a) the angle of the slope; (b) the location of existing haul roads and drainage <br />ditches in relation to the slope; (c) pore pressure or water table acting on the failure <br />plane; and (d) the characteristics of the native soil and bedrock found in the slope. <br />A factor of safety of 1.0 implies that the slope is marginally stable for the cross- <br />section profiles, native clay/topsoil material strengths, groundwater, and the slope <br />• conditions. In designing the various piles and the fan bench, Envirocon has used a <br />A7l~.~_Compeny ~~ <br />