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- MORRISON-KNUDSEN COMPANY, INC. <br />/~ Mr. Cass Legal <br />e October 21, 1981 <br />Page 2 <br />July 31, 1978, and was prepared by Chen anal Associates, Inc., of Denver, <br />Colorado. No borings were drilled in the vicinity of the slope selected <br />far analysis. However, borings were drilled for a,s~itlinq_pond embankment <br />southwest of the sloe analyzed. ~ ~ aad~it~"rc i <br />n_ ~~ vl~:'rise:ds.*for•.•t~alb~l=i:t~y;;~an ~ ~s'~s of the .~all~e, <br />Bathe°7aga,l;yses pf the~° ;o' Consideration was given <br />o reducing- these strength parameters. Doing so could not be justified, <br />particularly, since the above-referenced report notes the presence of sand- <br />stone outcrops at the same elevation as the base of the slope analyzed. <br />st c; ay;ex.tends to considerable depths below the toer:o~f. ~ •,• ~ The <br />it strength parameters previously used are believed to be sufficiently <br />conservative far the present purposes. or~..'t•~e° long_ter~mµ'cd,~a~ ~~ <br />''c`,p,l..;ma.fenial_ should. i,ncre~se_in shear strength as~.i'f; c;,n~ ~ b <br />I "•e ~~the load imposed by the spoi~h aba <br />w F~'~oj~[ogai,.c. _Co"~d i t iYOb~s~ <br />o ;.ei~ana.l:y~ses discussed and reported in the July, 198¢ : ra o'i~~ <br />~e<,dtb:at.ino- phreatic surface exists within th:e~ spo~i!:: This as- <br />sumption was based on statements by mine personnel that no seepage has been <br />observed from the spoil pile after a rainstorm. <br />For the more recent analyses, the same slope with the same sets of strength <br />parameters were used. T~Fae+o,p.u,rpose of these analyses wasiit <br />~q i.>rhe phreatic surface would have to: be to reduce the4 <br />• tiyb'out~ 15,5. `4The results of the analyses indicate that~al <br />',, ~9~to•,.;1,~;0; feet above the toe of the slope would be requ~ir <br />=''~o.r;,~;of. safety`~~to about 1.5:~ <br />The spoil pile is irregular in shape. At its northeast corner, it is <br />• mounded to a maximum elevation of about 7625 feet. The southwest half is <br />generally flat, benched, and about 50 to 75 feet lower. In the event of a <br /> <br />M133 <br />• ~ is l ilYf ~~i6v,~~i. i ~ i <br />