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~,_ <br />,:ter s,'~~: <br />~: ;~~,; . <br />Lincoln DeVore,lnc. <br />Geotechnicel Conwltants <br />1441 Motor St. <br />Grand Junction, CO 87505 <br />LJ <br /> <br />Balaz & associates <br />203 Sttr.set Circle <br />Palisace. CU 81526 <br />TEL: (970) 242-8968 <br />FAX: (970) 242.1581 <br />Fabruary 5, 1991 <br />Re: Vew Coal Msste Pile Project, Sanborn Creek Pline, <br />Scmerset, CO <br />Dear "!r. Balaz: <br />as requested, Lincoln DeVore is completing slope stability analy- <br />sis of t!re .^.ew access roads associated with the above referenced <br />pro±ect. In particular, cut and .fill sections. nears the Somerset <br />town cemetery and accessing the new coal waste pile are being <br />analyzed. In addition, the sediment pond at the base of the new <br />coal waste pile is to be addressed. .4 full report is being <br />prepared whir: it will :pore fully address the cut and fill stabilit}• <br />of the ac=ess in maul 1•oad. In addition, the proposed Sediment <br />Fend and the loe areA of the new coal waste pile will more folly <br />,ilscneced. Tlie following discussion is intended to be a summary <br />of Olll' fltlllings. <br />geo!ngy, as r:,rrrentlp understocd through limited road cuts and <br />as~rimirg t},e rrce of nati~•e materials. when possible. It has been <br />t•ecummr:uled '.hat t}.e road cuts in the relati•~ely low to medium, <br />drn~tty callut•;um soil he limited to approximately 10 to 12 feet <br />in heigi,l., with a maximum alnpe of 1:1•.ri. Tn addit.inn, fills on <br />rho co]].n•i um coilc should be limited to 40 fiat in height meac- <br />,it•rd from I}re fill crest to the toe, with a maximum slope Wit' <br />access acrd Haul. Roads;. Slope stabilit}• analysis have <br />been made r.n the naturally occurring slopes along the proposed <br />and t}iP e~isLinq acr.ess and }caul coals. Several geometries Cor <br />c•ut. acrd till were considered, considering the esistinq slope <br />!:l n. .\LI fill areas will reyni.re benching lnr.o the oat i•~e <br />al,:~l,ec .an,i, i,ol~eful.l;• irrterceptinq CF,e weathered bedl•cck materi- <br />als of the Anwie t~femher• of the MPSA Verde Format, nn. if it is <br />riesirPd to inr_rease the sloe angles to 1:1, the .fills will <br />Prol,ahlc reynire mechanicAll}• reinforced soil. Pill, possibl}• <br />being bnLLr•,+s~t•~1 and fac•rri with bcnrl•ters. This mechanical rein- <br />Cor•cina m.r~ ,~til izc either gec te~ttle fabrics or geogrid t}-pe <br />materials. IL is nntlclpated that naturall}• occurring large <br />gobble sized And boul.drr sized frazments oP sandstone will be <br />,rtSlized as surface facing and ttre ¢eote`ctile ot• ,leu,~a•i,l will rtut <br />be e.cposed .o ull.rx,~io let raJialion. <br />