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� J9r. Ken Pntett <br /> October 27, 20f,4 <br /> � <br /> The results of our slope stability analysis, as sho�vn by Ihe lon'est safety factors for each condition. are pre,ented <br /> j in Uie following table: <br /> Table 2 <br /> � Slopc Stabilih� Anal}sis Resul[s <br /> Dlinimum Safet�� f��ctors* <br /> I <br /> � Conditions An:dczcd South Slonc \urlh Slopc <br /> � (I3-[3'Secliun) (:\-:�' Scction) <br /> Before cons[ruction I.i3 I.52 <br /> (Seismic PS = 1.03) Seismic FS= 1.0-I) <br /> ' Post-cunstruction,pond cmpty ���� ���'� <br /> Seismic FS = 1.17 (Scismic FS= 1.6�) <br /> I Pos[-wnstruction,stcady-sta[e seepage,pond at � �3 __ <br /> s ilhvav cicva[ion(no ond lincr) . <br /> Post-construction,pond fidl and lincd 1.76 __ <br /> 15cism o PS = 1.171 <br /> jPos[-construction,rapid drawdo�vn(no pond liner) _ L6G <br /> * Por static londing conditinns exeept�vhere nuted. . <br /> DISCUSSION :AV� IZLCO�IMLND:��lONS <br /> 13used an tlie results of our evaluation, it is ow� opinion diat tlic plar.necl pond const;uction, from a geotcchnical <br /> ; standpoint, ���ill not adversely impact the benn containing the nater main. [n addition, provided our <br /> recommendations a:e lollo�ced, pond construc[ion will increase [he stability of both the northem and southem <br /> � slopes of the berm. Conclusions and recommendations pertainin� to pond and berm design and construction are <br /> i prescnted below: <br /> • The pond's foundation soils con,i,t of inedium dense to dense silty sand and sand �cith silt. Based on the <br /> ( competent nature nf these soils, it is our opinion tlie risk of seil liquefaction and ra,ultin; berm <br /> � foundation failure or liquefaction-related setdements is negligible. <br /> � • Thc stability mode� inaicates tliat, widt respect to static loadina conditions, bertn slopes a[the locations of <br /> � the cross-sect�ons are st�Ule in tlieir current contieurations(before cunstruction case). Huwever, marginal <br /> stability is indicated���hen horizonta!ground accelerations from the design earthquake are modeled. <br /> � • Pond conswction will both reduce!he height and flatten the angle of the north berm slope. Accordingly, <br /> as shavn by rclativeh� hieh safety factors obtained in the stability analysis, pond gradin_ ��•ill result in a <br /> ,table nohhem Uemi slope. <br /> • �1'e recommend stripping and remu��ing of surface vegetation and or�anic surface soils from the pond <br /> area prior to placin� structural filL In ow� opinion, the asphalt layer may be left in placc prior to fill <br /> placcment. Duc to eh: poor cundition of the asphalt, it �vill not be suitable for use as a liner on the face of <br /> thc benn. <br /> Project No. T-»G9 <br /> , Page No. 4 ' <br /> i �lC� <br />