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M99012GE <br />5/2/99 <br />Page Three <br />• the entire mass is determined by summing the driving and summing <br />the resisting forces acting on all slices and comparing these <br />forces. <br />Our slope stability analysis was performed using "Slope Stability <br />Analysis" by Geosoft computer software. Our slope stability <br />analysis considered one (1) glanned cross section as a completed <br />GOB fill which was provided by Mr. Jim Stover. Our analysis <br />included a total of about 1,400 separate possible failure surface <br />iterations to help identify the potential minimum theoretical slope <br />stability for the conditions assumed. Our discussions and data <br />presentation are based only on the calculated critical circle which <br />presented the lowest factor of safety against failure. Our <br />presentation does not include the results of all of the iterations <br />which resulted in a theoretical factor of safety greater than the <br />lowest factor of safety and therefore were not critical. <br />Our analysis was based on soil strength characteristics obtained <br />from laboratory triaxial compressive strength tests of samples of <br />GOB material encountered in our test borings obtained during our <br />field study and soil strength data of the underlying foundation <br />soil materials presented in the Westec reports. The soil strength <br />values used in our analysis included: <br />• Low density GOB material: <br />. an internal angle of friction of twenty-one (21) degrees, <br />. cohesion of three-hundred-seventy-five (375) pounds per <br />square foot, and <br />. a moist unit weight of eighty (80) pounds per cubic foot. <br />GOB compacted to at least 90 percent (ASTM D698) relative <br />compaction: <br />an internal angle of friction of twenty-two (22) degrees, <br />cohesion of five-hundred (500) pounds per square foot, and <br />a moist unit weight of one-hundred-ten (110) pounds per cubic <br />foot. <br />Site soil material underlying the GOB fill, based on information <br />provided in Westec report dated January 1996 and February 12, 1997: <br />an internal angle of friction of thirty-two (32) degrees, <br />a cohesion of seven-hundred-fifty (750) pounds per square <br />foot, and <br />a moist unit weight of one-hundred-twenty-five (125) pounds <br />per cubic foot. <br />i <br />~iambert ana ~,oooriates <br />GONSUL TiNG GEOTECN NiC~L ENGINEERS •ND <br />M.~LE RILL TESTING <br />