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M03030GE <br />Stover with a total of about 1,600 separate possible failure <br />surface iterations for the cross section to help identify the <br />potential theoretical slope stability. Our discussions and data <br />~ presentation is based only on the calculated critical circle which <br />presented the lowest factor of safety against failure. Our presen- <br />tation does not include the results of all of the iterations which <br />resulted in a calculated theoretical factor of safety greater than <br />the lowest factor of safety and therefore were not critical. <br />The cross section included .in our stability analyses are A-A of <br />the "As-Built Contour Map, West Mine" drawing number C-81-038 dated <br />November 4, 2002, as provided by Mr. Stover. We assume that the <br />drawings showing the location of the cross sections are available <br />through Mr. Stover's office therefore these are reproduced only in <br />part in this report to present geotechnical engineering information <br />only. <br />Our analysis was based on soil strength characteristics obtained <br />from laboratory triaxial compression test of samples tested ob- <br />tained during our field study. The soil strength values used in <br />our analysis included: <br />Existing natural undisturbed formational material (assumed): <br />. an internal angle of friction greater than thirty (30) <br />degrees, <br />~ cohesion of at least two-thousand (2000) pounds per <br />~ • square foot and <br />. a moist unit weight of one-hundred thirty-five (135) pounds <br />per cubic foot. <br />Existing fill soil material: <br />an internal angle of friction of five (5) to seven (7) <br />degrees, <br />cohesion of one-thousand two-hundred (1200) to one-thousand <br />four-hundred forty (1440) pounds per square foot and <br />a moist unit weight of one-hundred twenty-five (125) pounds <br />per cubic foot. <br />Our analysis of the existing reclamation fill slope assumed <br />undrained conditions. We anticipate that with time the fill may <br />become saturated from precipitation infiltration into the fill <br />material and becoming perched on the formational material. <br />In our stability analyses we varied the soil strength values as <br />listed above to assess the sensitivity of the analysis to varying <br />soil strength parameters. The variations in our analysis produced <br />relatively predictable changes to the calculated theoretical factor <br /> <br />~llam6ert ana ~~',oociateo <br />CONSULTING GEOTEON NIO~L ENGINEERS eNp <br />M•TERUL TESTING <br />