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• J.E. Stover & Associates <br />Terracon Project No. 65995058 <br />June 3, 1999 <br /> ,::::::, <br /> <br />.._., <br />. ...:. . <br /> <br />= .rained:.=.. <br />D <br /> <br />:: n rainedShear;: <br />.: . <br />;; Slope :::. :: ...::: <br />.:. ., Soil;':::-: .::::::: <br />_ :Strength::::;:. . <br />::;.::..Strerigth.:.:. <br />- <br /> <br /> <br />Location <br />.:. x <br /> <br />~;;:: <br /> <br />ype <br /> <br />Parameters <br />. <br />- <br />Parameters <br /> <br />~... ~,: ~~ <br />u~;:. ,,,~::::.: C,.~ ~~,;-. <br />Foundation Soils Clay (CL) 250 30 2200 4 <br /> Sand & Gravel (SP-GP) n/a 34 n/a 34 <br />Embankment Fills Lean Clay (CL) 250 30 1500 0 <br />STABILITY MODELS <br />For purposes of our stability evaluations, cross-sections of the proposed cuts and/or fill <br />sections for each structure were developed on the basis of the existing and proposed final <br />contours shown on the Site Plans (Slope-1 and Slope-2) by J.E. Stover & Associates. Five <br />• cross sections were developed on the basis of the proposed grading. These included one <br />section at the location of the proposed Transfer Station Pad (Section CC), two at the locations <br />of the proposed fill slope and cut slope at the proposed coal stockpile (Sections AA and BB), <br />and two at the location of the proposed sedimentation pond (Sections DD and EE). Both the <br />upstream and downstream faces of the pond embankment (Section EE) have been included in <br />the models. These sections were taken at locations of maximum slope height in either cut or <br />fill sections. The locations are depicted on Figures 1 and 2 attached. <br />Stability evaluations for the proposed transfer station and coal stockpile slopes have been <br />analyzed for three potential cases that include <br />• Case I: Temporary-End of Construction (undrained shear strength analysis) <br />• Case II: Long-Term (consolidated-drained shear strength analyses) <br />• Case III: Long-Term with static groundwater conditions <br />To simulate potential static groundwater conditions, phreatic surfaces have been incorporated <br />into each model, generally located at the level of the underlying sand and gravel soils. Under <br />operational conditions, the proposed sedimentation pond is expected to fill and empty within a <br />three-day time span. Long term storage of storm water is not anticipated. Based upon the <br />relatively short detention time of water in the sedimentation pond, development of steady state <br />• seepage and a full phreatic surface through the embankment fill is not anticipated. However, <br />6 <br />