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<br /> <br />Laboratory Testing <br />The results of the laboratory testing pertormed are presented in Appendix A <br />and summarized on Table A-I. Following is a discussion of the test results for each <br />major soil type found. <br />Clays. The clay soils were sandy to very sandy with 52 to 64 percent passing <br />the No. 200 sieve for the samples tested. The samples exhibited low plasticity, <br />with liquid limits of 27 to 33 percent, and plasticity indices of 11 to 17 percent. <br />A combined sample of the clay soils was selected for direct shear and <br />standard Proctor (ASTM D 698) testing. The strength values were determined <br />for a remolded sample compacted to approximately 96 percent of standard <br />Proctor maximum dry density at a moisture content about 2 percent above <br />optimum. The results of the direct sheartest indicated a peak shear strength <br />of 19 degrees with 920 psf cohesion. Residual strength values were 21 <br />degrees with a cohesion of 490 psf. <br />Clayey Sand. The clayey sand soils tested contained 25 to 41 percent <br />• passing the No. 200 sieve with a liquid limit of 28 percent and plasticity index <br />of 14 percent. <br />Gravel and Sand. Two samples of this material were tested and contained 40 <br />to 60 percent gravel and cobble, with 10 to 14 percent passing the No. 200 <br />sieve. For standard Proctor and permeability testing, the + 314 material was <br />proportionally replaced in the bulk sample with #4 to 3/4-inch material to <br />reflect the gravel portion in the test sample. For this reconstituted bulk <br />sample, permeability testing indicated permeability on the order of 2 x 10'' <br />centimeters per second. This indicates a relatively permeable material. <br />STABILITY ANALYSIS <br />Site conditions at the various embankment configurations were evaluated to <br />develop two models to represented conditions for the six embankments under <br />consideration. At 5 of the 6 sites, the existing grade in the area is slightly sloping, <br />with existing grades on the order of 2 to 9 percent. The maximum embankment <br />height is 10 feet. The slope at Pond 013 is moderately sloping, with a slope on the <br />order of 15 percent. At this location the embankment height on the upstream side is <br />• 6 feet. Based upon these conditions, the general model shown on Fig. B-1 was used <br />LORENCITO COAL COMPANY, LLC <br />SMALL SEDIMENTATION EMBANKMENTS <br />CTLR 46,559 7 <br />