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3.2.2 Gravelly Sand and Poorly Graded Sand Stratum <br />The gravelly sand stratum was assumed to be a medium dense to dense gravelly <br />sand and poorly graded sand beginning at elevation 20 feet MSL. Some sand <br />layers in this stratum were cemented. For static and seismic stability, the grav- <br />elly sand and poorly graded sand strata was assumed to be weakly cemented <br />and to have a 450 psf cohesion, a friction angle of 37 degrees, and a total unit <br />weight of 125 pcf. <br />3.3 LINER SOILS <br />A 1 -foot -thick clay liner is planned for the landfill. Landfill lining requirements <br />have been described in Section 10.1 of the Report of Disposal Site Information <br />(RDSI), EMCON, 1989. Laboratory strength data were not available for the clay <br />liner soils because borrow sources have not been identified. For long term static <br />stability, the clay liner was assumed to have zero cohesion, a friction angle of <br />22 degrees, and a total unit weight of 120 pcf. For short term static and seismic <br />stability, a cohesion of 800 psf and a friction angle of zero degrees were <br />Is assumed. EMCON recommends future laboratory testing of representative clay <br />liner soil samples to confirm soil strengths used in the stability analyses. <br />• <br />3.4 FINAL COVER SOILS <br />Final cover soils are planned to include a 1.5 -foot -thick upper layer for planting <br />and vegetation, a 1 -foot -thick low permeability layer, and a 2 -foot -thick foundation <br />layer. Laboratory strength data are not available for the final cover soils because <br />borrow sources have not been identified, and the final cover has not been de- <br />signed. Future laboratory soil testing and slope stability analysis will be required <br />for the final cover. <br />PJ9 9390217.00W 8 Rev. 0 May 23, 1989 <br />