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Earth Engineering Consultants,LLC <br /> EEC Project No. 1212092 <br /> November 23,2021 <br /> Page 5 <br /> Sand with Gravel <br /> The overburden soils were underlain by sand and gravel which extended to the underlying bedrock. <br /> Select samples of the sand and gravel subgrades were tested in the laboratory for plasticity, grain <br /> size distribution, and shear strength parameters.In general,the sand with gravel soils were poorly <br /> graded to well graded and generally contained low and variable silt content. Direct shear testing <br /> on two (2) samples indicated ultimate shear strength parameters (friction angle, 0 and cohesion, <br /> Q of 30°and 0 pounds per square foot,and 31.9°and 275 pounds per square foot,respectively. <br /> ANALYSIS AND RECOMMENDATIONS <br /> The stability of two sections were evaluated as requested. Those sections included a Non-Critical <br /> Structures section and Critical Structures section.Both sections assumed a minimum setback from <br /> the top of the cut slope to the permit boundary of 50 feet. The Critical Structures section also <br /> assumed a surcharge of 2,000 pounds per square foot setback 50 feet from the top of the cut face. <br /> The analyses assumed a maximum 42-foot excavation depth which would extend to bedrock, and <br /> continuous dewatering at the base of the excavation. Based on the subsurface conditions <br /> encountered and the geometry of the proposed excavation, stability analyses were carried out to <br /> determine the maximum allowable slope for the cut face to satisfy the minimum required safety <br /> factors. <br /> The stability analyses were evaluated using Morgenstern-Price method of slices modeled in <br /> SLOPE/W software provided by GeoStudio. Porewater pressures were modeled using SEEP/W <br /> software. Soil parameters used in the analyses were obtained from the conditions observed, the <br /> results of laboratory testing, and/or estimated from available geotechnical information. Shear <br /> strength parameters used for the overburden soils included an assumed friction angle of 250 and <br /> cohesion of 100 pounds per square foot.For the sand with gravel,an average friction angle of 31° <br /> and average cohesion of 138 pounds per square foot was used. The results of the slope stability <br /> analyses for Non-Critical Structures are shown in Figures 1 through 4,and for Critical Structures <br /> Figures 5 through 8. The safety factors associated with the analyses are summarized in Table 1. <br />