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specifications for placement in the buttresses. As shown in Appendix 1, Designed Fill material <br /> met or exceeded requirements for compaction and moisture with rare exceptions. <br /> Table 3— Material Properties <br /> Material Unit Weight(pcf) Friction Angle(deg) Cohesion(pcf) <br /> Tailings 125 35 100 <br /> -------- <br /> Colluvium 125 22 135 <br /> Shale Bedrock ' 130 20 1000 J <br /> Designed Fill 125 35 100 <br /> 3.1 Earth Materials <br /> Depth and extents of pre-slide soils was determined based on Ground Engineering test holes and <br /> drilling that took place in and around the slide area following the slide. In general,these tests <br /> describe a natural colluvium layer atop of shale bedrock that was then covered in a tailings layer <br /> by early earthwork in the area. Each Zone identified during the slide repair has different layering <br /> of colluvium and tailings. This variability of material thickness and depths has been the cause of <br /> the majority of design adjustments during construction; excessively deep excavations below a <br /> loaded slope present safety and construction risks that must be mitigated by design adjustments <br /> in the field. <br /> Zone 2 has roughly 20 feet of colluvium overlain by about 15 feet of tailings on the slope,with <br /> tailings thickening down slope towards Zone 1. Zone 3A has roughly 10 feet of tailings <br /> overlaying 5-10 feet of colluvium. Zone 313 has 15-30 feet of tailings/Designed Fill over 5-20 <br /> feet of colluvium. Zone 4 has roughly 10-15 feet of tailings/Designed Fill over 0-5 feet of <br /> colluvium. Zone 313 colluvium and tailings combined depth is in believed to be in excess of 40 <br /> feet in some areas. <br /> 3_2 Water Presence <br /> Perched groundwater is not present within the colluvium or tailings unless a hydrologic block is <br /> in place at the slope toe. This was confirmed during construction by both APC,their construction <br /> contractor, and technical support staff from Ground Engineering. Following snow melt and rain <br /> events, moist ground was noticed but no standing water within the slope areas. At no point did <br /> construction involve any dewatering of subsurface inflows to create a dry construction area. <br /> Springs and seeps have been identified along the toe of the slope in the past near the natural draw <br /> and will continue to be present due to the permeability of the colluvium and the tailings. <br /> Additionally, the presence of the subsurface drainage pipes will ensure that infiltrated surface <br /> water is not trapped within the slope material. Therefore, all analysis of the slope assumes that <br /> the piezometric surface within the slope is along the shale until or below the lowest drainage pipe <br /> discharge. <br /> The cross sections in Appendix 2 show each Zone in its final construction condition. These cross <br /> sections are the basis for all slope stability analysis conducted. <br /> Ralston TR 03 8 Greg Lewicki and Associates.PLLC <br />