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Ralston Quarry Slope Stability <br /> Ralston Quarry <br /> Slope Stability Analysis <br /> Section C-C' 1.03 <br /> 2eo <br /> 2w <br /> NO <br /> 220 <br /> 200 <br /> N ISO <br /> 01 <br /> S 160 <br /> C <br /> o /Im Tailings' unit Weightrl Angle <br /> =3 pcf <br /> lL '� Friction =�a <br /> i <br /> Couvium Cohesion=100 par <br /> Ip— Unit W090 125 pd <br /> j CDhem n-1=ps <br /> � </ Coheaian=135 psf <br /> Claystorle <br /> m Unt Weight=130 pcf <br /> Friction Angie-20° <br /> m Cohesion=1.000 psf <br /> o ._. <br /> 0 M M 150 200 250 300 750 00 50 500 550 600 <br /> Distance(feet) <br /> Remedial Measures Similar to Zone 3, in GROUND's opinion, in order to increase the <br /> factor of safety against failure in Zone 4, two stability embankments should be <br /> constructed along the slope across the entire north to south width of the zone. The <br /> excavations to construct the embankments should be extended through the colluvium an <br /> into in-place shale (into firm, weathered shale is sufficient) to interrupt the low-strength <br /> layer of colluvium underlying the tailings. This geometry is shown on the SlopeW <br /> output on the following page. The stability embankments are shown in green. Stability <br /> analyses of this geometry indicated a Morgenstern-Price factor of safety against failure <br /> of about 1.3. <br /> The stability embankments should be constructed of properly compacted granular <br /> material, similar to the tailings, exhibiting an angle of internal friction ((�) of at least 35 <br /> degrees and an effective cohesion (c) of at least 100 psf. <br /> Geotechnical parameters for embankment construction are provided in the Project <br /> Earthwork section of this report. <br /> Job No. 18-3046 GROUND Engineering Consultants, Inc. Page 20 <br />