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March 3, 1997 <br />-5- 963-?178400.410 <br />4.0 POST-RECLAMATION STABILITY <br />Slope stability analyses were performed on nine sections using post-reclamation <br />topography. The results of the post-reclamation stability analysis are shown below: <br /> <br />;;:.;:.:;;:;::::`: I:oeatton:'of::Section ::• :::::.:.::::.:•:.;:' ;r:; Factor:of:Saf <br />'ESo~E:Paratnetiers):: <br />Haul/Access Road -Section A-A' 1.7 <br />Haul/Access Road -Section B-B' 2.0 " <br />Water Tank Area -Section C-C' 1.6 <br />Haul/Access Road -Section D-D' 1.8 <br />Water Tank Road -Section E-E' 1.5 <br />Substation -Section F-F' 1.3 <br />Haul Road -Section G-G' 1.6 <br />Sediment Pond -Section H-H' 2.0 <br />Shaft Site -Section I-I' 1.8/I.0* <br />' The factor of safety depends on whether the cut is laid back or cut at 70°. A factor of <br />safety of 2.0 was obtained assuming the cut was in bedrock, which assumed parameters of <br />c = 2000 psf and ~ = 40°. <br />As with post construction stability analysis, factors of safety are based on assumed soil <br />strength parameters that will be better defined following the proposed geotechnical <br />investigation. Because the slopes will be flattened or buttressed, post reclamation stability <br />will be at least as good as the post construction stability as indicated by the above tables. <br />5.0 CONCLUSIONS <br />The following conclusions can be made concerning the slope stability analyses performed <br />by Golder for the Sylvester Gulch Facilities: <br />- Qualitative slope stability analyses were conducted to estimate the factor <br />of safety for the constructed slopes along the Sylvester Gulch access <br />road alignment, substation site, and shaft site. These analyses were <br />performed using material properties estimated from previous <br />investigations, and reference material, <br />- A geotechnical investigation will be performed to estimate the material <br />properties and ground water elevations in the Sylvester Gulch Facilities <br />Area at specific facility locations, <br />- The on-site Engineer will be responsible for determining if the factor of <br />safety for a given slope falls below accep[able values during <br />su~:~%,:nezneewq o« Golder Associates <br />