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i`��`3'i k1vJJlr,iuu•I1e3n <br />None of the shear strength testing shows a (trained 1Tlctlon angle as low its 30 °, <br />HBET does not believe that tills value is representative of the gob and as a result, <br />sensitivity analyses using tilts value is not warranted, Flowever, for conservatism, HBET <br />conducted sensitivity analyses considering a drained friction angle of 32 °. The results <br />indicate that Gob Pile #2 at both cross sections Nvill still leave a factor-of- safety above 1.5 <br />Pore Pressures <br />With regard to sensitivity of the analyses to changes in bore pressures, the <br />piezotneteric surface was changed by adjusting the pore pressures in piezonleters VWP - <br />05, VWP -06, and VWP -08. The results of the sensitivity analyses indicate that tine <br />stability of gob pile #2 with the covet-fill stockpiles is most sensitive to changes in pore <br />pressures in VWP -05. For both Sections A-A' and B -B', an increase iI] pole pressure of <br />4 psi (equivalent to approximately 9 feet of head) would result in a factor of safety of less <br />than 1.5. However, an increase in the pore pressure in VWP -08 of 9 psi (equivalent to <br />approximately 21 feet of head) would not reduce the factor -of- safety to less than 1.5 in <br />either cross section. In addition, an increase in the pore pressure in VWP -06 its much as <br />10 psi (equivalent to approximately 22 feet of head) did not significantly reduce the <br />factor -of - safety of gob pile #2 along either cross section. <br />3.6 Conclusions <br />As indicated previously, the analyses indicated that the placement of coverrill <br />stockpiles oil gob pile #2 will not adversely impact the stability of gob pile #2. However, <br />as indicated previously, changes in the pore water pressures could affect the stability. <br />The referenced monitoring data does indicate slight increases in the pore <br />pressures of VWP -06 and VWP -08. However, these increases are likely due to active <br />gob placement in the vicinity of these instruments and are much lower than the values <br />used in the sensitivity analyses. <br />At VWP -05, the monitoring data indicate that the pole pressures near the toe are <br />fairly constant, While placement of coverfill neap the toe may cause slight increases in <br />pore pressures at the toe, HBET (toes not believe that tine increases will be sufficient to <br />cause instability in gob pile 42. However, quarterly monitoring of the piezometers is <br />reconvnended to identify any significant changes in pore pressures which may impact the <br />stability of gob pile 42. <br />4.0 GENERAL <br />This conclusions, results, etc. in this report is based upon the information in the <br />referenced documents, current analyses, and on our experience with Similar projects. The <br />conclusions are valid only for the subject project. <br />Huddleston -Berry Engineering and Testing, LLC is pleased to be of service to <br />your proiect. Please contact us if you have any questions or comments regarding the <br />contents of this report. <br />\'3003 ALLPROJECTS '01'44- €lostiir Resources, L1.0 013-19 -6901 BmNit Mine WO- Uw'Gob 2'Coeei rill Stabilkr 013.14 -0401 RG9191.1; doc 5 <br />