Laserfiche WebLink
• Porosity (represented as n) and void ratio (represented as e) was also tested: <br />ncoarse - 0.46 ecoarse = 0.85 <br />nslimes = 0.43 eslimes = 0.77 <br />The full results can be seen in TRI/Environmental's reporting attached as an appendix to this Exhibit C. <br />Tailings impoundment stability, factoring in pore pressures, was also considered. According to Vick's Planning, <br />Design, and Analysis of Tailings Dams (pg. 196): <br />"For upstream embankments raised no faster than about 15-30 ft/yr, excess pore pressures are <br />usually assumed to dissipate as rapidly as the load is applied, and staged-construction analysis is <br />usually not performed." <br />The proposed operation is well below this condition, averaging 10-12 ft. per year. Additionally, consolidation will <br />be monitored utilizing the previously described core sampling testing. <br />Advanced Terra Testing performed the work associated with testing the strength properties of the tailings. They <br />utilized ASTM D4767 Standard Test Method for Consolidated Undrained Triaxial Compression Test. The <br />Consolidated Undrained (CU) method is a more conservative approach, as compared to a Consolidated Drained test. <br />According to Vick's Planning, Design, and Analysis of Tailings Dams (pg. 58-59): <br />"Undrained shear strength implicitly accounts for the pore pressures generated by rapidly-applied <br />shear stresses, and is important in evaluating the flowlike behavior exhibited by many tailings <br />deposit failures." <br />Using this CU analysis, remembering the 1.5 factor of safety in determining the maximum confining pressure of <br />15,000 lb1W and considering the relatively slow rate of tailings deposition; Venture Resources is confident the <br />• analysis provides for a very conservative result. <br />ATT's CU triaxial shear test results can be found in its entirety within the appendix of this Exhibit C. This data has <br />been digested to determine the Effective Friction Angle, YFA, properties of both the Coarse and Slimes Fraction for <br />varying confining pressures. According to Vick's Planning, Design, and Analysis of Tailings Dams (pg. 193): <br />"If pore pressures are measured during the CU test, an effective-stress [Mohr] envelope can also <br />be constructed." <br />Following are the Mohr envelopes and the resulting Effective Friction Angles developed from the data: <br />• <br />Page 22 of 35