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2.2.5 Verification of Colluvium Properties <br />The inclinometer measurements from June 28, 2012 to January 21, 2013 were used to confirm the in- <br />situ Young's modulus from earlier analyses. Shear strength envelopes from the Fall 2013 fully <br />softened and residual shear strength testing were used directly in the FLAC model for the Lower and <br />Upper Colluvium, respectively. <br />The laboratory shear strength envelopes based on the Fall 2013 drilling program, in addition to the <br />interpreted design envelopes, are shown in Figures 2-3 and 2-4 for the Lower and Upper Colluvium, <br />respectively. The laboratory testing results used to develop these envelopes, including index testing <br />and shear strength testing, are shown in Appendix B. <br />The resulting deformations predicted by the model compared to the deformations as shown in <br />inclinometer I12-04 are shown in Figure 2-5. Figure 2-6 shows the cumulative relative displacement <br />between the depths of 35 and 57 feet as a function of time for the inclinometer readings and the <br />FLAC analysis based on laboratory data. It can be seen from Figures 2-5 and 2-6 that the there is a <br />very good match between the inclinometer data and the deformations produced in the FLAC <br />modeling. Table 3 shows the properties for these materials. <br />The Young's modulus for the Upper and Lower Colluvium is in the typical range for soft and stiff <br />clay soil, respectively. <br />The boring logs associated with this work are provided in Appendix A. <br />2.3 Assessment of Stability <br />Assessment of compliance with stability factor of safety requirements was completed for both the <br />target design slopes presented in the permit drawings, and for a "permit envelope" to establish a <br />maximum acceptable slope that meets stability factor of safety requirements to provide some <br />flexibility in the final construction of the waste rock pile. The results of the two assessments are <br />summarized in the following sections. <br />2.3.1 Assessment of Stability — Design Slope <br />Using the colluvium properties shown in Table 3, two-dimensional (21)) stability calculations were <br />performed using the current and projected RPEE waste rock pile geometry as shown in Figures 2-7 <br />and 2-8. Three-dimensional (31)) effects were taken into account by following the procedure <br />11 <br />P:\Mpls\06 CO\26\06261003 MCC Refuse Pile Site Review & Permit\WorkFiles\Permit Application\2014 Revision\Exhibit 82 2014-05- <br />29.docx <br />