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Both the USSA and ESSA were performed as part of the slope stability analysis at Monument Dam. <br />8.2.1 Geometry <br />The geometry of Cross-Sections B and C is described in detail in Section 8.1.1 above. <br />8.2.2 Parameters <br />Field and laboratory testing data as well as model calibration (back-analysis) along with engineering <br />judgment were used to develop representative parameters for the analysis of Monument Dam. <br />Laboratory data include direct shear (DS) and triaxial (TX) testing. Table 6 summarizes the shear <br />strength parameters for slope stability modeling of existing conditions and proposed <br />remediation/stabilization measures at Monument Dam. <br />Table 6 Summary of Strength Parameters for Dam Stability Modeling <br /> Undrained USSA Drained ESSA <br /> <br />Mohr-Coulomb Strength <br />Ratio <br />Mohr-Coulomb <br />Residual <br />Material c [psf] C1 de Ratio c' [psf] de ,' de . <br />Existin Materials <br />Embankment Material 0 25.8 - 0 32.2 - <br />Soft Sediment - - 0.23 Non-linear' - <br />Colluvium^ 2,000 0 - Non-linear - <br />Failure Surface Material - - - - - 17.5 <br />Weathered Bedrock# - - - - - - <br />Pro osed Materials <br />Buttress Material 0 32.2 - 0 32.2 - <br />Downstream Draina a Blanket 0 30.0 - 0 30.0 - <br />U stream Cla Blanket 0 32.2 - 0 32.2 - <br />"-see Figure 9. <br />' ^-See description in Section 8.2.2.4 <br />®-See Figure 10. <br />#-This material was assumed to be infinitely strong in the model. <br />' 8.2.2.1 Unit Weight <br />Unit weights were selected based on saturated natural water content values from lab testing for <br />saturated unit weights and assumed water contents for moist unit weights. Table 7 shows the unit <br />' weight values used in the analysis. <br />P:\Mpls\06 CO\26\0626067\WorkFiles\DesignReport\FINAL\DesignReportFINAL.doc <br />25 <br />