2010-06-02_REVISION - C1981019 - Laserfiche WebLink

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The opening paragraph of Revised Addendum No. 3 makes it clear that Revised Addendum No. 3 takes precedence over all previous geotechnical reports in regard to slope stability and material strength properties. 29. The overall footprint of the Excess Spoil fill areas does not appear to have been revised between the July 2006 Study and the first two Addenda. Significant changes are proposed, however, with Addendum No. 3, dated October 21, 2009. The spoil configuration has been revised, and outslopes have been steepened, to allow sizable temporary spoil fills to be placed over the permanent spoil fills. Additional laboratory testing has been performed on spoil and clay soil overburden, and on the Carbonaceous Mudstone (CMS) layer exposed on the floor of the pit. New Figures 1 thru 6 are presented, along with a new Appendix A. There is potential for future confusion with respect to the new "Addendum" (Addendum No. 3). Addendum No. 1 and Addendum No. 2 consisted of minor modifications to the original Shannon and Wilson Study and updated specific Figures or Tables, while maintaining the original order of the figures. Addendum No. 3 includes a new set of Figures (1 thru 6) that do not correlate with Figures 1 thru 9 of the July 2006 Study. A new "Appendix A" has been provided, which does not appear to be designed to replace the current Appendix A. If Colowyo wishes to name the October 2009 study "Addendum No. 3", the Division suggests renumbering the accompanying Figures beginning at "10" and changing the Appendix from "A" to "D". Alternatively, it may be simpler to eliminate the "Addendum" reference and give the current study its own title. Please revise the contents of the October 2009 Shannon and Wilson study (Addendum No. 3) to correlate with the existing Exh. 21, Item 1 Study, or eliminate the "Addendum" tie to the previous Study. Response: Because of the potential for confusion among the several reports and addenda, we have elected to make the Revised Addendum No. 3 the governing document with regard to all material strength properties and slope stability. Table references and figure references within the April 15, 2010 Revised Addendum No. 3 are all internally consistent. Also, Shannon and Wilson has renumbered all figures in Revised Addendum No. 3 to start with Fig. 10 and re-named the Appendix to "D" as suggested above. Revised Addendum No. 3 is thus entirely consistent within itself and no longer presents the possible confusion to previously numbered figures and appendices. 30. The Division has noted certain discrepancies in the data presented in Table A-1 - Results of Stability Analyses - Section A-A' as follows: The CMS Cohesion value for Trials 1 and 2 is listed as 750 psf, when it should be 706 psf (per Page 2 of the text). This may be a misprint in the table only; the correct value appears to have been used in the Slope/W software (pp 22 and 23). CMS Friction Angle and Cohesion values for Trials 5 thru 8 should be 17 and 706 (Mean Parameters) rather than 14 and 288. Slope/W printouts have not been provided for these Trials, so the Division was unable to determine whether correct values were used to compute the Factors of Safety reported. Please review Table A-1 entries and revise as