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Memo to Michael Cunningham 2 Sept 16, 2010 <br />Slope Stability Review File No. M-2010-047 <br />Cross Section No. 1- County Road 37 <br />The applicant's cross section was modeled with the addition of the topsoil stockpile as represented on the <br />Mining Plan Map. The safety factor produced by Galena is lower than that produced by the applicant's <br />formula; however it was well above the normal long term safety factor of 1.3. Therefore, the accuracy of <br />the applicant's analysis is confirmed (see attached). <br />Cross Section No. 2 - County Road 96 <br />The applicant's cross section was modeled as represented on the Mining Plan Map. The safety factor <br />produced by Galena is lower than that produced by the applicant's formula; however it was well above <br />the normal long term safety factor of 1.3. Therefore, the accuracy of the applicant's analysis is confirmed <br />(see attached). <br />Conclusion <br />The DRMS agrees with the proposed setback from County Road 37 and 96 at the Lone Tree Pit. The <br />excavation along the east and north sides of the pit adjacent to the county roads must never occur within <br />30 feet of the county road right-of-ways, exceed a slope of 3H:1V, groundwater will not be intercepted at <br />the proposed maximum mining depth of 20 feet and the site soil profile consists of SP (poorly-graded <br />sand). If groundwater is intercepted shallower than expected and/or the soils differ from the expected <br />profile, the applicant must contact the DRMS immediately and reevaluate the stability analysis based on <br />the corrected information. The permit applicant must understand that any transgression of the 30 foot <br />buffer or sloping criteria will be considered a serious violation of the permit if it is approved and issued. <br />Enclosures