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Memo to Erica Crosby 2 Mazch 13, 2006 <br />Pazker/Dersham Pit Mining Setbacks Permit No. M-2006-003 <br />3. In the summary letter the applicant assumes that the claystone bedrock has a peak cohesion of <br />100 psf. However, in the XSTABL output, cross-sections A-A' thru F-F' were analyzed using a <br />cohesion of 1,000 psf. The analyses must be run using a cohesion of 100 psf for the claystone <br />bedrock to confirm a FOS of greater than 1 for each of the cross-sections. <br />4. The location of cross-section F-F' is unclear. The description given in the summary letter <br />indicates that cross-section F-F' "...considers the closest distance to WCR 23.5 along the <br />southem mazgin of Phase 3". According to the figures, WCR 23.5 borders the western margin of <br />the site, not the southem mazgin. In addition, Table 1 describes section F-F' as being located in <br />"South Phase 2" with the critical structure being the Gas Well/Pipe. As indicated in Item No. 1 <br />above, the locations of the cross-sections must be indicated on at least one figure. <br />5. No stability analysis was made for the southem border of Phase 3 where the proposed excavation <br />will pazallel WCR2Baseline Road/168`h Avenue. Because WCR2Baseline Road/168`~ Avenue <br />is a significant man-made structure located within 200 feet of the mining limits, a stability <br />analysis of this structure must be made to evaluate the stability of the structure during mining <br />operations. <br />cc: Carl Mount, DMG (via email) <br />C:\RMW~2006 PermitsVN-2006-003\Parker Dersham Pit Stability.doc <br />