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© Mr. Robert J. Sbevfing P.E. <br />Engineering Manager <br />Marsh 22, 2005 <br />Page 2 <br />Block Failure <br />Existing Slope Safety Factor: 1.27 <br />3H:1 V Slope SaEery Factor: 1.35 <br />Block failure search routines were limited to a search depth of about 20 feet which is consistent <br />with mos/failures observed both on the site in disturbed and undisturbed areas and off the site in <br />virgin ground. <br />Circular Failute <br />Existing Slope Safety Factor: 1.16 <br />3H:1V Slope Safety Factor: 1.18 <br />4H:1V Slope Sar`ety Factor: 1.30 <br />The results of the stability analyses are presented in Attachment B, Slope Stability Calculation. <br />The circular failure search routine was allowed to search freely both laterally and verdcallv. if this <br />is allowed, safety factors less than 1.30 axe calculated until a slope angle of 4H:? V are reached. <br />Although the regulations require [ha[ all reclaimed slopes have a safety factor of L30 or snore, we <br />must remember that the location of the phreatic surface used in the model is estimated, We must <br />also keep in mind that both disturbed and undisturbed slopes on and off the site fail evex~~ year as <br />part o~ the ongoing mass wasting process. Lastly it is would not be practical nor desirable to <br />regard slopes to 4H:1 V because more ground would be disturbed. <br />Based on the results of the back analysis and the local mass wasting processes, we propose that the <br />slope be left in it's current configuration. 'Fhe slope will be monitored on a regular basis as part of <br />the ongoing site monitoring required by the DMG as put of the post-reclamation monitoring <br />prugratu. The post-reclamation monitoring is required for a period of ten years prior to bond <br />release of the area. The monitoring will consist of visual inspection to ensure that the area <br />maintains a stable configuration. <br />If you hate any further questions regarding this issue, please feel free to contact me <br />Sincemly, <br />_lliccr, P.E. <br />Engineer <br />Attachments <br />cc: Jay James <br />aie/a,m, <br />