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JUL 01 '99 11~32RM PERBO~WSTN SENECR MINE • P.2 <br />Mr. Mm6.JBury <br />INwia JMaer+G ad Gdgy <br />fdJ' 1, 1999 <br />Age 2 <br />July 1st Respouset Based on our phone conversation earlier roday the Division needed furdus <br />cluiEcation on this response. The first si: hundred ket of Haul Road 'D' is gseatec than 10%, which <br />mesa the ccireria of the adequacy comment. Attachment 13-5, Geotechnieal Investigation, contains <br />several stability analyses for the designed cut and fill sections along Haul Roads 'A' and 'B'. SCC <br />pointed out that the cut and fdl slope designs Eor the r.nm~n~ng haul made mould not exceed the <br />existing designs contained in this attachntettt and the seat in Tab 13. We based this statrment on the <br />following two facts. Fast, that the existing roads have not shown any signs of instability since they <br />were constructed in 1995. Secondly, that the haul mad conatmcoon rnateuals and sol atrertgdt <br />properties for the remaining south areas at Yoast are similaz ro those for the areas dolled and analyzed <br />previously. This type of approach and analysis was acceptable foe sedimentarion pond 012. Therefore, <br />a toad cut slope will not be steepec than 1V:1.5H in unconsolidated mattsial or 1V:0.25H in rock. <br />Lmbankttuttt fill slopes w>71 not 6e steeper dtan 1V:2H foe these proposed roads. The vertical grade <br />of a section of haul road, whether it be 9at(0% grade) or in the case of Haul Road 'D' at 15.0%, has <br />no bearing on the factor of safety calnilation for a partinrlar section of road. The vertical grade is for <br />erosive velocity conditions only. For the 'purposes of demonsenting this fact, SCC will commit ro and <br />provide the Division with a stability analysis specifically for this road section of Haul Road'D'. <br />Sincere~ly~, ~ ~ ~ y~ //+~ ~~Q~~ <br />Michael G. Alnvilla, P.E. <br />Engineering Manager <br />cc: j. Husband (BLM) <br />L. Kline (OSMRE) <br />