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r~ <br />07108/2004 15:13 19703822515 <br />LAMBERT ASSOCIATES <br />CONSULTING GEOTECHMICAL ENGItrEBRS ttNp lNATBRIALS TESTING <br />San Juan County Commissioners; <br />P.O. Sox 466 <br />Silverton. Colorado 81433 - <br />Subject: <br />Eureka Gravel Pit <br />June 4, 2004 Cursory Site Observations <br />Eureka, Colorado <br />~Gl <br />R@~~`~ <br />7 ~ <br />?1~~~ <br />PAGE 02 <br />July 7, 2004 <br />PN: D04ISSGE <br />Coqunissioncrs, ... <br />21tis.letter is in response to our July 6.2004 tctephoru conversation with Mr. Louie Giro, Sau Juan <br />' County%Road Aep~ri'mcirt end.presrnts our cursory obsmations of the burelca Gravel Pit and nc~ slope <br />". areas above the gravel pit. The observations were conducted with Mr. Girpda on June 4, 2004. 4~e <br />$riefly discussed ow observations with Mr. Wally Erickson, Colorado Department of Minerals and <br />'Fieology on June 1 1, 2004. Our proposal #or a geotechnical rngineering slope stability analysis is <br />presented scparacely:. <br />W8 understand that no graver mining at the pit has occurred since 1998. The grevel mining operation <br />included excavation 8f material along the tce of an extensive talus slope. '[rte natural slope inclination of <br />the talus scope is estimated to be about thirty-five (35) so forty (40J degrees. San Juan County Road 25 <br />` exists midway up thz talus slope and provides recreational access to I:uteka Gulch. <br />The mining operation has aver-stcepen~ the slope .which has destabilized the talus and has initiated <br />erosion. The talus is"raveling" up slope of the mined area which has produced a toad scarp a few <br />hundred feet below County Road 25. 7'he hrad scarp wj-1 most likely continue its upward progression <br />until eventually it wt71 influence County Road 25. It does not appear that [he rate of ttp-slope progression <br />is rapid. ' <br />Doting August of 2003 a severe thunderstatnh hit the sauttiwestern Colorado atra. We understand that <br />during this event that County Road 25 was coveted with a mudslide from above. This event apparently <br />.did not significantly influence the eroding slope arcs above the gravel pit. Bawd on the historical <br />performance of the slope it does not appear that a catastrophic immediate failvrc of the slope and <br />roadway is imminent. If there is a catastrophic failure it does not seem that the potential hazard created <br />by such nn event would be significantly dif7eretit than natural hazards created on the alpine roadways ' <br />throughout San Juan County, Colorado. <br />Please cor ~ u have any questions. or if we may be of additional service <br />....~ _- <br />p.0. aOX )9~6 e.D. aox DOaS ~ 314 Bodo Drive <br />GRAND JUNCTr4N,?C CG ^' MDNTROSE~ CD [1402 DURANGO, CD. B1D01 <br />(9701 245-a FO,Q-~ t9t0) tas-r15d (9'+01 .59-5095 <br />k a' <br />