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Cod <br />07/08/2004 15:13 19703822515 <br />LAMBERT ASSl7CIATES <br />~TCt~i¢T t ~[Tt~ ~~3u.C[Fx~~E33 <br />CONSULTING GEOTECNNZCAL ENGINEERS AND MATERIALS TESTZn[G <br />San Juan County Commissioners: <br />P.O. Box 466 e/~l e~~`~a <br />Silvenon. Colorado 81433 O• , O ~~ <br />Subject: Eureka Gravel Pit ~io~~`-`v7o~~°! ~oo~ <br />a <br />June 4, 2004 Cursory Site Observations ~~/s <br />Eureka, Colorado ~Ge~ <br />9y <br />Commissioners, ,. <br />PAGE 02 <br />July 7, 2004 <br />PN: D04155GE <br />This letter is in response to our July 6.2004 telephone conversation with Mr. Louie Giroda, San 3uan <br />County,Road Departmrnt and. presents our cursory observations of the Eureka Gravel Pit and the slope <br />areas above the grave( pit. The observations were conducted with Mr. Giroda on June 4, 2004. Vfe <br />'briefly discussed our observations with Mr. Wally Erickson, Colorado Department of Minerals and <br />Geology on June 11,'2004. Our proposal far a geotechnical engineering slope stability analysis is <br />presented separately:. <br />W e understand that no gravel mining at the pit has occurred since 1998. The grave] mining operation <br />included excavation df material along the tce of an extensive talus slope. The natural slope inclination of <br />the [alus sI'opt is estimated [o be about thirty-five (35) to forty (40) degrees. San Juan County Roed 25 <br />' exists midway up the talus slope and provides recreational access to Eureka Gulch. <br />The mining operation has over-steepened 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 head scarp a few <br />hundred feet below County Road 25. The head scarp will most likely continue ics upward progression <br />until eventually it will influence County Road 25. It does not appear that the rate of up-slope progression <br />is rapid. <br />During August of 2003 a severe thunderstorm hit the southwestern Colorado area. We understand that <br />during this event that County Road 25 was covered with a mudslide from above. ?his event apparently <br />.did not significantly influence the eroding slope area above the gravel pit. Based on the historical <br />performance of the slope it does not appear that a catastrophic immediate failure 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 an event would be Significantly different than natural hazards treated on the alpine roadways <br />throughout San Juan County, Colorado, <br />Please co~r laetes~ii,l}(Qu have any questions. or if we may be of additional service <br />P <br />R.O. BOX ]98b e.0. aox 909E 719 Bodo ~I)rive <br />GRAND JUN[IIQN:':'CO ° ~ MONTRGSE, CD 81002 DURANGO, CO. C1]O1 <br />(9]01 295-96OS 1990) 299-2159 190! 2>9-5095 <br />