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ciLy <br />Ur tuyene Uontract #eulu-uueob txnlblt <br />b: <br />Scope of WorK <br />C <br />mi <br />Qo <br />ia <br />- <br />May 10, 2010 <br />Mr. Terry Colvin <br />Public Works, Engineering <br />City of Eugene <br />via eraaail: t rru.r.colvi€tt ci.eu.ccne.or.us <br />RE: PROPOSAL, SLOPE STABILITY ASSESSMENT, 549/551 MONTAR.A WAS' SEWER <br />Dear Intr. Colvin: <br />Per our recent discussions, I am submitting the following proposal to conduct an assessment of soils <br />eondifions and slope stability along the sanitary/storm sewer alignment in the vicinity of 549 and 551 <br />Montara Way. The storm server outfall into the draw below these addresses has recently (last wet <br />season) eroded significant amounts of material previously covering the concrete pipe and several <br />concrete pipe sesiments have failed into the draw below. Theoutfall has now, been temporarily fixed <br />using, a plastic culvert pipe. However, vidco reports from the storm pipe indicate that the pilae lasts <br />been separated along nunICI-aus joints in this Vicinity, apparently mostly its the steeper sections <br />directly the houses and above; the lower leg of Wawa Way. These separations may contribute <br />water to the subsurface during high flows, or may result its more effective de-watering of (lie <br />subsurface during, low flows, or both. <br />Based on the observations at the site to date, below the houses, the ston-n sewer has been placed: into <br />a pre-existing, swate and. was then covered by mote than 10 feet of fill, probably locally derived <br />during grading for the subdivision. Based on assessments conducted by GeoScience in the vicinity <br />previously, the fill probably consists of a mixture o clayey soil, igneous rock fragments, and, <br />passibly, decomposed s dstonel'siltstone, Its-pi pock; in the vicinity of the two houses consists <br />of decomposed sandstone. <br />Based on GeoScience°s observations said experience at the slope movement below 565 Montara <br />Way, subsurface exploration through the fill % ill be diff ictilt dare to very difficult equipment access <br />d the presence oflargerac fragments. Aowevet in order to determine mitigation opt oias'for the <br />sewer pipe(s) and outfall it is imperative that the snail conditions in this vicinity are well defined. <br />10itiitfljt= it is proposed Cca crarrcluct a sc ie4v l tl c c< ttstruc ion arid TV records for the sever pipes <br />it) detemtine exact locatiorts ofthe pulled-apari joitats. Detailed, field-des=eloped cross sections will <br />fie measured along the sewer pipe alig. onle€tt. t tsiiSg these crass. sections; as best possible, the <br />alTotecl " inns will be niarlC4pd rata the ground ttC:oiig, the alignment and € n the cross sections. <br />Appropriate subsurface exploration points will ti c;i be determined and lwnd4uger borings and <br />Williamson Relative Density Drive Probes irtstafted to determine subsur ace soil characteri;stics, <br />v t cal and lateral dtstr:.i trtiort of soil/fill unitss, and relative wil strengths, <br />P.O. Box 2~ , Sugene, OR 97402 (541)'.W5700 FAX; 607-6,:701 Gil 127073 <br />