Laserfiche WebLink
Gcotcchnica: Ln�inccring Rcport <br /> i Single-Pamily Rcsidcnce <br /> ( B��cretl, Washin�ton <br /> Decembcr 9, 200� <br /> � CG Filc No. 2017 <br /> Pagc 5 <br /> � the vcgetation on thc slopc is considercd mature. Thc large cedar trec locatcd on thc stecp slope appears <br /> to have minimal bends throughout its height, which may indicate soil creep. Ne observed deciduous trees <br /> � on and around the slope that appcar to bend and lean in all different directions, which could suggest slopc <br /> movement. However, deciduous trccs oftcn gro�v naturally in this manner. Any slough events are <br /> � expected to be surficial, and are affccted by surfacc ��atcr and man made impacts. The risk of slough <br /> events can be minimized if proper drain��gc is installed, vcgetation on the slnpe is maintaincd, and yard <br /> � waste and o;1:cr debris arc kept off the slopes. 1Ve �coul�l e�pcct if a slnueh c��ent �s�ere to uccur, it �could <br /> bc relatively shallu���. ���ithin thc upper> fcct or eo. <br /> � Erosion Haz:ird <br /> The erosion hazurd criteria uscd fbr dctcrminuliun of alTcctcd arcas includcs seil ty�pe, slape gr;idicnt, <br /> � vegetation cover, and ground water conditions. The erosion sensitivity is related to vegetative co�cr an� <br /> thc specific surface soil types (group classification), which are related to the underlying gcologic soil <br /> 1 units. The Soil Survey of Snohomish County Area Washington by the Soil Conscivaiion Servicc (SCSj <br /> � was revicwed to dctermine the crosion hazard of the on-site soils. The site surfacc soils �vcrc classiGed <br /> � using the SCS classitication system as the Aldernood — Urban Land Complex, 8 to 15 percent slopes <br /> i <br /> (Unit 6). The corresponding geologic unit for these soils is till, �vhich is consistent with the till mapped <br /> � ncarb�. The soils encountercd in a�r cxplorations appear to be more akin to Evcrett (Unit 17) or <br /> Indianola (i,'nit 26) soils, bo[h mapped ncarby on the SCS's map. The crosion hazard for the soil is listed <br /> � as being slight lor the gently sloping conditions at the site. 1Ve inte��ret the erosion hazard to bc <br /> modcratc to se�•rrc duc to the existing stcep slope and sandy soils. <br /> I S+eismic }lazard <br /> It is our opinion, b:ised on our subsurfac� c�plorations, thu[ thc Soil Profilc in accordancc ���ith 'I'ablc <br /> 1615.1.1 of the 2003 International Building Code (1BC) is Soil Class D. \Ve re(ercnced the 2002 map <br /> fram the US Gcological Survey (USGS) wcbsite to obtain values for Ss and S�. The USGS �ecbsite <br /> includes thc most updated publishcd data on scismic conditions. The scismic design parameters �re: <br /> St l 18.9246 g <br /> Si 41.86% E <br /> P, IA2 GromTablc1G15.1?(1)ofdu2003II3C <br /> I , ].��i Prom"Iablc 1615.1?(2) ofthe 2003 IBC <br /> Cornerstone Geotechnical, Inc. <br /> U/>�., <br /> L <br />