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IGcotechnical L'nginccring Gvaluation <br /> 16'_� Gngland A��enuc <br /> I L-vcrctt, �Vashington <br /> NGA Pik No. 781 G08 <br /> Pebruary 20,2008 <br /> Pagc 3 <br /> IIn liand Augcr c�plorations I ancl 2, wc encountcrcd medium densc to densc sand �vitl� trace mnounts of <br /> I gravcl and silt to a depth of about cight fcet bclow csisting gradc. Wc intcrprcted thc sand �o bc nativc <br /> glacial advance ouhvash. <br /> IHy�drologic Conditions <br /> GrounJ�vatcr scepagc was not cncountcrcd in any of thc hand augcr esplorations. Thc soils at dcpth wcrc <br /> Igcncrally mois�. Wc anticipatc that perched watcr conditions could devclop during extcnded periods of <br /> rainfall or snowmclt. Perclied �vatcr occurs when surfacc water infiltratcs through Icss densc, more <br /> Ipermcablc soils and accumulates on top oP Icss pcnneablc soil layers or bedrock. Perchcd �vater docs not <br /> represcnt a rcgionnl ground�vatcr "tablc" within thc upper soil horizons. Pcrcl�cd �vater tends to vary <br /> Ispatially and is typically dependent upon thc amount of rainfall. �Ve c�pect thc amount of perchcd watcr <br /> to dccrcasc during dricr timcs of thc ycar and incrcasc during wettcr periods. <br /> IGEOLOGIC HAZARD F,VALUATION <br /> I Erosion liar.ard <br /> Thc critcria uscd for dctcrmining thc crosion hazard for sitc soils includcs soil typc, slopc grndicnt, <br /> vegctation cover, and ground�vater conditions. Thc erosion sensitiviry is related to vegetative cover and <br /> Ia,� s����r� s���r��� so�i �Yn�S, wliich arc rclatcd to thc undcrlying gcologic soil units. Thc Soil Survcv of <br /> Snohomish Arca, Washington, by thc Soil Conscrvation Scrvicc (SCS) was revicwcd io dctcnninc thc <br /> crosion hazard of thc on-sitc soils. Thc sitc aren soils arc mappcd as Indianola Lomny Sand, I S to 25 <br /> percent slopes. TI :crosion hazard for these soils is Jcscribed as slight. The site slopes are considered to <br /> havc a high hazard for watcr crosion in disturbcd areas. Areas wlmrc vcgctation is not disturbcd should <br /> havc a low to modcntc haz�rd for crosion. <br /> I Landslidc Ilazard/Slopc Stabilit�� <br /> j "I'hc critcria uscd for thc cvaluation of landslidc har.ards includc soil typc, slopc gndicnt,and groundwatcr <br /> conditions. The property includcs a gnded pad ancl nortli facing slope with an inclinn[ion of <br /> .�pproximatcly 35 dcgrces (70 perccnt). �Ve did not observc significant crosion or cvidence of dccp- <br /> scatcd landsliciing on thc slopc. \Vc did no[ obscrvc ground�vatcr scepngc on thc slopc at thc timc of our <br /> VISII. <br /> NELSON GEOTECHN/CAL ASSOC/ATES, /NC. � <br /> I ,�N <br />