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, <br /> Gcotechnical l:nginccring G�te��uation <br /> 8310 Rim Drivc- Ryan <br /> Novembcr R, 2004 <br /> RMI Pilc No. "_'1604 <br /> Pace z <br /> Gcologic Conditions <br /> I.andfonns within this region comprise n .rystem of glacially sculplurcd fentures, ���hich hnre been <br /> c�posed b)' post- ncial erosion. Locally, the urr.iin oF this arca hns been glacially modi(icd. The soils <br /> ��cre placed cither prior to, or during the latest glnciation of thc Puge[ Lowlsnd nrea. Glacial ice last <br /> uccupied �hc region during thc late Plcistocene epoch, some 10,000 �0 13,000 years before the present. <br /> 'I�he latcst glacial advance over the nrca is rcfcrrcd tu as the Vashon Stade ofthe Frascr Glacintion. �vhich <br /> deposited thc glacinl malcrials on sitc. <br /> Litcraturc Rcvic�� <br /> Thc Gcologic Map of lhc Surficial Dcpusits in thc Scattic Arca 30-by 60- minute Quadranglc by l'ount ct <br /> nl notes th.�t Ihis nre;i contains adeancc ouh;atih deposits. Qaa, of dense sands and gra��cls. <br /> Sitc Conditions <br /> �Ve obsrned soil c�posures on the site. 1'hese observatimis confirnted lhc esistcnce of advance ouh��ash <br /> soils. <br /> Hydrologic Conditions <br /> Nn �r.uer �cas ohsened an ihc sur(.ue As adc;mcc uut��ash soils are generally oell drained with high <br /> pernuahilitics. no growid��atcr is c�pcctcd to bc cncountcrcd �cithin many fcet ofthc ground surfacc. <br /> Slopc Stabilitc <br /> 'llic curc of �hc lot cumpnscs glnciall}' compactcd dcposits �f compact nchancc oui��'ash sands and <br /> gravels�cobbics. We did not ohservc signs of dccp-scalcd slopc failures and ��ould not c�pcct any. Thcre <br /> ��� .� ,o ai�i..of instahility on neiehborin�+propertics. <br /> It is our opinion that there is not n significmit potential liir deep-sented slope instnbilit}. <br /> tii��ns of back�vasting (mn��ement of ncar-surfacc soil) througli esposed soii erosion processcs or local <br /> surt:uc slides are common to steep slopes, particularl� where esposcd to ���eathering, such as rnin, wind, <br /> ;md Ircczo-iha��'. l hrrc ��cre no perc ,ptihlc tiitns ol signilicant backwastinc. <br /> RMI Associates, Ltd. <br />