4703 GLENHAVEN DR 2016-01-01 MF Import

IPrcliminary Gco�cchnical Lcucr Landslidc Evaluation and Rcpair 1 4703 Glenhaven Drivc Hvcrett,Washington Fcbn�ary I, 2007 I NGA Filc No. 75570G Pag�s gravel,cobbles, and boulders depositecl by the icc shect. 1'he advance ouhvash is described as clean sand Iwith gravcl and cobblcs dcpositcd by mclt watcr strcanu in front of thc advancing glacicr. Our cxplorations en:ounter�d ,ilt ani, .;ilty s.md ,rt depth gcner.dly consistent with ihe d_scription of glaci:d I ull. � tixplorations: Thc subsurface conditions within the sitc wcrc explored on Decembcr 21, 22, and 27, 200G, and January 17 and 13, 2007 by drilling cleven gcoteclmic:�l borings to depths ranging from 7.8 to I2�.5 fect bclow thc cristing gmund surface using a limited �ccess drill rig. The approximatc location, of our cxplorations arc shown on thc. .c Plan in Figurc 2. IA dl'OIObISI ��OIII �<JA �vas pracnt during thc cxplorations, csamincd thc soils and geologic conditions Icncountcrcd, obtained samplcs of thc different soil typcs, and nu�iNained logs of the csplorations. A Standard Pcnctration Test (SPT) was performed on cach of ihe s:unples during drilling to docwnent soil ( density at depth. Thc SI'T consists of driving a two-inch outervdiameter, split-spoon sampler I S inches � using a 140-pound hammer with a drop of 30 inchcs. The number of blows required to drive the samplcr I thc final 12 inches is refcrred to as the "N" valuc and is prescntcd on thc boring logs. Thc N valuc is used to cvaluatc the slrcngth and density of thc dcposit. I1'he soila �verc ��isually classificd in general accordancc with the Unificd Soil Classification Systcm. presented ,n Pioure G. Thc logs of our borings aro auached to this Ietter and are presented as Figures 7 throueh 17. �Vc prescnt a bric(summary of thc subsurfacc conditions in �hc following paragraphs. For a � � dctailcd dcscription of tlic suU�urt;icc conditiuns, thc horin��o�s should bc revictved. � i � Borings I throu��h G, and S. 9. I I, and 12 were drilled within the slope anrl (:iiled arw of the site. At thc surface of Qorings 4, 5, and 9, we encountercd approsimately two feet of topsoil, and at the surface of Borin, I I, we encotmtercd approximarely one foot of bark mulch. Delow the topsoil and mulch in t3orings 4, 5, 9, and I I, and from the surface of Borings I, 2, 3, 6, and S, we encountcred appro�imately 4.0 to 10.0 fc.;t of bro�vn-gray, vcry soft, soft, :md nudium stiff silUclay with varying amounts of finc s,md. \Vc interprcteJ this materi:�l to bc lill. 13e1o�� the fill. ��e gencrally encountered bro�vn to gray silt ( NELSON GEOTECHN/CAL ASSOCIATES, lNC. � , I