1618 47TH ST SE 2016-01-01 MF Import

I Gcotechnical Lngineering Repori � Singlc-I�amily Rcsidcncc Bvcrett, Washington DecemUcr 9, ?(Ip5 CG I�ilc N�:,. 3017 � �,.�� .4 � Subsw�facc Coudititlns A brief description of the cunditiun; �ncounicrc�l in „ur cxplui:uiun�ti i, mclu�ic�l brlo�c. f�,r u mur� '� detailed description of the sails encountered, rcview the test pit logs in Pigure-l. � The test pits encountered a surficial layer of topsoil approximately 0.4 to 0.3 fect in dcpth within thc :itc. Belo�v the topsoil, «�e encountered fill matcrial in Test Pits I through 2 do�m to depths of 3.0 to 3.1 feet. The fll material ranged from loose to mcdium dense silty fine sand with gravel, organics, and varying � amounts of charcoal and woud dcbris. Below die ull and topsoil in Test Pits 1 and 2, medium dense to dense, bro«m fine to mcdium sand with varying amounts of gravcl �vas encountered to the depths � explored. 1Ve interpret these soils to Ue advance out�vash. In Hand Pits 1 and Z, we encountered 0.2 fect of topsoil. I3eneath the topsoil, we encountemd brown to dark Urown, medium dense silty fine to medium � sand«�ith organics and iracc era�cl down tu thc depths cxplored. �Vc interpret Ihese soils to be��c�thcrcd advance outwash. ,� Thc DCI'Ts, perfonned bct�accn thc ttvo test pits, indicatc loosc scils to a range of depths that su,rgr;t thc � cxistcnce of fill and topsoil. 'I'he depth of the loose material extends to approxiratcly 5.5 to G.0 feet, �vith mcdium dense material cxtending down ro depths of 8A to 9A feet. Cross-Section A-A', presented as Figure 7, shows thc rcl�lionship hcm'ecn the nCPT li�catimis, Tcst Pits I and 2, thc �:round surtace, �nd �� proUable depth of fill. Hydrologic Condit:ons � Ground ��ater seepage rvas not encow�tered in our tcst pit or hancl pit explorations, nor ��as there any I indic�tion that significant water exists. The undcrlying out�vash is considered n�ell draining. Additional ' studies could be done if it is important to verify thc depth to the eroundwater table. Ilowever, ��e espect iltc i�ruimd �cu�cr i:l,lc [0 1�� iccper Ihnn our cxplur:uions. Cf?OLOGIC IiA"I.:�RllS Landslide }Tazard The core of the slope is infcrred to be comprised of the ad��ance out�vash deposits. PJe consider thcse Isoils to be of moderate to high strength and they am considered to bc stable with regard to deep-scated slopc failurcs. There is a potential Qmt the surficial soils on the steeper sections of the slope could slough � o�cr time. Flo�vecer, �ee did not obsen�e any activc cvidcnce of sloughing �ti ithin the soils, and some oF 1 Cornerstone Geotechnical, Inc. �l�