500 LAUREL DR 2016-01-01 MF Import

Geotechnical Engineering Study 00-2267 Three Story Addition - 500 Laurel Street, Everett January 31, 20U1 Page S � At a depth of about �ixteen (16) feet we then encountered an approximately two foot thick stratum of wet, medium de�se to very dense, silty sand with a little gravel. According to the USCS this materi�l was classified as a SM. Beneath this stratum we then penetra+ed about four feet of hard silt and then about four feet of very dense or hard sandy silt. Both of these sti�ata were classified by the USCS as a ML. Underlying this sandy silt, and extending to the depth explo��ed, we then encountered a hard clayey silt which we classified by the USCS as CL. Local Geology: In an effort to furthersupport our assessment of the in-situ soil conditions we also review�ed the U.S.D.A. Soil Conservation Service soil �:ap ofi Snohomish County for this general site are,� (sheet 35). According to th�s source the site area is generally underlain, at least at shallow depth, by the Alderwood Gravelly Sandy Loam (4 and 5). These generally "non plastic" materials typically include between about ten (10) and forty (40) percent soil fines (silt and clay sized particles passing the nurnber 200 mesh sieve), and up to about ten (10) percent of particle� of greater than three inches in size. They are also typicaily described as being "cemented" at a depth of about three feet. These descriptions are in general accordance rvith the silty sand soils found <st this site. We also reviewed the geological data presented on the Everett Geologic Map (Geoiogic Map of the Everett 7.5-Minute Quadrangle, Snohomish County, Washington by James P. Minard, USGS, MF-1748, 1985) which encompasses the site. According to this map the site area is underlain by the Advance Outwash soils (Qva). These deposits typically comprise clean, well stratified, unconsolidated sand with pebhles and some cobbles and is locally silty. This unit is as much as tw� hundred (200) feet thick. The materials exposed along the ste�per westem bluff slope in this area are described as the Trarasitional Beds (Qtb). These materials typically comprise clay, silt, and fine saniis often containing gravels. This description is also in reasonably close ayreement with the descriptions of the soils developed from the exploratory boring samples and from the observed conditions along the toe of the slope. The local gealogy is piu±ordally depicted on Plate 4 for you information. Soil Behavior: Iri general, the medium dense surficial and shallow "native" silty sand soi! is considered firm, competent and generally unyielding in-place. This � � I I F� � � 1 1 1 � � 1