5900 36TH AVE W PRE APP 015 - 032 - SOUNDVIEW BUSINESS CAMPUS - VERITAS Geotech Report 2025-04-22

Veritas Construction Inc ES-4011.03 June 17, 2016 Page 3 Revised June 22, 2016 Subsurface An ESNW representative was onsite July 31, 2015 and April 18 and 19, 2016 to observe, log, and sample soils at seven test pit locations and five boring locations advanced at accessible areas of the site. The borings and test pits were advanced to a maximum exploration depth of 51.5 feet below existing grades. Soil samples collected at the boring locations were evaluated in the field and laboratory for the purposes of characterizing and classifying the site soils. Please refer to the boring and test pit logs provided in Appendix A and laboratory sieve analysis in Appendix B for a more detailed description of the subsurface conditions. Additional subsurface data was provided in the referenced geotechnical report prepared by Associated Earth Sciences, Inc. (AESI) and are provided in Appendix A. The subsurface explorations were conducted by Hart-Crowser in December 1988 and AESI in March 2000. The approximate boring and test pit locations for all test sites are illustrated on the Boring and Test Pit Location Plan (Plate 2). Topsoil Topsoil was encountered generally within the upper 4 to 14 inches below existing grades at the rtest pit locations. The topsoil was characterized by dark brown color, the presence of fine organic material, and small root intrusions. Based on our field observations, we estimate topsoil will be encountered with an average thickness of 10 to 12 inches across the site, deeper pockets of topsoil, however, may be locally present. Topsoil is considered unsuitable for direct foundation support, or for use as structural fill. However, the topsoil is suitable for use in landscaping areas, if desired. During the initial stages of site work, the geotechnical engineer should discuss the required level of stripping with the owner and contractor based on final grading plans. Overstripping of the site is unnecessary and should be avoided. Native Soils The native soils encountered at the boring and test pit locations consisted primarily of medium dense to very dense silty sand with variable gravel content (USCS: SM) and dense to very dense sandy silts (ML). Poorly graded sand with silt (SP-SM) was encountered at one boring location (B-2) at a depth of approximately 50 feet below existing grades. Native soils reported in the referenced AESI report consisted primarily of medium dense to very dense sandy silts and silty sands with variable gravel contents which is consistent with soils encountered at ESNW test pit and boring locations. Geologic Setting The referenced geologic map resource identifies Vashon glacial till (Qvt) across the majority of the subject site and surrounding areas. As reported on the geologic map resource, glacial till typically consists of a nonsorted mixture of variable amounts of clay, silt, sand, pebbles, cobbles, and boulders, and is commonly referred to as "hardpan". Throughout the descending 111 sloped areas to the north and west, Advance outwash (Qva) is identified with localized exposures of undivided till (Qtu). Earth Solutions NW, LLC