9900 19TH AVE SE Geotech Report 2018-01-02 MF Import

Geotechnical Engineering Report 1 Home Base Warehouse - Everett July 31, 1997 NCA File No. 213497 Page 3 SITE CONDMONS Surface Conditions The lot is approximately 10 acres in size, has a rectangular shape, and is currently undeveloped. The site is bordered on the north by a roller-skating rink, on the east by 19th Avenue FE, on the south by I00th Strtet SE, and on the west by the Interstate 5 right-of-way. The east side of the site is generally level. The west side of the site slopes approximately 23 to 29 percent down into a ravine with a low wetland area that crosses the site in a north -to -south direction. The total vertical relief of the property is approximately 46 feet. The east side of the site has been cleared in the pact and is covered with brush, blackberry bushes, tree stumps, and field grass. The west side of the site is vegetated with evergreen and deciduous trees and underbrush. Surface water was observed in the wetland on the west side of the site. We observed approximately 6 inches of water where we hand probed in the wetland. Geology Most of the Puget Sound region was affected by past intrusion of contirental glaciation. The last period of glaciation, the Vashon Stade, ended approximately 10,000 to 11,000 years ago. Many of the physical features seen today are a result of scouring and overriding by glacial i ;e. During the Vashon Stade, the Puget Sound region was overridden by over 3,000 feet of ice. Soil layers overridden by the ice sheet were compacted to a much greater extept than those that were not. A typical glacial sequence includes glacial till overlying advance outwash sand. The geologic units mapped for this area are shown on the Geologic Mau of the Everett 7.5-Minute Quadrangle, Snohomish County. Washington, by James P. Minard (U.S.G.S., 1985). The site vicinity is mapped as glacial till (Qvt) and advance outwash (Qva). The gla-:ial till consists of a dense, non -sorted mixture of clay, silt, sand, and gravel. The advance outwash deposits consist of stratified sands and gravels. Our explorations encountered glacial till and advance ortwash. Subsurface Conditions Subsurface conditions were explored at the site on July 2 and 3, 1997 by excavating eighteen test pits with a trackhoe and by hand probing areas in and around the wetland that were inaccessibi.- to the trackhoe. 1'he site was explored to depths of 6 to 12.6 feet below the surface. The test pits were not deep NELSON-COUVRETTE & ASSOCIATES, INC.