1815 13TH ST SEATTLE CHILDRENS NORTH CLINIC Geotech Report 2022-10-25

• the logs of one boring(B-2)completed by GeoEngineers in 2006 for the Acute Care Tower and Parking Garage project; ■ the logs of three borings(EB-1 through EB-3)completed by Associated Earth Sciences, Inc. in 2003 for the Colby Cancer Center project;and • the logs of one boring (RZ-2) completed by Rittenhouse-Zeman & Associates in 1988 for the Everett General Hospital project. SITE CONDITIONS Surface Conditions The CUP building is located near the center of the site with an asphalt parking lot located to the east of the CUP building.Grass borders the CUP building to the west and extends to the property line to the north.Site grades are relatively flat at the project site and vary between Elevation 115 and 125 feet. Subsurface Conditions GeoEngineers' understanding of the subsurface conditions is based on review of existing geotechnical information in the vicinity of the site.The approximate locations of the previous explorations are shown in the attached Site Plan (Figure 2). The soils encountered at the site consist of asphalt pavement overlying fill and/or glacially consolidated soils. Organic silt deposits were encountered near the ground surface in the vicinity of borings GEI-5 and GEI-9.The materials encountered in the explorations are described below. Fill was observed in several of the borings to depths ranging from 3 to 5 feet below existing site grades. The fill generally consist of very loose to medium density silty sand with variable gravel and organic content. A thin layer of soft,organic material was encountered in boring GEI-9 at a depth of approximate 3 feet below existing site grades. Stiff organic soils were observed in boring GEI-5 at a depth of between 5 and 6 feet below site grades. Glacially consolidated soils were encountered below the fill and organic soils and consists of medium dense to very dense silty sand with variable gravel content and hard silt and clay.The glacially consolidated soils were encountered in the borings at depths ranging from near the ground surface to 5 feet below site grades. The glacially consolidated soils extended to the depths explored. Occasional cobbles and boulders are typical of glacially consolidated soils and may be present at the site and have been encountered in nearby construction projects. Groundwater Conditions The borings completed at the site did not extend deep enough to encounter the regional groundwater table. Perched groundwater was encountered in explorations GEI-2 and GEI-7 at approximate depths of 13 and 19 feet below site grades.Where encountered on adjacent projects, perched water did not require active dewatering and was not a significant factor in shoring or foundation construction. GEOENGINEERS April 22,2016? Page 2 file No.10738-010-01