902 PINE ST NORTH SOUND BEHAVIORAL HEALTH TREATMENT CENTER Geotech Report 2022-10-25

GeoTest Services, Inc. November 16,2018 North Puget Sound Behavioral Health—Treatment Center Addition Job No. 18-0770 The existing parking area where our explorations occurred slopes gently downward from the northeast corner of the property to the southwest corner of the property. Within the area of planned improvements, the elevation ranges from approximately 100 feet to 90 feet. Minor to moderate cut and fill grading is expected to achieve desired finished grades. SITE CONDITIONS This section discusses the general surface and subsurface conditions observed at the project site at the time of our field investigation. Interpretations of the site conditions are based on the results of our review of available information, site reconnaissance, subsurface explorations, laboratory testing, and our experience in the project vicinity. Surface Conditions 1 The subject parcel is approximately square in shape. Native trees and vegetation have been removed from the site, and existing vegetation consists of trees, bushes, shrubs, and grass within designated landscape areas. One large, multiple story structure is located within the center of the lot. Two smaller structures are located to the west side of the site. The remainder of the site is largely occupied by hardscape parking lots, drive paths, and walkways. The surrounding areas are generally developed with residential, commercial, and academic facilities. No surface water was observed at or in the vicinity of the site at the time of our investigation. The proposed development will be located immediately east of the northern-most portion of the existing building occupying the site. The area where the addition is planned was occupied by asphalt parking and landscaped tracts at the time our investigation. Subsurface Soil Conditions Subsurface conditions were explored by advancing four hollow-stem auger exploratory borings(B-1 through B-4)on October 18, 2018. The explorations were advanced to depths of between 11.5 feet and 41.5 feet below ground surface (BGS) using a subcontracted drill rig. The on-site subsurface soils generally consisted of glacial till composed of very dense, gravelly sand with low fines content to the full depth of the exploration. Photos 1 and 2 on the following page show the subcontracted drill rig at the location of boring B-3 and a hollow-stem auger split spoon sample containing native till material. GTS observed less than 1 foot of crushed surfacing gravel fill directly underlying the asphalt parking areas and approximately 1 foot of landscape bark and topsoil overlying the glacial till within the landscape tracts at the time of our investigation. At the B-4 boring location, approximately four feet of clayey fill was observed below about one foot of landscape bark surfacing before encountering native soil. See the attached Site and Exploration Map (Figure 2) and the Boring Logs (Figures 5 through 8) and Grain Size Analysis (Figures 9 and 10)for more information regarding the approximate locations of the exploration borings and subsurface soil conditions encountered. 1 Page 2 of 17 '