2410 RAILWAY AVE Geotech Report 2023-04-06

Penske Truck Leasing-Proposed Service Facility,2410 Railway Ave,Everett,WA Mar.8,2019/Rev.Feb. 25,2020 Geotechnical Engineering Report P1493-T18 3.0 SITE CONDITIONS The following sections present our observations, measurements, findings, and interpretations regarding, surface, soil, groundwater, and infiltration conditions. 3.1 Surface Conditions As previously indicated, the project site consists of a historical log and timber storage site for the Kimberly-Clark Corporation. Two roughly parallel gravel driveways line the eastern edge of the project area, connecting where they intersect the fence gate at the southeastern corner of the property, and forming a U-shaped turnaround at the northern end of the property. The northern part of these gravel roads intersects a separate gravel road which mostly follows the northern and eastern property boundaries and leads to a network of roads toward the Canyon Lumber parcel. A paved roadway,partially overgrown and in disrepair,crosses the project site from east to west at an angle, connecting the gravel roadways at either edge of the lot. The project site and the surrounding area is relatively flat, with only minimal elevation change. Vegetation onsite consists mainly of various types of grass, which is tall and unkempt in many portions of the project area. Ornamental trees line the gravel driveway along the easternmost edge of the parcel and small saplings have begun to grow in the central portion of the site. Blackberry bushes and scrub brush are extremely common everywhere except the high-traffic gravel driveways. The project area is located in a bend of the Snohomish River, and some ponding was observed at surface elevations on the site. No other hydrologic features were observed onsite such as seeps or springs. 3.2 Soil Conditions We performed fourteen auger boring explorations as part of this geotechnical study;one near the proposed underground fuel storage tanks to a depth of 25 feet; six within the footprint of the proposed service bays and office space to depths of 71/2, 15, and 50 feet; and seven spread evenly across the remainder of the site to depths of 10 feet. Our subsurface explorations encountered relatively consistent subgrade conditions across most of the project area, consisting of a surface mantle of thick vegetative groundcover and a dense layer of gravel or quarry spalls within two to three feet of surface elevation. Below this horizon is interbedded alluvial sand and silt with abundant organics, which were observed at depths up to 50 feet. The organics encountered were typically wood chips or"hog fuel",often seen as thin beds within sandy or silty units. Occasionally, very thick pieces of timber were encountered at depth,possibly indicating buried logs or branches. All subsurface explorations except boreholes B-7,B-9,B-13,and B-14 encountered very similar units of brown/grey silt at depths between 5 and 25 feet. This silt unit forms beds ranging in thickness from 6 inches to several feet and is often interbedded with dark gray fine to coarse sand that was observed in all of our subsurface explorations. Boring B-13 was terminated at 71/2 feet due to a strong gasoline odor in the cuttings. Borings B-12 and B-14 encountered fine to coarse sands with trace silt,gravel and organics at depths below 20 to 25 feet. All sands below 35 feet in both of these deeper borings had blow counts between 22 and 43, indicating medium-dense to dense bearing Migizi Group, Inc. Page 4 of 17 r.u�i t �lil�