600 RIVERSIDE RD Geotech Report 2022-10-25

Landau Associates 2.3 Surface Conditions The Riverside Business Park is located within the Snohomish River floodplain in North Everett along the west bank of the Snohomish River. The Riverside Business Park is bounded on the west by the BNSF railroad tracks and Delta Yard, a major switching yard. The SR 529 Snohomish River Bridge and BNSF railroad drawbridge bound the project site on the north. To the south, the project site tapers to a point just northwest of the 1-5 Bridge across the Snohomish River. Land use in the vicinity of the project site includes industrial sites situated adjacent to the river, and commercial and residential uses on the hillside to the west. The existing site topography is generally flat -lying with moderate to steep slopes along the northeast edge of the site adjacent to the Snohomish River. Prior to site development activities in 2000 and 2001, site elevations ranged from about elevation 10% to 13%Z ft (NAVD 88). Since the early 2000s, additional fill has been placed across portions of the project site. The upland portion of the project site is vegetated with low growing grasses with scattered saplings, blackberry bushes, and Scots Broom. Other natural site features include two wetland areas that were previously identified by others. One of these wetlands is located along the southwest property boundary and the other wetland area consists of a tidal area adjacent to the Snohomish River in the southeastern portion of the site. On February 27, 2018, a LAI representative using hand tools collected 5 near surface soil samples along the proposed trail alignment at the locations shown on Figure 2. The purpose of collecting the soil samples was to have the samples analyzed by an agricultural testing laboratory. Based on the results of this analysis, the agricultural testing laboratory developed recommendations related to what soil amendments are needed for the plant material proposed along the trail alignment. See Sections 2.4 and 3.9 of this report for additional information related to the agricultural soil testing that was performed. 2.4 Subsurface Soil Conditions Subsurface conditions in the vicinity of the proposed site infrastructure improvements were explored by excavating 5 exploratory test pits (TP-1 through TP-4 and TP-46) on March 9, 2017, and advancing 2 exploratory borings (B-1 and B-2) with a hollow -stem auger on March 14, 2017. The test pits were excavated to depths of about 5 to 9%Z ft bgs. Each boring was advanced to a depth of about 31%2 ft bgs The test pits were advanced along the alignment of proposed trail section E and the two borings were advanced at proposed pump station locations, both along the alignment of 8th Street. The approximate locations of the test pits and borings are shown on the Site and Exploration Plan (Figure 2). A discussion of field exploration procedures, together with edited logs of the test pits and borings, is presented in Appendix A. Geotechnical Engineering Report 0121030.010.011 Riverside Business Park March 22, 2018 Public Access Trails and Roadway Improvements 2-2