2600 FEDERAL AVE 2021 PORT OF EVERETT 2025-09-29

Substantive Requirements Review Landau Associates 2.0 SITE CONDITIONS The following sections describe the geologic setting of the site and the surrounding area and the subsurface conditions reported by others and observed during LAI's supplemental field investigation. Interpretations of site conditions are based on LAI's review of available geologic and geotechnical information and on the results of its site reconnaissance, subsurface explorations, and laboratory testing. 2.1 Review of Existing Data To develop preliminary design recommendations, LAI reviewed available geologic maps as well as geotechnical and environmental data gathered by others during previous site investigations (Chase T. Main, Inc. 1952; Dames and Moore 1990, 1993, 1995; Aspect Consulting 2013; Shannon &Wilson 2014). The approximate locations of previous geotechnical and environmental explorations are presented on Figure 2. 2.1.1 Geologic Setting Geologic information for the site and the surrounding area was obtained from the Preliminary Surficial Geologic Map of the Mukilteo and Everett Quadrangles, Snohomish County, Washington (Smith 1976). Surficial soil in the vicinity of the site is mapped as modified land. Based on the site history, this soil unit likely consists of non-engineered fill deposited during previous site development, which dates to the late 1800s. The non-engineered fill consists of interbedded sands and silts mixed with wood, concrete rubble, and other construction debris. 2.1.2 Subsurface Conditions Based on LAI's review of available geologic data, site subsurface conditions can be characterized as hydraulic fill placed during previous site development. The hydraulic fill has been described by others as consisting of very loose to medium dense sands and very soft to stiff silts with variable amounts of gravel and organics. The hydraulic fill in the northern half of the site has a high organic content, with areas that include up to 30 feet (ft) of pure wood waste. The heat map on Figure 3 represents the relative severity of wood waste deposits, based on LAI's aggregation of new and existing subsurface data.The relative wood waste ratings were developed in accordance with the following settlement factors: thickness of the wood waste deposit, concentration of wood waste (expressed as a percentage), depth to top of wood waste, and location of wood waste in regard to the groundwater table. The wood waste concentration is based on LAI's interpretation of the soil descriptions presented on historical borings logs. LAI's data review did not include organic matter content of site soils; as a result, the wood waste ratings on Figure 3 may be conservative in some areas and less conservative in others. Geotechnical Engineering Report 0121049.040.041 Norton Terminal Development&MTCA 3rd Interim Action 2-1 May 7,2021