2320 RAILWAY AVE INTERWEST CONSTRUCTION INC Geotech Report 2023-02-17

Interwest Construction Co.-Railway Avenue Improvements, Everett,WA Feb. 14,2019/Revised Feb. 7,2020 Geotechnical Engineering Report P1486-T18 1 Improvement plans for this project include a paved extension of Railway Avenue to access the parcels to the north, as well as a 12-inch water line and a 54-inch storm line. 2.0 EXPLORATORY METHODS We explored surface and subsurface conditions at the project site from December 12 to 13, 2018. Our exploration and evaluation program comprised the following elements: • Surface reconnaissance of the site; • Six auger boring explorations(designated B-1 through B-6),advanced on December 12 and December 13, 2018; and • A review of published geologic and seismologic maps and literature. Table 1 summarizes the approximate functional locations and termination depths of our subsurface explorations, and Figure 2 depicts their approximate relative locations. The following sections describe the procedures used for excavation of the borings. TABLE 1 APPROXIMATE LOCATIONS AND DEPTHS OF EXPLORATIONS ' Termination Exploration Functional Location Depth (feet) B-1 ±10 ft north of entrance gate to Penske parcel,at edge of gravel drive 111/2 B-2 ±400 ft north of B-1,near north end of Penske parcel,at edge of gravel drive 11 B-3 ±400 ft northwest of B-2,near drainage ditch east of line of shipping containers 111/2 B-4 ±400 ft northwest of B-3,in marshy area north of shipping containers 111/2 B-5 ±400 ft northwest of B-4,south of area with numerous rubble piles 111 B-6 ±400 ft northwest of B-5,near northern intersection of river and railroad line 111/2 ' The specific numbers and locations of our explorations were selected in relation to the existing site features, under the constraints of surface access, underground utility conflicts, and budget ' considerations. It should be realized that the explorations performed and utilized for this evaluation reveal subsurface conditions only at discrete locations across the project site and that actual conditions in other areas could vary. Furthermore, the nature and extent of any such variations would not become evident until additional explorations are performed or until construction activities have begun. If significant variations are observed at that time, we may need to modify our conclusions and recommendations contained in this report to reflect the actual site conditions. 2_1 Auger Boring Procedures Our exploratory borings were advanced through the soil with a hollow-stem auger,using a track- mounted drill rig,operated by an independent drilling firm working under subcontract to MGI. An engineering geologist from our firm continuously observed the borings, logged the subsurface conditions, and collected representative soil samples. All samples were stored in watertight containers and later transported to a laboratory for further visual examination and testing. After the borings were completed, the borehole was backfilled in accordance with state requirements. Migizi Group, Inc. Page 2 of 13