215 DORN AVE Geotech Report 2022-10-25

Geotechnical Engineering Evaluation Multi-Family Residential Development 215 Dorn Avenue Everett, Washington INTRODUCTION This report presents the results of our geotechnical engineering investigation and evaluation of the planned Multi-Family Residential Development project in Everett, Washington. The project site is located at 215 Dorn Avenue, as shown on the Vicinity Map in Figure 1. The purpose of this study is to explore and characterize the site's surface and subsurface conditions and to provide geotechnical recommendations for the planned site development. The site consists of a rectangular parcel covering approximately 0.3 acres. The site topography is composed of relatively level to gently sloping ground. Currently, the property is vacant, besides a detached shed structure on the southeastern property line. We understand that the proposed development plan includes construction of two new duplex structures on the northwestern portion of the property, accessed by driveway areas along the southeast portion. We also understand that stormwater generated within the property may be directed to onsite infiltrations systems, if feasible. The existing site layout is shown on the Site Plan in Figure 2. For our use in preparing this report,we were provided with a preliminary plan set titled"EFI Properties LLC—Proposed 2 Duplex Project," including site, drainage, sewer and water, grading, and TESC plans, dated February 21,2018 and prepared by Donna Breske&Associates,LLC. SCOPE The purpose of this study is to explore and characterize the site surface and subsurface conditions, and provide general recommendations for site development. Specifically, our scope of services included the following: 1. A review of available soil and geologic maps of the area. 2. Exploring the subsurface soil and groundwater conditions within the site with trackhoe- excavated test pits. Trackhoe was subcontracted by NGA. 3. Performing grain-size sieve analysis on selected soil samples, if necessary. 4. Determining feasibility of stormwater infiltration within the site. 5. Providing long-term design infiltration rates based on on-site Small Pilot Infiltration Testing(PIT)per the 2014 SWMMWW,if necessary.Water to be provided by the client. 6. Providing recommendations for earthwork and foundation support. 7. Providing recommendations for temporary and permanent slopes NELSON GEOTECHNICAL ASSOCIATES, INC. 84