3400 RIVERFRONT BLVD Geotech Report 2022-10-25

• • • • 1.0 INTRODUCTION • This report presents the results of our geotechnical engineering evaluation for the Everett Riverfront Eclipse Site project that will be located between 3300 and 3600 Chestnut Street in • Everett, Washington. We understand that Polygon Northwest Company(Polygon) is proposing to • develop the site with approximately 190 townhomes. The proposed townhomes will typically be three stories in height and will not have basements. New roads and utilities will also be 41 constructed for this project that will eventually be owned and maintained by the City of Everett (City). The site is approximately 16 acres in size and is located along the west bank of the • Snohomish River and east of a Burlington Northern Santa Fe railroad line. The site location 411 relative to surrounding physical features is shown on Figure 1. • In the spring of 2015, GeoDesign was asked to evaluate the potential for static settlement to • occur at the site. Based on our review and analysis of the existing subsurface information, we • recommended that a surcharge be placed on part of the site to accelerate the consolidation of • subsurface soil. After issuing our recommendations, we performed additional explorations to evaluate the stability of the slope near the Snohomish River. We were also provided copies of • additional geotechnical reports that were previously prepared for the site. This report includes • an updated summary of our settlement analysis to justify our recommendation for a surcharge. This report also includes information to address seismic hazards and other concerns identified by the City. Acronyms used herein are defined at the end of this document. All elevations in this report are • based on NAVD88. • 2.0 PROJECT BACKGROUND • • The site is located along the western bank of the Snohomish River and was previously occupied • by the Eclipse Lumber Company. The original mill and lumber yard were destroyed by a fire in • 1962. The site continued to be used as a log sorting yard until it was acquired by the City in 2004. The existing Eclipse Mill Road (also called Chestnut Street and Riverfront Drive)traverses • the middle of the property in a north-south direction. This road was routinely subject to heavy • logging truck and equipment loads. There are existing City utility lines beneath Eclipse Mill • Road. According to a City Public Works Permit issued in 2002 (Public Works Permit No. PW0210- 027), most of the property west of Eclipse Mill Road was covered with approximately 30 feet of • soil in order to surcharge the site for future development and offset the static settlement • potential of fill that was placed over the last 100 years. Additional stockpiles of construction materials and logs were also stored on the property over the years. A railroad line was previously • located east of Eclipse Mill Road that was later abandoned. • Grades at the site were previously raised for various stages of development. Floods from the Snohomish River periodically inundated the site before grades were raised. At the time this • report was written, Polygon had finished placing additional fill at the site to raise final grades • above flood elevations. According to grading plans prepared for this project by Core Design, Inc. dated March 2015, the proposed final grades will generally be between elevations 20 and • 24 feet. 110 G EO DESIGN= 1 Polygon-128-01:09161 5