7000 HARDESON RD Geotech Report 2022-10-25

INTRODUCTION This report presents the results of our geotechnical engineering investigation at your proposed pavement renovation and replacement project, in the Everett area of Snohomish County, Washington. The site is located at 7100 Hardeson Road, as shown on the Vicinity Map in Figure 1. You have requested that we complete this report to evaluate subsurface conditions and provide recommendations for site development. We have previously completed a Groundwater Investigation memo dated January 25, 2018. For our use in preparing this report, we have been provided with plan sheets PVA04, TS03, SD11 and SDD04 by KPFF dated February 14, 2018. We have also been provided with stormwater plan review comments by the City of Everett dated February 9, 2018, PROJECT DESCRIPTION The project will consist of renovation and replacement of selected areas of asphalt pavement. An underdrain trench system consisting of 4-inch diameter PVC pipe surrounded in gravel and geotextile will be integrated into the storm drain system. SCOPE The purpose of this study is to explore and characterize the subsurface conditions and present recommendations for site development. Specifically, our scope of services as outlined in our Services Agreement, dated July 3, 2017, includes the following: • Mark the site in white paint for utility locates. • Subcontract a private utility locating company to video the drain lines around the building. • Explore the subsurface conditions at the site with borings. • Install standpipe piezometers in selected borings and pressure transducers in each standpipe. • Download and interpret the groundwater elevation data from the pressure transducers on an as-needed basis. • Complete laboratory testing of selected soil samples from the borings. • Complete engineering analysis and provide our observations, conclusions and recommendations in a geotechnical engineering report. SITE CONDITIONS Surface Conditions The site is a former gravel pit and is underlain by about 20 to 30 feet of fill. Access to the site is provided by Hardeson Road to the east. The site is also bordered by a steep slope to the west, and manufacturing to the south and north. A layout of the site is shown on the Site Plan in Figure 2. The ground surface within the site is generally gently sloping down to the northeast. The site is developed with an administrative building and asphalt-covered parking south and east of the building. Merrill Creek is located east of the asphalt covered parking. Four modular buildings and concrete-covered bus parking is located west of the administrative building. Robinson Noble, Inc.