2320 CALIFORNIA ST Geotech Report 2025-07-25

Administration Building Office Expansion Everett,Washington 1 INTRODUCTION This report contains the results of our geotechnical engineering services for use in the design and construction of the proposed Administration Building Office Expansion project located at the Snohomish County PUD No. 1 Operations Center in Everett, Washington. The project location is shown on the Vicinity Map, Figure 1. The layout of the proposed building addition is shown relative to surrounding physical features on the Site Plan, Figure 2. Project Description We understand that the project includes a 32,000 square foot 2-story addition to the southwest side of the existing Administration Building. The upper level of the addition will be occupied with the new Energy Control Center and will contain sensitive power and computer systems. The project also includes additional surface parking and an expansion of the stormwater pond that will be built as part of the Pole Storage Addition project. The location of the proposed surface parking area has not been finalized at this time. Possible locations for the parking addition include northwest of the current Administration Building, west along the entrance road,or north of the helicopter pad. Purpose and Scope The purpose of our services is to explore the subsurface conditions at the site as a basis for providing geotechnical recommendations for design and construction of the proposed Administration Building Office Expansion project. Our geotechnical engineering services were completed in accordance with our proposal ' for the project,dated September 14,2009 and our on-call agreement with Snohomish County PUD No. 1. FIELD EXPLORATION AND LABORATORY TESTING Field Explorations The subsurface conditions for the proposed building addition were evaluated by excavating five test pits(TP-1 through TP-5)to depths of 5 to 51/2 feet below the existing site grade. The approximate location of the test pits are shown on the Site Plan, Figure 2. A detailed description of the field exploration program is presented in Appendix A. Previous Studies ' We reviewed previous geotechnical studies that were completed as part of the Pole Storage Addition project and a previous addition to the Administration Building. The approximate locations of the previous borings (B-2 and B-3) and test pits (TP-1 and TP-5) are shown on the Site Plan, Figure 2. The exploration logs are r included in Appendix C. Laboratory Testing Soil samples were collected from the test pits, taken to our laboratory and examined to confirm or modify field classifications, as well as to evaluate engineering properties of the soil. Representative samples were selected for laboratory testing consisting of determination of moisture content and grain size distribution. A description of the laboratory testing and the test results are presented in Appendix B. 1 GEOENGINEERS October30,2009 ! Page 1 File No.0482-031-02