4320 THOMSON AVE GEOTECHNICAL ENGINEERING REPORT Geotech Report 2023-08-10

GeoTest Services, Inc. 4320 Thomson Avenue, Everett, WA PURPOSE AND SCOPE OF SERVICES March 17, 2022 Project No. 22-0285 The purpose of this evaluation is to establish genera I- subsurface conditions beneath the site from which conclusions and recommendations pertaining to project design can be formulated. Our scope of services includes the following tasks: • Explore soil and groundwater conditions underlying the site by advancing 2 Dynamic Cone Penetrometer (DCP) explorations and 2 exploratory test pits with a client -provided excavator to evaluate subsurface conditions. • Provide a written report containing a description of subsurface conditions and exploration logs. The findings and recommendations in this report pertain to site preparation and earthwork, seismic design, foundation recommendations, concrete slab -on -grade construction, foundation and site drainage, temporary and permanent slopes, geotechnical consultation, and construction monitoring. GeoTest previously prepared a Geohazard Evaluation Report for the subject property dated April 12, 2019 (Project No. 19-0050). As only limited geotechnical recommendations were given in this previous report, the primary purpose of this report is to provide geotechnical recommendations and parameters for use by the design team for this project. PROJECT DESCRIPTION GeoTest understands that the existing residence on the subject property will be removed and replaced with a larger, one-story residence with an attached garage. The new structure will have an approximate footprint of 2,500 square feet. GeoTest anticipates that the proposed residence will be wood -framed and utilize shallow conventional foundations and slab -on -grade floors. As the new residence will be situated near the toe of the existing slope, a soldier -pile shoring wall with shotcrete lagging is planned for the southwest portion of the house excavation. Cast -in - place retaining walls will be constructed to the west of the new residence. Upslope of the residence, a new modular -block gravity wall structure will serve as a catchment wall. GeoTest also understands that stormwater runoff will be conveyed to a detention pipe on the eastern side of the property and then off -site to City of Everett facilities along Thomson Avenue. Thus, an infiltration assessment was not conducted as part of this scope of work. SITE CONDITIONS This section includes a description of the general surface and subsurface conditions observed at the project site during the time of our field investigation. Interpretations of site conditions are based on the results and review of available information, site reconnaissance, subsurface explorations, laboratory testing, and previous experience in the project vicinity. 1