1502 WALL ST IMAGINE CHILDRENS MUSEUM Geotech Report 2022-10-25

Imagine Children's Museum Building Addition Revised Geotechnical Engineering Report Everett, Washington Design Recommendations II. DESIGN RECOMMENDATIONS 5.0 INTRODUCTION Our exploration indicates that, from a geotechnical engineering standpoint, the parcel is suitable for the proposed development provided the recommendations contained herein are properly implemented. Native sediments suitable for foundation support were observed at shallow depth in building areas, and conventional shallow and spread-footing foundations may be utilized if they bear directly on suitable native sediments, or on structural fill placed above suitable native sediments. All of the existing sediments onsite are silty and are expected to be highly moisture-sensitive. At the time of our subsurface exploration program, most of the site soils were above optimum moisture content for compaction purposes. Grading with site soils can only be accomplished during the dry summer months when moisture contents can be adjusted by aeration and drying during favorable weather. Significant, but unavoidable effort will be required to dry site soils prior to use in structural fill applications. If the weather conditions or construction schedule make it impossible to dry site soils, most of the site soils will be unsuitable for use in structural fill applications. 6.0 SITE PREPARATION All existing structures, paving, and buried utilities should be removed from beneath planned building areas. Adequate temporary erosion and sedimentation controls (TESCs) should be constructed in accordance with City of Everett requirements. Temporary dewatering equipment should be available and used, as needed, to control groundwater to facilitate construction activities. We do not anticipate that significant quantities of topsoil will be encountered, but topsoil from planter areas and any other topsoil that is encountered should be removed where it occurs below planned structures or paving. Areas where loose surficial soils exist below finished grade due to demolition or stripping operations should be considered as fill to the depth of disturbance and treated as subsequently recommended for structural fill placement. 6.1 Existing Fill We did not observe substantial existing fill in our subsurface explorations; however, the site is developed, and there is some potential that site preparation work will reveal existing fill, especially in the vicinity of the portion of the existing building that will be removed. Existing fill should be removed from the footprint area of the planned addition. If existing fill is March 28,2019;Revised April 16,2019 ASSOCIATED EARTH SCIENCES,INC. SGB/Id-190104E001-3-Projects\201901041KE\WP Pagee8✓