8407 BROADWAY SECURE SPACE STORAGE Geotech Report 2025-04-24

Z i ppe rG eo Broadway Everett Expansion Geoprofessional Consultants Project No. 2601.01 July 7, 2022 Site Preparation Site preparation should commence with installation of TESC measures in accordance with the project TESC Plan.Once TESC measures are installed,we expect site preparation to continue with demolition of existing improvements,clearing and grubbing,stripping,and subgrade preparation.Our recommendations for site preparation are provided below. Clearing, Stripping, Demolition, & Removal of Existing Underground Utilities Once TESC measures are installed, we expect site preparation to continue with stripping existing pavement and demolishing existing structures such as lampposts.We recommend all elements of existing structures on the site be demolished and wasted off site. All clearing and stripping debris should be wasted off site or, if approved, used for topsoil in landscape areas. We recommend that all underground utilities within the proposed building pad be completely removed. Utility pipes outside the building envelope could be abandoned in place, provided they are fully grouted with controlled density fill (CDF) and the trench backfill is density tested or otherwise observed to verify that it meets the compaction levels presented in the project specifications. Localized excavations made for removal of utilities or existing unsuitable trench backfill should be backfilled with structural fill as outlined in the Structural Fill section of this report. Subgrade Preparation Once site preparation is complete, all areas that are at design subgrade elevation or areas that will receive new structural fill should be moisture conditioned to a moisture content within plus or minus two percent of optimum moisture content for compaction. The subgrade should then be compacted to a firm and unyielding condition. Once compacted,subgrades should be evaluated through density testing and proof rolling with a loaded dump truck or heavy rubber-tired construction equipment to assess the subgrade adequacy and to detect soft and/or yielding soils. Construction Drainage Control Stripping, excavation,grading, and subgrade preparation should be performed in a manner and sequence that will provide drainage at all times and provide proper control of erosion. The site should be graded to prevent water from ponding in construction areas and/or flowing into and/or over excavations and existing site steep slopes. Exposed grades should be crowned, sloped,and smooth-drum rolled at the end of each day to facilitate drainage if inclement weather is forecasted.Accumulated water must be removed from subgrades and work areas immediately and prior to performing further work in the area. Equipment access may be limited, and the amount of soil rendered unfit for use as structural fill may be greatly increased if drainage efforts are not accomplished in a timely manner. Weather Considerations If possible, we recommend that earthwork be completed during drier periods of the year when the soil moisture content can be controlled by aeration and drying. If earthwork or construction activities take 6