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

ZipperGeo Broadway Everett Expansion Project No. 2601.01 Geoprofessional Consultants July 7, 2022 grading so that an adequate number of density tests may be conducted as structural fill placement occurs. In this way,the adequacy of the earthwork may be evaluated as it proceeds. RECOMMENDED SOIL COMPACTION LEVELS Location Minimum Percent Compaction* All fill below building floor slabs and foundations 95 Upper 2 feet of fill below exterior slabs and 95 pavements Pavement and exterior slab fill below two feet 92 Retaining wall backfill less than 2 feet from wall 90-92 Retaining wall backfill more than 2 feet from wall 95 Upper two feet of utility trench backfill 95 Utility trenches below two feet 92 Landscape areas 90 * ASTM D1557 Modified Proctor Maximum Dry Density Utility Trenching and Backfilling We recommend that utility trenching conform to all applicable federal, state, and local regulations, such as OSHA and WISHA, for open excavations. Trench excavation safety guidelines are presented in WAC Chapter 296-155 and WISHA RCW Chapter 49.17. Utility Subgrade Preparation We recommend that all utility subgrades be firm and unyielding and free of all soils that are loose, disturbed, or pumping. Soils that pump or yield should be removed and replaced. Given the presence of loose to medium dense fill soils across the site,we recommend that the upper foot of utility subgrades be compacted to a firm and unyielding condition.All structural fill used to replace over-excavated soils should be compacted as recommended in the Structural Fill section of this report. Bedding and Initial Backfill We recommend that a minimum of 4 inches of bedding material be placed above and below all utilities or in general accordance with the utility manufacturer's recommendations and local ordinances. We recommend that pipe bedding consist of granular material free from particles greater than 3 inches. All 9