6202 ASSOCIATED BLVD Geotech Report 2022-10-25

Z• Proposed Everett Warehouse ipperGeo Project No. 2152.01 March 5, 2019 present during 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 pavements 95 Pavement fill below 2 feet 92 Retaining wall backfill less 3 feet from back of wall face 92** Upper 2 feet of utility trench backfill 95 Utility trenches below 2 feet 92 Landscape Areas 90 * ASTM D1557 Modified Proctor Maximum Dry Density **Care must be taken not to over -compact retaining wall backfill as over -compaction can induce stresses in excess of design stresses. Moisture Content: Structural fill should be placed at a moisture content within plus or minus two percent of optimum moisture content as determined by the ASTM D-1557 test method (modified proctor). Imported structural fill should be delivered to the site at the recommended moisture content for compaction. Structural fill with a moisture content greater than two percent above optimum should be moisture conditioned by windrowing and drying or wasted off site. Structural fill with a moisture content less than two percent below optimum should be blended with water to achieve the recommended moisture content. Fill Placement: Structural fill should be placed in horizontal lifts with a loose lift thickness appropriate for the material and energy of the compaction equipment used. If loose lift thickness greater than 12 inches are desired, the contractor should be required to demonstrate that the combination of fill material and compaction equipment can compact the entire lift thickness to the specified levels. Each lift of fill should be compacted to the minimum levels recommended above based on the maximum laboratory dry density as determined by the ASTM D1557 Modified Proctor Compaction Test. Underground Utilities 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. Such soils should be removed and replaced, if necessary. All structural fill used to replace over -excavated soils should be compacted as recommended in the Page 9