4815 EVERGREEN WAY 2016-01-01 MF Import

JP Morgan Chase April 29, 2010 Geotechnical Investigat ion Proposed Chase Bank Everett, WA PSI Report No. 0704186 Within pavement areas, trench backfill placed within 3 feet of finished grade should be compacted to at least 95 percent of the maximum dry density as determined by American Society for Testing and Materials (ASTM) D698. 4.5 STRUCTURAL FILL Regardless of material or location, structural fill should be placed over firm, unyielding subgrade prepared in accordance with the "Site Preparation" section of this report. The condition of the subgrade should t�e evaluated by a PSI representative before filling or construction begins. Fiil soil compaction should be evaluated by in-place density tests performed during fill placement so that adequacy of soil compaction efforts may be evaluated as earthwork progresses. When fill material is inconsistent or when particie sizz is greater than 1Yz-inch diameter, fill placement should be observed and compaction evaluated by observation of a proofroll or the operation of heavy rubber tired construction equipment. The on-site soils are suitable for use as structuraf fill provided the soil can be moisture- conditioned. On-site material used as structural fill should be free of organic material or other unsuitable materials and particles larger than 6 inches in diameter. The fill should be placed in lifts with a maximum uncompacted thickness of 8 inches, and compacted to not less than 95 percent of the maximum dry density as determined by ASTM D698. The onsite soils are sensitive to small changes in moisture content and may be di�cult, if not impossible, to compact adequately during wet weather or when their moisture content is in excass of the optimum moisture content. We recommend using imported granular material for structural fill if the on-site material cannot ba moisture conditioned. Imported granular material for structural fill should be pit-run or quarry-run rock, crushed rock, crushed gravel, or sand. It should be fairly well-graded between coarse and fine material and have less than 5 percent by weight passing the U.S. Standard No. 200 Sieve. The material should be placed in lifts with a maximum uncompacted thickness of 8 inches and compacted to not less than 95 percent of the maximum dry density as determined by ASTM D698. During the wet season or wlien wet subgrade conditions exisl, the initial lift should be approximately 18 inches in uncompacted thickness and should be compacted by static rolling with a smooth drum roller. 4.6 SHALLOW FOUNDATIONS In our opinion, conventional spread and continuous footings founded on the on-site soils (existing fill as well as native sand and gravel) will provide ade!�uate support for the proposed structure. The on-site fill materials have been previously consolidated due to the dead load of the existing structure and any elastic (short term) settlements within the fill has already ..�. rJ• s