1310 SE EVERETT MALL WAY Geotech Report 2022-10-25

' Darden Restaurants, Inc. September 15,2011 Proposed Olive Garden—Everett,Washington Page 6 of 12 upon the weather conditions at the time of grading, moisture conditioning of the soils to achieve near optimum moisture content of the soils prior to densification may be needed. If the recommended level of compaction is not achieved it will be necessary to perform additional surface compaction or overexcavate portions of the fill and replace these soils as Structural Fill. PSI will be available to provide this evaluation at the time of construction. Following adequate densification, low areas may be raised to planned finished grade with Structural Fill. 3.3 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 be evaluated by a PSI representative before filling or construction begins. Fill 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. The granular on-site soils are suitable for use as structural fill provided the soil can be properly 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 moisture conditioned to about 0 to 3 percent above the soil's optimum moisture content, 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 American Society for Testing and Materials (ASTM) D698. Silty soil is sensitive to small changes in moisture content and may be difficult, if not impossible, to compact adequately during wet weather, in confined spaces or when the moisture content is more than a few percentage points above the optimum moisture content. We recommend using imported granular material for structural fill if the on-site material cannot be properly moisture conditioned. Imported granular material for structural fill should consist of 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 12 inches and compacted to not less than 95 percent of the maximum dry density as determined by ASTM D698. During the wet season or when wet subgrade conditions exist, the initial lift should be approximately 18 inches in uncompacted thickness and should be compacted by static rolling with a smooth drum roller. 3.4 Shallow Foundations Desiqn Following site grading, as recommended, it is our opinion that conventional spread and continuous footings founded on medium dense or firmer existing soils or structural fill will provide adequate support for the proposed structure. We offer the following comments and recommendations for purposes of footing design and construction. Footings should not be cast on loose, soft, or frozen soil; slough; debris; or surfaces covered by standing water. We recommend that the geotechnical engineer test the soils at the base of the footing excavations to document that the soils have been adequately densified, as previously recommended. If loose or inadequately densified soils are present, these soils should either be removed and replaced as a Structural Fill, or the loose soils may be densified in-place as recommended by the geotechnical engineer.