6202 ASSOCIATED BLVD Geotech Report 2022-10-25

Proposed Everett Warehouse ZipperGeo March 5, 2019 such that the bottom footing elevation of 424 feet is located at least 50 feet from the northwest building corner. We recommend that all continuous wall and isolated column footings be at least 12 and 24 inches wide, respectively. General Footing Subgrade Preparation We expect soil conditions encountered at footing subgrade elevations will consist of existing undocumented fill soils or structural fill placed to raise site grades. Where footing subgrades expose undocumented fill, some mitigative subgrade preparation may be required to achieve adequate foundation support. This mitigative work may include over -excavation and replacement with compacted structural fill or simply compacting the subgrade to a firm and unyielding condition. The extent to which mitigative work will be required will not become evident until footing subgrades are exposed and observed by a qualified geotechnical engineer. We therefore recommend that the footing subgrades be observed by a qualified geotechnical engineer during construction to determine if and what mitigative work is required. Footing subgrade soils will be susceptible to disturbance during wet weather. As a precautionary measure, consideration should be given to protecting prepared footing subgrades from wet weather by placing a thin layer of controlled density fill or lean mix concrete atop them. Shallow Foundation Allowable Bearing Pressure For footings founded on subgrades prepared as recommended in this report and any subsequent field recommendations during construction, we recommended an allowable bearing pressure of3,000 psf. The above -recommended bearing pressure generally assumes that most footings will be founded on undocumented fill, or structural fill used to raise site grades, all of which are prepared in accordance with the recommendations in this report including any field -recommended mitigative work. A one-third increase of the bearing pressure recommended above may be used for short-term transient loads such as wind and seismic forces. Lateral Resistance Resistance to lateral loads can be calculated assuming an ultimate soil passive resistance of 450 pcf equivalent fluid pressure (triangular distribution) and an ultimate base friction coefficient of 0.50. An appropriate safety factor (or load/resistance factors) should be included for calculating resistance to lateral loads. For allowable stress design, we recommend a minimum 1.5 safety factor. We recommend that passive resistance be neglected in the upper 18 inches of embedment. The above -recommended soil passive resistance assumes any structural fill used to backfill footing excavations is placed and compacted in accordance with the recommendations presented in this report. Estimated Foundation Settlements Provided fill and footing subgrades are prepared in accordance with the recommendations in this report, and provided that subsurface soil conditions at locations not explored are similar or better to those Page 12