9930 19TH AVE SE 2018-01-02 MF Import

Geotechnical Engineering Report Home Base Warehouse - Everett July 31, 1997 NCA File No. 213497 Page 8 drying to a compactable condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction. Expected volumes of surface water in the wetland area are unknown. We expect recharge from ground water seepage during excavation to be low it' accomplished during dry weather, based on the low volumes of perched water observed in our test pits. We expect the surface water can be collected in sumps and pumped from the excavation. Water could be collected around the perimeter of the excavation in shallow trenches and directed to the sumps to maintain a water -free working surface in the excavation during structural fill installation. We would not expect water to present a problem with compaction after 3 to 4 feet of fill has been placed, provided free -draining fill with a low fines content is used for the initial fill. Foundations The foundations should placed on undisturbed medium dense to dense soil or on structural fill extending to these soils. The soil conditions should be evaluated for appropriate density at the time of construction. Exterior footings should extend a minimum of 18 inches below the adjacent ground surface with interior column footings a minimum of 12 inches below the bottom of the adjacent floor slab. Continuous and isolated spread footings should be at least 18 and 24 inches wide, respectively. If footings are constructed near slopes, the edge of the footing should be at least 5 feet back from the edge of the slope. All loose or disturbed soil should be removed from the foundation excavation prior to placing concrete. Standing water should not be allowed to accumulate in the building pad or footing trenches. Placement of rock spalls on the exposed soil may be required if wet conditions exist and the subgrade is being disturbed from construction traffic. For footings designed and constructed as recommended, we recommend an allowable design bearing pressure of not more than 2,500 pounds per square foot (psf) be used for design of the footings. Higher design bearing values may be feasible based on soil conditions, footing size and settlement tolerance. We recommend that we review the footing design if higher values are required. A one-third increese in the above allowable bearing pressure may be used when considering short-term transitory wind or seismic loads. NELSON-COUVRETTE 6 ASSOCIATES, INC.