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1 <br /> Subsurface Exploration, Geologic Hazards, and <br /> Proposed James Monroe Elementary School Replacement Revised Geotechnical Engineering Report <br /> Everett, Washington Design Recommendations <br /> ' moisture conditions can be controlled by aeration and drying, as needed. If fill is placed <br /> during wet weather or if proper compaction cannot be obtained, a select import material <br /> consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill <br /> consists of non-organic soil with the amount of fine-grained material limited to 5 percent by <br /> weight when measured on the minus No. 4 sieve fraction with at least 25 percent retained on <br /> ' the No. 4 sieve. <br /> A representative from our firm should inspect the stripped subgrade and be present during <br /> ' placement of structural fill to observe the work and perform a representative number of <br /> in-place density tests. In this way, the adequacy of the earthwork may be evaluated as filling <br /> progresses, and any problem areas may be corrected at that time. It is important to understand <br /> ' that taking random compaction tests on a part-time basis will not assure uniformity or <br /> acceptable performance of a fill. As such, we are available to aid the school district in <br /> developing a suitable monitoring and testing program. <br /> 11.0 FOUNDATIONS <br /> ' Spread footings may be used for building support when founded directly on undisturbed <br /> lodgement till sediments, or on structural fill placed above suitable native deposits, as <br /> ' previously discussed. We recommend that an allowable bearing pressure of 3,000 pounds per <br /> square foot (psf) be used for design purposes, including both dead and live loads. An increase <br /> of one-third may be used for short-term wind or seismic loading. Higher foundation soil <br /> ' bearing pressures are possible for foundations supported entirely on undisturbed lodgement till. <br /> For foundations supported entirely on undisturbed lodgement till, an allowable foundation soil <br /> bearing pressure of 5,000 psf may be used. If higher foundation soil bearing pressures are <br /> needed, we should be allowed to offer situation-specific recommendations. <br /> Perimeter footings should be buried at least 18 inches into the surrounding soil for frost <br /> ' protection. However, all footings must penetrate to the prescribed bearing stratum, and no <br /> footing should be founded in or above organic or loose soils. All footings should have a <br /> minimum width of 18 inches. <br /> It should be noted that the area bound by lines extending downward at 1H:1V from any footing <br /> must not intersect another footing or intersect a filled area that has not been compacted to at <br /> least 95 percent of ASTM:D 1557. In addition, a 1.5H:1V line extending down from any <br /> footing must not daylight because sloughing or raveling may eventually undermine the footing. <br /> Thus, footings should not be placed near the edge of steps or cuts in the bearing soils. <br /> ' Anticipated settlement of footings founded as described above should be on the order of 3/4 inch <br /> or less. However, disturbed soil not removed from footing excavations prior to footing <br /> ' placement could result in increased settlements. All footing areas should be inspected by AESI <br /> prior to placing concrete to verify that the design bearing capacity of the soils has been attained <br /> ' October 5, 2009 ASSOCIATED EARTH SCIENCES, INC. <br /> IJWG/td-KE09031 24 3-Projects1200903I 2tKElWP Page 16 <br />