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Limited Geotechnical Engineering Study <br /> View Ridge Elementary School Portable Classroom Installation <br /> Everett, Washington and Downspout Infiltration Feasibility <br /> The site preparation recommendations presented above rely on existing fill soils to support the <br /> new portable classrooms. It is possible that some future foundation settlement could occur due <br /> to settlement within the existing fill. Typically for portable buildings any settlement does not <br /> create an unsafe condition and is easily corrected by adding shims or adjusting jacks below the <br /> building, and therefore the cost of removing and replacing existing fill is not warranted. If the risk <br /> of future settlement and releveling of portable classroom foundations is not acceptable, all <br /> existing fill should be removed below the portable classrooms and replaced as needed with new <br /> structural fill. <br /> Structural Fill <br /> All references to structural fill in this limited study refer to subgrade preparation, fill type, <br /> placement, and compaction of materials as discussed in this section. <br /> After stripping, planned excavation, and recommended overexcavation have been performed to <br /> the satisfaction of the geotechnical engineer/engineering geologist, the exposed soil should be <br /> compacted to a firm and unyielding condition. If the subgrade contains too much moisture, <br /> adequate compaction may be difficult or impossible to obtain and should not be attempted. <br /> After recompaction of the exposed ground, structural fill may be placed to attain desired grades. <br /> Structural fill placed below portable building pads should consist of a granular imported material <br /> such as crushed base course or clean chip rock which are free of organics and other deleterious <br /> materials, placed in maximum 8-inch loose lifts. Each lift should be compacted to 95 percent of <br /> the modified Proctor maximum density using ASTM D-1557 as the standard. In the case of utility <br /> trench filling,the backfill should be placed and compacted in accordance with applicable codes <br /> and standards. <br /> Shallow Foundations <br /> The portable classroom foundations should be supported directly by the medium dense existing <br /> fill or structural fill placed over these materials and compacted to at least 95 percent of the <br /> modified Proctor maximum dry density as determined by ASTM D-1557.An allowable foundation <br /> soil bearing pressure of 1,500 pounds per square foot (psf) is recommended for design of <br /> foundations supported as recommended above. This value may be increased by one-third to <br /> accommodate transient wind or seismic loads. Foundations constructed as recommended are <br /> expected to settle up to 1 inch, with differential settlement up to approximately one-half of the <br /> total settlement. <br /> July 12,2023 ASSOCIATED EARTH SCIENCES,INC. <br /> BCY/Id-20100255E004-002 Page 7 <br />