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Subsurface Exploration,Geologic Hazards,and Former Brien Ford Preliminary Geotechnical Engineering Report Everett, Washington Preliminary Design Recommendations dense bearing layer will likely vary with location. However, all pipe piles must meet the following requirements: • The piles must fully penetrate through the existing fill soils and ice-contact deposits and embed into the underlying advance outwash deposits. • The piles must extend at least 5 feet below the planned excavation depth. • The piles must meet the refusal criteria for the allowable design load. Meeting the above criteria may require pile driving beyond the minimum refusal criteria, using an oversize pile hammer, pre-excavation, or a combination thereof to reach the minimum embedment depths. We recommend that actual pile embedment be determined in the field by an AESI geotechnical engineer, or their representative,who can interpret and collect the pile installation data and observe the contractor's operations. AESI, acting as the owner's field representative, would determine the required pile lengths and keep records of pertinent installation data. If a more accurate estimate of the total required pile lengths for foundation support are desired before construction we recommend that this be determined through the installation of test piles. Pipe pile foundation design parameters are provided in Table 1. Table 1 Pipe Pile Design Parameters Allowable Vertical Minimum Nominal Pile Hammer Weight Pile Capacity Driving Time Diameter Wall Thickness (pounds)Class (kips) (seconds per inch) 3 inches Schedule 40 1,100 12 6 4 inches Schedule 40 1,100 20 10 Anticipated settlement of pile-supported foundations should be less than 1/2 inch. Pile installation must be observed by AESI to verify that the design bearing capacity of the piles has been attained and that construction conforms to the recommendations contained herein. The City may also require such inspections. Any encountered existing fill may contain construction debris such as: concrete, brick, wood, and other construction waste; therefore, it may be necessary to have a backhoe present during pile installation to dig out obstacles and backfill the excavation. If obstacles are encountered at depths where removal with a backhoe is not feasible, it might be necessary to modify the pile layout to replace piles that cannot be completed according to the original design. May 16,2017 ASSOCIATED EARTH SCIENCES,INC. AWR/Id-160594V003-2-Projects1201605941KVIWP Page 12