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1 of 6 <br /> LONGITUDE <br /> ONE TWENTYO <br /> ENGINEERING&DESIGN <br /> Helical Pile Review for Structural Compliance <br /> Date: February 5, 2024 <br /> Project Name: 2303 Oakes Ave- Foundation Stabilization Effort L120 Project#S221213-2XR <br /> Project Location: 2303 Oakes Ave, Everett, WA 98281 <br /> Client's Name: R&R Foundation Specialist, LLC <br /> To whom it may concern, <br /> The purpose of this letter is to confirm helical pile installation and capacity compliance with the structural <br /> requirements specified in the L120 Structural Calculation Package and Structural Site&Foundation Plan dated <br /> January 3,2023. <br /> On January 8-9,2024,the installation of twelve(12) helical piles to lift and stabilize areas of the residence located <br /> at 2303 Oakes Ave were finalized by R&R Foundation Specialists(R&R).The FOR from L120 Engineering was <br /> present on site during the pile installation. Piles were installed with a DIGGA 10k drive head to a maximum depth <br /> of 12ft and were installed by R&R certified installers in accordance with the cited structural package and ESR-3750. <br /> Please refer to the attached drive log. <br /> With pile spacing at a maximum 6'-0"on-center,the minimum required vertical capacity as determined by L120 <br /> was allowable loadings of 9 kips per pile.These demand requirements are as determined and specified in L120's <br /> structural calculation package cited above. <br /> As required by the referenced structural package, proof testing was performed to 200 percent of the specified <br /> design load.The installers utilized the dead weight of the existing structure to achieve the required reaction of the <br /> test piles. <br /> Pile capacities for helical piles have been calculated utilizing the torque correlation factors provided in ESR-3750.A <br /> torque/capacity chart detailing this calculation has been attached to this letter. Per the attached document,an <br /> Ideal Foundation Systems 2-7/8in diameter 10k helical pile installed to minimum pressures of 1,100psi results in an <br /> installation torque of 3,828 ft-lbs,and an allowable capacity of 17.2 kips including a safety factor of 2. <br /> The results are summarized below: <br /> Maximum Demand (allowable)=9.0 kips/pile <br /> Available Capacity(allowable) = 17.2 kips/pile <br /> 4. •6)790 9502 <br />