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1 of 6 <br /> LONGITUDE <br /> ONE TWENTY° <br /> ENGINEERING&DESIGN <br /> Helical Pile Review for Structural Compliance <br /> Date: March 7, 2024 <br /> Project Name: 7211 Beverly Blvd- Foundation Stabilization Effort L120 Project#S230731-2XR <br /> Project Location: 7211 Beverly Blvd, Everett, WA 98203 <br /> Client's Name:A Montoya, Project Coordinator— 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 /> August 9,2023. <br /> On March 4-5,2024,five(5) helical piles were installed by R&R Foundation Specialists(R&R)to stabilize and lift the <br /> residence located at 7211 Beverly Blvd.The FOR from L120 Engineering was present on site during the pile <br /> installation. Piles were installed with a DIGGA 10k drive head to a maximum depth of 10ft.To the knowledge of <br /> L120,these piles were installed by R&R certified installers in accordance with the cited structural package and ESR- <br /> 3750. Please refer to the attached drive log provided by R&R. <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 9.0 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 to be performed to 200 percent of the <br /> specified design load. It is L120's understanding that the installers utilized the dead weight of the existing structure <br /> to achieve the required reaction of a test pile. <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 700psi results in an <br /> installation torque of 2,436 ft-lbs,and an allowable capacity of 11.0 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)= 11.0 kips/pile <br /> 4. •a 790 9502 <br />