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I of 9 <br /> LONGITUDE <br /> ONE TWENTYO <br /> ENGINEERING&DESIGN <br /> Pile Review for Structural Compliance <br /> Date: April 17th, 2024 <br /> Project Name: Foundation Stabilization/Lift — Everett Project Number: S230726-1XR <br /> Project Location: 1049 Crown Dr, Everett, WA 98203 <br /> Client's Name: R&R Foundation Specialist, LLC <br /> To Whom It May Concern: <br /> The purpose of this letter is to confirm pile installation and capacity compliance with the structural require- <br /> ments specified in the L120 Structural Calculation Package and Structural Site Plan dated September 17th <br /> 2023. <br /> During the week of February 1St, 2024, ten (10) helical and two (2) concentric piles were installed by R&R <br /> Foundation Specialists (R&R) to stabilize areas of the single-family residence located at 1049 Crown Dr, <br /> Everett, WA 98203. To the knowledge of L120, these piles were installed by R&R certified installers in <br /> accordance with the cited structural package, ESR-3750 and ESR-4121. Please refer to the attached drive <br /> log and photographs provided by R&R. <br /> Cobolt Engineering was present on site during the pile installation. <br /> The helical and concentric piles were installed with maximum pile spacing of T-0"on-center, the typical <br /> minimum required vertical capacity as determined by L120 is shown in the table below. These demand <br /> requirements are as determined and specified in L120's structural calculation package cited above. <br /> PILE SPACING&LOAD REQUIREMENTS TABLE <br /> MAX O.C.SPACING,ft MIN VERTICAL CAPACITY,kips PROOF TESTING LOAD,kips <br /> PILE# PILE TYPE 200%MIN VERTICAL CAPACITY LOCATION <br /> BTWN PILES END OFFSET ALLOWABLE LOADING <br /> (MIN ULTIMATE CAPACITY) <br /> 1-2,8-10 HELICAL 7,0„ 11.0 k/PILE 22.0 k/PILE EXTERIOR <br /> 3-7 HELICAL PER PLAN 7.0 k/PILE 14.0 k/PILE EXTERIOR <br /> 2-8 CONCENTRICI PER PLAN 18.0 k/PILE 36.0 k/PILE CHIMNEY <br /> Pile capacities for the helical piles have been calculated using a Digga MM-10K drive head with a torque <br /> correlation factor, Kt, of 9 as prescribed in ESR-3750. A chart showing the resulting capacities is attached <br /> to this letter. Per the attached document, an Ideal Foundation Systems 2-7/8" diameter helical pile installed <br /> to a minimum pressure of 1,000 psi results in a maximum allowable capacity of 15.7 kips including a safety <br /> factor of 2. <br /> Pile capacities for the concentric piles have been calculated utilizing the effective cylinder area of the Power <br /> Team C25C hydraulic cylinder used with the Stabil-Loc Foundation Piering Systems assembly. A chart <br />