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I of 6 <br /> LONGITUDE <br /> ONE TWENTYO <br /> ENGINEERING&DESIGN <br /> Pile Review for Structural Compliance <br /> Date: August 2nd, 2025 <br /> Project Name: Foundation Stabilization/Lift — Everett Project Number: S241230-2XR <br /> Project Location: 2022 Oakes Ave, Everett, WA 98201 <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 January 181h <br /> 2025. <br /> During the week of February 261h, 2025, two (2) helical piles were installed by R&R Foundation Specialists <br /> (R&R) to stabilize areas of the single-family residence located at 2022 Oakes Ave, Everett, WA 98201. To <br /> the knowledge of L120, these piles were installed by R&R certified installers in accordance with the cited <br /> structural package, ESR-5049. Please refer to the attached drive log and photographs provided by R&R. <br /> The FOR from L120 Engineering and Design was present on site during the pile installation. <br /> The helical piles were installed with maximum pile spacing of 6'-0"on-center, the typical minimum required <br /> vertical capacity as determined by L120 is shown in the table below. These demand requirements are as <br /> 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 /> 200%MIN VERTICAL <br /> PILE# PILE TYPE LOCATION <br /> BTWN PILES END OFFSET ALLOWABLE LOADING CAPACITY <br /> (MIN ULTIMATE CAPACITY) <br /> TYP HFI ICAI PER PLAN 17.0 k/PILE 34.0 k1PILE CHIMNEY <br /> Pile capacities for the helical piles have been calculated using a Digga HH-6K drive head with a torque <br /> correlation factor, Kt, of 9 as prescribed in ESR-5049. 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 1,250 psi results in a maximum allowable capacity of 17.5 kips including a safety <br /> factor of 2. <br />