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I of 5 <br /> LONGITUDE <br /> ONE TWENTYO <br /> ENGINEERING&DESIGN <br /> Pile Review for Structural Compliance <br /> Date: March 21", 2023 <br /> Project Name: Foundation Stabilization/Lift — Everett Project Number: S220112-3XR <br /> Project Location: 5008 23rd Ave W, 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 re- <br /> quirements specified in the L120 Structural Calculation Package and Structural Site Plan dated April 13th <br /> 2022. <br /> During the week of August 29th, 2022, twelve (12) helical piles were installed by R&R Foundation Specialists <br /> (R&R) to stabilize areas of the single-family residence located at 5008 23rd Ave W, Everett, WA 98203. To <br /> the knowledge of L120, these piles were installed by R&R certified installers in accordance with the cited <br /> structural package, ESR-3750. Please refer to the attached drive log and photographs provided by R&R. <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 /> PILE# PILE TYPE 200%MIN VERTICAL CAPACITY LOCATION <br /> BTWN PILES END OFFSET ALLOWABLE LOADING <br /> (MIN ULTIMATE CAPACITY) <br /> 1-2 8.0 k/PILE 16.0 k/PILE EXTERIOR <br /> 3 7 12.0 k/PILE 24.0 k/PILE EXTERIOR <br /> EHELI(-AL 6'-0" PER PLAN <br /> 917.0 k/PILE 34.0 k/PILE EXTERIOR <br /> 12 16.0 k/PILE 32.0 k/PILE DECK <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 2,000 psi results in a maximum allowable capacity of 31.3 kips including a safety <br /> factor of 2. <br />