703 NILES AVE 2024-11-08 - Laserfiche WebLink

I of 6 LONGITUDE ONE TWENTYO ENGINEERING&DESIGN Pile Review for Structural Compliance Date: September 11th, 2024 Project Name: Foundation Stabilization— Everett Project Number: S240722-2XR Project Location: 703 Niles Ave, Everett, WA 98201 Client's Name: R&R Foundation Specialist, LLC To Whom It May Concern: The purpose of this letter is to confirm pile installation and capacity compliance with the structural re- quirements specified in the L120 Structural Calculation Package and Structural Site Plan dated July 23ra 2024. Fourteen (14) helical piles were installed by R&R Foundation Specialists (R&R) to stabilize areas of the single-family residence located at 703 Niles Ave, Everett, WA 98201. To the knowledge of L120, these piles were installed by R&R certified installers in accordance with the cited structural package, ESR-3750. Please refer to the attached drive log and photographs provided by R&R.The FOR from L120 Engineering and Design was present on site during the pile installation. The helical piles were installed with maximum pile spacing of 6'-0"on-center, the typical minimum required vertical capacity as determined by L120 is shown in the table below. These demand requirements are as determined and specified in L120's structural calculation package cited above. PILE SPACING&LOAD REQUIREMENTS TABLE MAX O.C.SPACING,ft MIN VERTICAL CAPACITY, kips PROOF TESTING LOAD,kips 200%MIN VERTICAL PILE# PILE TYPE LOCATION BTWN PILES END OFFSET ALLOWABLE LOADING CAPACITY (MIN ULTIMATE CAPACITY) 1-2,9-14 14.0 k/PILE 28.0 k/PILE EXTERIOR 3-5 HELICAL 6'-0" PER PLAN 17.0 k/PILE 34.0 k/PILE EXTERIOR 6-8 11.0 k/PILE 22.0 k/PILE EXTERIOR Pile capacities for the helical piles have been calculated using a Digga MM-10K drive head with a torque correlation factor, Kt, of 9 as prescribed in ESR-3750. A chart showing the resulting capacities is attached to this letter. Per the attached document, an Ideal Foundation Systems 2-7/8" diameter helical pile installed to a minimum pressure of 1,200 psi results in a maximum allowable capacity of 18.8 kips including a safety factor of 2.