Attachment D - GEO RPT_City of Sunny Isles BLDG Dept Relocation_S&S UPLOADED

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City of Sunny Isles Building Department Relocation Geotechnical Exploration Report Sunny Isles Beach, FL March 29, 2024 UES Project No.: 0630.2400024.0000 Page 7 of 9 4.0 FOUNDATION RECOMMENDATIONS 4.1 Helical Piles It is likely that a single helical pier can develop an allowable capacity of 12 kips (24 kips ultimate) at depths of approximately 24 feet below grade depending on shaft and helix configuration. Note that buckling effect was not determined. The designer should determine the buckling effect based on the shaft and helix configuration determined for design and construction. Appropriate reduction factors should be considered when center-to- center spacing of helical piles is less than three times the diameter of the largest helix plate at bearing depth. Helical piers consist of galvanized steel shafts with helical flight augers on the bottom shaft. The shafts are bolted together as the shafts are drilled into the subsurface. The torque applied to the piers during drilling is correlated to the compression capacity of the helical pier. The shafts are cut to the appropriate cut-off elevation, and typically pile caps, grade beams, or footings are cast on the top of the helical piers. Any footings that tie into existing footings should be doweled together. Where there are existing foundations, brackets can be attached to both the anchor and the foundation for support. To obtain the anticipated axial capacity, the piers would likely have to be installed and seated into gravelly and sandy soils encountered at approximately 24 feet below ground surface. Each pier must be installed with a minimum ultimate capacity of twice their design capacity. The capacity of each pier must be verified by shear pins or other calibration techniques as required by the Florida Building Code, latest ed., as noted below. In accordance with Section 1810.3.3.1.9 of the Florida Building Code, latest ed., the allowable axial design load, Pa, of helical piles shall be determined as follows: Pa = 0.5 Pu (Equation 18-4) where Pu is the least value of: 1.Sum of the areas of the helical bearing plates times the ultimate bearing capacity of the soil or rock comprising the bearing stratum. (In UES’s case, the designers can assume a soil’s unit weight (ϒ) of 110 pcf and an angle of shearing resistance (φ’) of 32o.) 2.Ultimate capacity determined from well-documented correlations with installation torque. 3.Ultimate capacity determined from load tests. 4.Ultimate axial capacity of pile shaft. 5.Ultimate axial capacity of pile shaft couplings. 6.Sum of the ultimate axial capacity of helical bearing plates affixed to pile. Helical pier design and installation are proprietary in nature. The locations and required capacity of the piers must be designed by the structural engineer or other qualified professional. UES recommends that a representative of UES’s company monitor the helical pier installation in accordance with the Florida Building Code.