7423 LOWER RIDGE RD 2024-10-25 - Laserfiche WebLink

• February 1,2024 Page 3 of 3 Limited Geotechnical Evaluation hard soils. Dependent on the pile size and the equipment used to install the anchors,an empirical factor is multiplied by the average torque over the final 3 feet of installation to estimate ultimate capacity. Allowable Helical Pier Compression Capacity Pa may be estimated from the following equation provided that the pier is in the recommended bearing soils: Pa=Kt x T/FoS, Where T is the applied torque, Kt is the empirical ratio factor. The following industry standards apply to shafts with blades spaced along the shaft at 2.5 to 3.5 times the average blade diameter on- center and meeting the manufacturer's specifications. 1.5"and 1.75"Square Shafts - Kt=9 ft-i 2.875"O.D.Round Shafts - Kt=9 ft-i 3.0"O.D.Round Shafts - Kt=8 ft-1 3.5"O.D.Round Shafts - Kt=7 ft-1 Proof testing of at least three percent of the helical piers in eight equal increments up to 200 percent of the design load, if required by the permitting authority. Each load increment up to the 200 percent of design load should be held for five(5)minutes and the vertical strain monitored. If the total strain between 1 and 5 minutes is less than o.04 inches,the helical pier may be considered acceptable. If the recorded strain exceeds o.04 inches,the helical pier should either be deepened and retested or abandoned and a new helical pier shall be installed and tested. Closure The information presented herein is based upon professional interpretation utilizing standard practices and a degree of conservatism deemed proper for this project. We emphasize that this report is valid for this project as outlined above and for the current site conditions and should not be used for any other site. Sincerely, Cobalt Geosciences,LLC 40% tic WAS , �/ n -off 54896 iSt`'OHM. 2/1/2024 Phil Haberman,PE,LG,LEG Principal Figure 1;Site Plan Figure 2;Repair Plan Figure 3;Hand Boring Log www.cobaltgeo.com (206)331-1097 Iri