We recognized that this was an issue which required immediate attention so the project could proceed on time. Once the issue was identified, Coastal Foundation Solutions secured the services of Ruben Clarsen Consulting to provide engineered plans for the helical anchor tie-back installation.
Coastal Foundation Solutions proceeded exactly as planned with equipment mobilization to Captiva Island with no delays or interruptions. We maintain a fleet of modular barges to be transported into any type of waterbody, even land locked lakes.
The design entailed installation of forty-eight (48) 1 ½” square shaft Seawall Saver helical anchors placed on 7 foot centers. Additional anchors were required to be installed on each immediate side of expansion joints.
The helical tie-back anchors and installation equipment were transported to Captiva Island by Coastal Foundation Solutions custom construction barge. The new seawall panels had been installed and access from the upland portion of the project site was non-existent. Thus, the helical tieback anchors were installed with specialized equipment mounted to a hydraulic excavator.
Forty-Eight (48) Seawall Saver (1 ½” inch square bar) helical tieback anchors with a 6”-6”-6” triple-helix lead section was installed over the top of existing concrete seawall slabs. Coastal Foundation Solutions utilized a Caterpillar excavator with a specialized mast system powered by a 6K Eskridge drive head to install the helical anchors. Seawall Saver Helical extensions imbedded the tieback anchors to lengths of 15 to 21 feet to attain final installation torques.
The helical tieback anchors were hydraulically rotated to 2,000 P.S.I., providing a tension load of 12 kips.
One hundred and twenty-two (122) additional 1 ½” extensions were used to attain dynamic load capacity due to sub-surface soil disparities.
The helical tie back anchor was linked to a hot dipped galvanized “C” steel channel, placed within the seawall cap to provide lateral structural support. All tiebacks and anchors were installed with a Digital Torque Indicator to insure required engineered load capacity.