Stone Town contacted EBS Geostructural to ask if our Chance square shaft helical piles would be able to penetrate through cobbles and small boulders. Changing soil conditions prevented further installation of 114mm ( 4 -1/2 inch) diameter round shaft helical piles to the required depth and tension capacity needed. With limited soils information and project timelines a consideration, EBS Geostructural mobilized on-site to install test helical piles.

EBS successfully installed several Chance SS175 Helical Piles (1-3/4 Inch solid square shaft) through the cobbles and small boulders to approximately 17 meters deep (9 meters deeper than any of the round shaft helical piles). EBS  Geostructural successfully completed two (2) tension tests to 400 kN (90 Kips) with a total helical anchor movement of less than 37mm (1.4 inches).
EBS Geostructural was awarded the remainder of the helical anchor installation.

One-hundred and sixty (160) Chance SS175 Helical Anchors were installed to an average depth of 16 meters from the bottom of the proposed structural slab in twenty (20) working days. The quicker pace for the square shaft Helical installation (approximately 33% faster than the round shaft) helped with the project schedule.
This project was an excellent example of the advantages the square shaft helical piles have over the round shaft or pipe helical piles in specific applications.