A piled foundation was required for a new 36 m communication tower. Soils at the site were very weak inter-bedded layers of sands and silt, to depths beyond 40 m. A combination friction and end-bearing pile was chosen to gain as much capacity as possible from the weak soils and to try to stay as shallow as possible for costs.
A combination of torque derived capacity from the helices on the lead section and the bonded length from the 8 inch diameter grout column was used to achieve the design loads required. The pile selected was an Ideal Foundations, 2 7/8″ Stelcor pile. Piles were installed with an EX75 excavator with a 20,000 ft-lbs drive head.
A total of 10 piles were installed to an average depth of 55 feet with ultimate capacity per pile of 110 kips.