Helical Piles Installed for YMCA in Fond du Lac, WI

Challenge

In 2009 the YMCA began construction of a 13 million dollar addition. The new addition was to include a new child care area, locker rooms, workout studios and natatorium. The natatorium consisted of a large indoor water-park including 29’ X 76’ lap pool with 3’6” shallow end and 9’3” deep end. During excavation of the pool, the pool contractor discovered the presence of unsuitable organic soils. It was determined that to prevent future settlement, the pool would need to be supported on a deep foundation. Since the structures exterior shell had already been erected, helical piles were selected as the ideal foundation support option given the limited site access and limited ground disturbance.

Solution

The soil tests indicated we would need to install the piles to a depth of 30 to 40 feet. It was determined that 34 Foundation Supportworks Model 350 Helical Piles would be needed to carry a design load of 65 kips per pile. A temporary earthen ramp was constructed to create access for equipment and materials. The contractor located and marked the pile cap locations. FSIWI installed 16 piles in the deep end to average depths of 26 feet below pool bottom and 18 piles in the shallow end to an average depth of 33 feet below pool bottom. Once the piles reached the proper torque the piles were cut to the necessary elevation and a 12”X12” plate was welded on top of each pile cap. FSIWI was able to install the 34 piles in two and half days to an average depth of 37 feet from deck grade. The piles were driven to a torque of 14,285 ft-lbs. giving an ultimate load of 97.5 kips at a factor of safety of approximately 1.5.

Project Summary

Architect: Zimmerman Architectural Studio Inc.

Structural Engineer: GRaEF Engineering

Geotechnical Engineer: Midwest Engineering Services

Certified Installer: Foundation Supportworks of WI

Products Installed: (34) FSI Model 350 Helical Piles