How To Build A Lasting Pool Foundation

As with a foundation on a home, the foundation of a swimming pool can experience sinking due to unstable or poorly compacted soil. Ensuring a pool is constructed on a deep, lasting foundation will protect the owner investment and save them from costly future repairs. Whether you're a contractor building a backyard pool or an indoor aquatic center, starting on a firm foundation is key for the long-term success of any project, and there are a wide range of variables in the design process.

Helical piles and anchors provide an exceptional pool foundation pier alternative to traditional deep foundation swimming pool support systems such as timber piling, concrete piling and drilled concrete piers. Helical piles have increasingly become the deep foundation design of choice for pool foundation construction due to superior performance, speed of installation, extremely low mobilization costs and the ability to overcome poor soil conditions.

Helical piles can be installed with smaller equipment and, oftentimes, the same equipment that is used to excavate the pool footprint. Small installation equipment allows greater flexibility with mobilization in and around existing structures with restricted access, whereas traditional methods have significant mobilization cost, site access challenges, and site disruption and clean-up.

A YMCA on the Florida Panhandle found CHANCE® Helical Pulldown Micropiles (HPM) to be the right foundation solution when project scheduling became a critical factor in building a new facility containing an indoor, accessible aquatic center with two pools. Plans called for the building and pool foundations to be supported by auger cast piles. The key to the project schedule would be installing the roof system as quickly as possible so that the building would be dried in so that weather could no longer affect the production schedule. For this to be accomplished the deep foundations for the pools would need to be installed after the roof was complete.

The CHANCE HPM is a technologically advanced, cost effective, high capacity deep foundation system. The HPM is a true composite pile that combines both skin friction and end bearing components to provide much higher capacities than provided by standard helical piles.

The pools were supported by a total of (36) Helical Pulldown Micropiles. Working loads per pile ranged from 65 to 100 kips in compression and 10 to 65 kips in tension. Pile depths ranged from 50 to 70 feet in length. Each pile was equipped with a 10” square new construction plate to allow for connection to the new poured concrete footings. Lead sections consisted of an 8710712714" helix configuration on a SS225 shaft (2-1/4” square). The grout column was 7" in diameter and provided an additional 3,000 lbs. of capacity per linear foot of grout column. A load test was conducted prior to production pile installation to verify the additional load that would be achieved by the grout column. All piles were installed to meet the design loads with a minimum factor of safety of two (2). Pile installation was completed in one (1) 40 hour work week.

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