Length of the Deep Foundation.

The length of the deep foundation is generally dependent on topography and soil conditions of the site.

(1) Driven piles. Pile length is controlled by soil conditions and location of a suitable bearing stratum,
availability and suitability of driving equipment, total pile offshore.  Piles up to 150 feet are technically and economically weight, and cost.  Piles exceeding 300 feet have been installed acceptable for onshore installation.

(2) Drilled shafts. Shaft length depends on the depth to a suitable bearing stratum.  This length is limited by the capability of the drilling equipment and the ability to keep the hole open for placement of the reinforcement steel cage and concrete.