It may be determined by a soil test, excavation and visual or rational analysis
that a swimming pool requires a piling foundation.

The site should provide a minimum soil bearing capacity of 2000 p.s.f.

A geotechnical survey (soil test) is performed in or near the pool area. A test
boring is made utilizing a pipe and hammer, usually truck mounted. The soil
bearing capacity is determined by the amount of blows it takes to drive the
boring pipe a given length.

The soil composition is determined by withdrawing the boring pipe and examining
the contents at different depths. The geotechnical engineer will then make
recommendations as to the type and length of pilings. The swimming pool design
engineer will then determine the location, spacing, and quantity of piles.

There are several types of piling. The most common are:
auger cast piling
precast piling
helical piling
pin piling
timber piling

Some examples in which pilings are used.
A piling foundation is utilized in soft unstable soil conditions to
combat gravity, steep slopes, in high water table situations to resist
uplift and in coastal areas to resist storm surge.

Piling installations also require the pool structure be modified to
prevent punch through.

Site conditions or, the presence of muck, peat, silt, organic matter,
deleterious material, vegetation, soft and unstable soil are some
situations which may require soil stabilization or piling installation to
provide a suitable foundation for swimming pool construction

One alternate course of action to piling installation is to demuck or excavate
and remove all undesireable materials and replace with stone or fill and
compact. This is feasible in some cases based on depth of excavation, adjacent
structures, logistics and cost.

Construction using removal of undesireable material or fill, saturate and
compact all areas of construction with a self propelled heavy vibratory
roller to a minimum of 95% of the astm d-1557 modified proctor method.