Building a pool on Beaumont clay

What the soil survey says

USDA first described the Beaumont series in Jefferson County in 1947, from a field off South China Road west of town. It's a poorly drained clay in slight depressions on the coastal plain, with cracks 1–2 cm or wider and at least 30 cm deep in dry spells, and the hummocky "gilgai" ground that swelling clay creates (Beaumont series). The neighboring League series is somewhat poorly drained, high in shrink-swell, and holds perched water 6–30 in down from January to March (League series).

What swelling clay does to a pool

Clay swells when it gets wet and shrinks as it dries, and that movement can crack a deck, pull coping loose or lift a shell. A small leak makes it worse: water seeping into the clay keeps it swelling on one side (Pool & Spa News). After a dry summer, the first heavy rain is when movement often shows.

How builders handle it

• Dig deeper than the pool and replace the bottom layer with crushed stone or select fill
• Use extra steel in the shell and deck where the engineer calls for it
• Expansion joints between deck and coping
• Deck drains and a yard graded so rain runs away from the pool
• A hydrostatic relief valve in the main drain

Ask each bidder which of these are included. If one bid is far lower, this list is often why.

Digging in a wet winter

From January to March, expect water in the hole on many lots. Crews pump from a sump in the deep end while they work. Agree in writing who pays if pumping runs for days; we use $1,500–6,000 for clay and water work as an estimate.

Owner habits that protect the pool