ob Wason has been building pools for decades, but he says he always manages to learn something new with every job.

On this job, it was the underground vault his team had to install to house the equipment and controls for this project’s vanishing edge and lower waterfalls. They took a modified septic tank measuring a mere 7-feet-by-7-feet-by-10-feet tall and equipped it with a manhole cover for access.

“We learned a whole different ballgame,” says Wason, a principal of Gym & Swim in Louisville, Ky. “We had to provide protection from flooding from rainwater. We had to provide ventilation and underground lighting. We had to have a custom ladder made so you can go down into the vault.” They also had to order only equipment that would fit in the 3-foot-diameter entrance.

To drain the vault, the workers installed several gravity drains on the floor. Water flowing from the vault will go into the lake. They ventilated the space with exhaust fans. They waterproofed the vault walls to prevent seepage, and all lighting and electrical connections had to be corrosion-proof because of the humidity that can accumulate in such a small underground space.

“You couldn’t use chlorine in a situation like this,” he says. “You couldn’t go down and open a drum of chlorine — there wouldn’t be any way to get away from the fumes, even with the power vents. So we had to go with an ionization unit.”
They learned important lessons, too, about working in the vault, where they now provide regular service. A costly lesson came when one of the workers removed a plastic bag off a piece of equipment and left it on the vault floor. It plugged the drain during a flash flood, which submerged the equipment and destroyed it. “It was a very expensive lesson,” Wason says.

Management also has to be careful about which service technicians it assigns to the project. The technician must fit through the hole and not be subject to claustrophobia. “It would be like being in a submarine,” Wason says.