Best-Practice Solution for Leaking Surge Tanks

Project: Kaplan Center Natatorium Surge Tank

Project Location: the University of North Carolina at Greensboro

Problematic water vessels are the worst. We know. The stress that occurs with the frustration of not understanding why a problem has made itself evident is something that even gets to the best of us.

This was the case with the fourteen-foot-deep surge tank in Kaplan Center Natatorium at the University of North Carolina at Greensboro. There was a leaking problem where the source could not be found, and with surge tanks, this isn’t an issue that can be put to the side.

Surge tanks are required in pools where large amounts of people are expected to be in it at the same time; for example, public swimming pools, or in this specific case, a college campus swimming pool. They are required because when a swimming pool is busy, the volume of swimmers displaces an equal volume of water. Rather than allowing the displaced water to spill out onto the pool deck, a gutter is built around the perimeter that allows the water to temporarily relocate into the surge tank. Once a swimmer leaves the pool, the water is pumped back into the pool from the surge tank to replace the swimmer’s volume.

Entrance to the surge tank.

Skanska, the general contracting group assigned to this project by the school, was working with Paddock Pool Equipment Company to fix this problem. A number of solutions to seal the tank were considered, from reapplying another surface waterproof coating to an epoxy-based liner; however, the need to complete the repair quickly was the top priority.

Completely draining and drying the tank along with prepping the existing surface to allow an adhesive-based solution to be installed was out of the question.

This is when Paddock proposed a solution in which a PVC liner would be installed and knew Ultimate Pool Surface 60 MIL membrane was the answer. This solution with our product was the only one that could be done quickly with minimal downtime to the tank.

Once one of our certified poolForce installers were contacted about this project, things started moving rather quickly. Paddock provided all the PVC piping themselves and made it in-house at their facility in Rock Hill, South Carolina.

Something that was done differently on this specific project was instead of continuing just our membrane on the floor of the water vessel, a half inch thick PVC slab was made to cover the entire floor of the surge tank. Because the PVC slab was too big to fit through the door at the top of the tank, there was no other option but to cut the piece into two pieces. Once the two pieces were in their rightful places on the floor of the tank, they were welded together to assure no water would seep through.

Certified installer installing a termination piece.

Termination pieces were another necessity to this specific project because we had to apply them to the water pipes inside the tank. Termination pieces are round pieces of PVC piping that must be placed around the interior surge tank pipes and welded to them. This was required because without the PVC piping, there would be nothing to weld the material to, resulting in a way for water to leak out of the tank. This was the same case with the hydrostatic valve at the bottom of the tank.

The surge tanks for the pools at the new UNC Greensboro Kaplan Center were designed as cast-in-place concrete tanks relying on a keyway and waterstop at the base of the tank in conjunction with a surface applied waterproofing coating for leak prevention.

Additionally, the base of these tanks occurs below the sublevel (basement) floor elevation in an area with a high existing water table. After completion and turnover of the project, it was observed that an ongoing water infiltration event was occurring in this basement level, with water entering the room through the joint between the floor slab and the concrete walls below grade. Through an extensive investigative effort, it was finally determined that the source of the water was a series of small leaks through the base of one of the surge tanks.

The plain white 60 MIL membrane was chosen and we could not be happier with the end result of the tank. In just a matter of two and a half days, our product eliminated their leaking problem with no issues, no heavy machinery, and no hassle. It was a pleasure to work with Skanska and Paddock Industries on this project, and we look forward to working with them on any future projects as well.

In the words of Steve Gourley, Project Manager for Skanska over the renovation, “The install was completed quickly, looks fantastic, and – most importantly – has eliminated any leaking from the tank. For any and all future projects in which a cast-in-place tank is designed, we will insist that this PVC liner be included in the specifications as a best-practice solution to leak prevention.”