Feature Article - November 2019
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The Air in There

Managing Air Quality in Aquatic Facilities

By Joe Bush


In Practice: University of North Texas

Chris Lawrence has firsthand knowledge on managing the relationship of water with air in aquatic facilities.

Lawrence is associate director of facilities at the 16-year-old Pohl Rec Center on the campus of the University of North Texas. The center has a 25-yard lap pool, shared with the UNT swim team, and an indoor leisure pool with a spa. Each enclosure has its own dehumidification system to control the heating and air conditioning.

Lawrence said the lap pool has had air quality issues, but only after the center had been open a few years. Complaints from athletes started coming in periodically, leading to air quality tests.

"They were looking specifically for chloramines," said Lawrence. "The tests indicated a slightly elevated amount, but nothing very substantial. It was determined at the time that it was not a significant enough problem to warrant a large expense."

The center added UV lamps as a secondary water treatment, and placed large fans aiming air up at the air returns and blowing across the deck which were used primarily during athletes' training times. Management's hope that this would help with what it saw as a minor issue was eroded by more and more complaints.

"Again, it was only the athletes that were experiencing any issue; however, this makes sense since they were the ones spending the longest amount of time in the pool and were in the water with the largest volume of swimmers exerting themselves," Lawrence said.

The UNT environmental safety office conducted a second air quality study, and it showed more significant chloramines present at peak athletics usage time. The school asked an aquatics facility consulting firm for an assessment, and it found that the location of the return on the HVAC to the dehumidification system was not ideal for pulling the chloramines, which sink and stay just at or above water level. The return on the HVAC was about 20 feet above the pool deck.

UNT had several choices, from refitting its air handling system to simply installing a fan over the lap pool.

The idea behind the fan was simple, said Lawrence: The chloramines create a bubble at the pool surface level, and the downward force of the air would, in theory, break the bubble forcing the air to the sides and back up, and hopefully to the HVAC.

"We opted for the fan, and had it installed a little over two years ago," he said. "Since its installation we have not had complaints about the air quality."

Lawrence said the problem and solution has taught him several things about aquatic water and air quality, but two stand out:


>>  The type of usage a pool will have is crucial in the design phase. Once pool systems are installed and things are built out, there are no easy or cheap solutions.

>>  The effects of bather loads.


A recreational lap swimmer at the Pohl Center spends an average of about 15 to 20 minutes in the pool. In busy times there is a load level of six to eight swimmers.

"It is quite a bit different for the swim team, which has 30 athletes going for two hours straight at a time and even more during meets," Lawrence said. "The impact on the air quality is significant between the two groups."

Lawrence is in a position to help others who have the same duties. Be prepared to spend a lot of time working through various challenges because despite the best planning, there will be hiccups, he said.

Operators should get to know the intricacies of their pools, said Lawrence—the usage type, user loads, the equipment like HVAC, water treatment chemical feeders and chemical monitoring systems.

"They all play a role in the end experience for the user," Lawrence said. "Each aquatics environment is unique and presents a unique challenge in producing a positive experience for the user."