Clearing the Air
Grapevine-Colleyville Swim Center
By Roger Lisenbey
Poor air quality had long plagued the indoor Grapevine-Colleyville Swim Center in Grapevine, Texas, causing severe discomfort for competitors and spectators alike and resulting in the facility being routinely shut out of hosting major swim meets. For many years, the center waged a losing battle brought on by problems associated with undesirable chlorine by-products. The center, training ground for the highly-ranked Grapevine High School and Colleyville Heritage High School swim teams, suffered from high levels of chloramines in its indoor 333,000-gallon, 10-lane pool, which caused irritated eyes, skin and sinuses, and foul-smelling air inside the facility.
The 25-yard by 25-meter competitive pool, built in 1994, is used by 600 to 800 swimmers every day from the Caroll, Grapevine-Colleyville and Northwest school districts, located just outside of Dallas. The center recently completed a $2.5 million renovation that added additional bleachers, offices, classrooms and weight rooms. Long before renovations began, center management had been struggling to find a permanent solution to chlorine-based odors and corrosion.
An overwhelming chlorine smell had plagued the center since it opened. Initially, bromine was used for water sanitation in the pool, but center staff found the chemical sanitizer could not keep up with bather loads. A switch to calcium hypochlorite improved water quality and clarity, but air-quality problems associated with undesirable by-products of chlorine persisted.
"Air quality was so poor that during workouts our swimmers had to walk outside for fresh air," says Swim Center Director and Swimming World magazine's Coach of the Year, Patrick Henry. "In fact, our own athletic director could only stay in the pool area for 10 to 15 minutes at a time."
High combined chlorine levels (1.0 to 1.5 ppm) in the pool water was the source of the problem, and fluctuating bather loadings made it difficult to maintain balanced water chemistry in the pool.
"When you walked out on deck in the morning, within three steps beyond the door you knew what kind of day it was going to be air quality-wise: bad or real bad," Henry says. "And I'm probably as much or more immune to chlorine irritation than many people because I've been around it for so long—being a competitive swimmer and being a competitive swim coach for almost 20 years. But this was very intense. Lifeguards at times could not perform a rotation because their eyes were watering badly. Parents came in and sat in the bleachers for a few minutes and then had to leave and sit out in the lobby because they could not handle the chloramines in the air."
Center management took a number of steps to try to alleviate the problem, including a regimen of shocking the pool (superchlorination) as well as increasing air flow inside the facility in an attempt to dilute the bad air. During the center's hours of operation of 6 a.m. to 9 p.m., the double doors leading to the outside remained open and fans blew air straight out, causing excessive energy consumption. Despite these efforts, air quality inside the facility remained poor.
Herman Vaughn, maintenance manager for the center, sums up the problem as one of ultra-wide swings in water chemistry.
"Pool water chemistry always seemed to be either just right or in real bad shape and needed to be shocked immediately," he says. "There really never seemed to be any middle ground between those two conditions."
Even the dehumidification system's condensate displayed high levels of combined chlorine (0.2 ppm). Continued chloramine-saturated air was translating into shortened equipment life and higher maintenance inside the center due to corrosion of pool and facility hardware.
"High corrosion rates, due to the high chloramines in the air, demanded a lot of work," Vaughn says. "Our stainless-steel components were rusting and had to be cleaned daily. Even the metal frames that hold the filters for our air handling system were corroding out."
Another casualty brought about by the poor air quality was that the center was routinely shut out of hosting major swim meets. Teams training at the facility had won three state team championships in the past four years, and Grapevine, Coach Henry's team, was ranked the No. 2 high-school team in 1998. And even though the center ran its swim meets in 10 lanes (rather than in six or eight lanes) and was an attractive, new facility, it hosted no meets the first year it was open, due to the poor air quality inside the facility.
On the advice of Aqua-Rec, a member of the International Recreational Water Professionals (IRWP), the center decided to take a different approach. However, it took some serious convincing before the change was made.
In all pool environments, swimmers bring organic-based nitrogen substances to the water, and these contain complex substances that release by-products into the water as they oxidize. These by-products impose a demand on chlorine. Conventional chlorine control systems typically respond slowly to sudden changes in demand, bringing about under- or over-chlorination and prompting the formation of chloramines that can bring poor air quality in indoor pool environments. The IRWP representative proposed the installation of a new automated system from USFilter Stranco Products (in Bradley, Ill.), the Strantrol Environmental Control System (ECS), which is designed to provide precise control for pool water chemistry, thereby bringing optimum air quality to indoor aquatic facilities.
"When the ECS system was first proposed, I thought no way," Henry says. "For one thing, it sounded too good to be true. Also, we would be the first facility in Texas to install this new technology, which made me that much more apprehensive."
The water balance was optimized at startup of the new system, and within a week and a half of operating (and after years of almost never experiencing chloramine-free air), the Grapeville-Colleyville Swim Center's air-quality problems were solved.
The new system controls the rate of oxidation and also the types of oxidation reactions that take place in pool water. In doing so, the system is designed to feed the optimum concentration of oxidizer in order to prevent the formation of volatile chloramines. This is accomplished utilizing High Resolution Redox (HRR) technology, which directly and continuously measures the rate of oxidative disinfection that can be affected by organic load.
The system also calculates the Ryznar Index, which indicates the corrosive tendencies of the water and computes the required chemical addition needed to properly balance pool water. The benefits of maintaining the proper Ryznar Index include reduced maintenance costs associated with extending equipment life, cleaning pool surfaces and resurfacing of the pool.
In addition, combined chlorine levels in the dehumidification system's condensate are now undetectable, translating to less problems with corrosion. The new system consistently maintains combined chlorine levels in the pool water at <0.4 ppm. The improvement in water and air quality has eliminated the need for superchlorination.
Now that the air has cleared, Henry says the Grapevine-Colleyville Swim Center is getting the respect it deserves as a first-class site for regional swim meets.
"We bid to host seven meets in 2000 and were awarded all seven, we had no opposition," he says. "We're now running great meets here."
Since the ECS system was installed, the water chemistry in the pool has remained in proper balance. The formation of volatile chloramines is now being prevented due to the optimized and controlled rate of oxidation of all organic nitrogen compounds that enter the pool. Continuously clean air is now standard at the facility, and according to Vaughn, chloramine levels in the pool water typically run less than 0.6 ppm. The water is also much more clear and bright, and problems with corrosion due to high chloramine levels in the air have ceased.
Henry says that one of the biggest benefits of clearing the air is that the facility is now a better place to train.
"We have kids here that train at very high levels, and many were having breathing problems due to chloramine-saturated air," he says. "By optimizing the balance of our pool's water chemistry, air-quality problems are no longer getting in the way of training."
Roger Lisenbey is president of Aqua-Rec, Inc. in Azle, Texas, and a member of International Recreational Water Professionals (IRWP).
For more information
USFilter Stranco Products: 800-809-0971