Charlotte's Whitewater Center

Contractors, Designer Ride the Rapids into the Unknown

by Bea Quirk, ENR.com
08/2006

The world's first self-contained artificial river became operational last month in Charlotte. To create the $32 million U.S. National Whitewater Center, two Charlotte firms, Liquid Design and RodgersDooley, utilized technology from around the globe, as well as their own innovative thinking.

It's surprising, even for longtime residents, to realize that just 10 minutes from downtown Charlotte's office buildings, condo towers and hustling crowds, the Catawba River flows through a forested landscape with only a few scattered homes.

But now something has been created in this rural pocket that has attracted the attention of people from around the globe: the world's first multiple-channel artificial river using a closed-loop system, which went operational in July.

Visitors to the $32 million U.S. National Whitewater Center - from Olympic-caliber kayakers to folks just wanting a casual fun rafting experience - will be able to ride the rapids on a curving up-and-down course starting at an upper pool and rafting down a channel that drops 21 ft. to a lower finishing pool.

With the water flowing at 800-900 cu. ft. per second, and boulders carefully placed to recreate the rapids of a natural rocky stream, the rafters should get their share of thrills during the typical 1.5-hour experience.

When they're done, they can jump onto a conveyor belt system to return to the top of the course and repeat the experience. The 4,000-lin.-ft.-long artificial river, which is on 50 acres, is also being used as a training facility for competitive kayakers and as a site for competitive events.

There are other, similar manmade facilities - the most notable one is in Sydney, Australia, which was used for the 2000 Olympics. But in those, the water is supplied by an adjacent river. Even though the Charlotte facility is also located on a river, it doesn't draw water from it, making the system self-contained.

"We had to deal with several jurisdictions, and the red tape was so hard to overcome, it could have taken us years to get all the authorizations (to draw from the river)," said Michael Williams, president of Liquid Design, the Charlotte architectural/ construction management company that designed and managed the project. "It made more sense to create our own pond, and it was more cost-effective to keep using the same water."

The 12 million - 14 million gallons of water needed to fill the artificial river comes from the Charlotte Mecklenburg Utilities Department, which had an existing pumping station near the new facility. To ensure efficiency, the center built another station, as well as a 2,000-ft.-long line, so it is directly connected to the CMUD system.

The actual sitework began in March 2005, but the design work began about two years earlier. The general contractor, Charlotte-based RodgersDooley, was involved from the start, as was consultant Scott Shipley, an Olympic kayaker who also is a mechanical engineer.

"He dealt with the water and made sure it does what it's supposed to do," said Williams, who was the project's lead designer. RodgersDooley is an alliance between Rodgers Builders and RT Dooley, both of Charlotte. Liquid Design and RodgersDooley are also creating the conference center/restaurant and the climbing center, which are being completed this summer.

The nonprofit facility also includes indoor and outdoor climbing areas, a ropes course, 11 mi. of trails and a 20,000-sq.-ft. conference center/ restaurant. The center is located on Mecklenburg County's 300-acre Historic Tuckaseegee Ford District Park near the intersection of interstates 85 and 485. The trails - for walking, hiking, jogging and mountain biking - were in place before the center was established.

Monies have been raised from the private sector and will also come from the proceeds of operating the center. There has been no direct government funding, but Mecklenburg County and several neighboring towns have guaranteed the loans.

"It (the artificial river) was unusual, and no one knew how to build one, and no one knew what it would cost," said Scott Carr, Rodgers' senior project manager. "There were so many unknowns, and we had to convince the building inspectors it was safe."

That was especially true when all they had was a concept. "We all did lots of research, and evaluating systems became an art," Carr added. "We went through tons of schematics. It became all about working together as a close-knit team. This has been awesome and a lot of fun, one of the best projects I've worked on. I'd love to start another one tomorrow."

Jeff Wise, the center's executive director, said it was important to the team to build a facility that was known for aesthetics, durability and functionality, as well as something that was user-friendly for both novices and world-class athletes. "That was a tall order," he added. "But the design and construction team has given us everything we asked for."

Going into the unknown offered a variety of challenges. Pumping and filtering the water was a major concern. The pump system is made up of seven submergible pumps made by ITT Flygt of Sweden.

The system, which Williams said is the largest ever assembled for a whitewater park, cost $1.2 million and is capable of pumping 536,000 gallons per minute. That's fast enough to fill an Olympic-sized swimming pool in nine seconds.

A filtration system supplied by PEP Filters of Israel will purify the water through ultraviolet treatment instead of traditional chlorine. The price tag was another $1 million.

Because of the fast-track construction schedule, a plan was devised to prevent possible rain delays. As soon as portions of the channel were dug and a liner installed, the concrete was poured to a 6- to 8-in. thickness.

"They chased each other around the course," Carr said. Concrete pouring began last August and was completed in June.

Instead of shotcrete, traditional cast-in-place concrete was used. To improve the water's flow, the concrete needed to be as smooth as possible. To finish the concrete, Rodgers staffer Mark Cassel designed a jig that was attached to the fork lift that smoothed the concrete out after it was poured. It was dubbed 'The Castle' in his honor.

Altogether, RodgersDooley laid about 15,000 yds. of concrete. The center was spared the recent dramatic increase in the cost of concrete because the company locked in the price about two years ago.

To minimize the potential for damage to the welded liner under the concrete and decrease the amount of concrete cracking, RodgersDooley used a fiber additive instead of wire mesh in the concrete. Vents were added to help relieve pressure on the concrete, especially in the lower pool.

Still, Carr conceded there will be water loss - up to 100,000 gallons a day - from leakage, splashing, filter backwash and evaporation.

Jeff Gustin, vice president of Liquid Design, acted as senior project manager for the artificial river and coordinated the work of 24 subcontractors, who had as many as 200 workers onsite at one time.

Those subs had to be convinced they could do the work because "it wasn't the typical job they did every day," Carr said. "But we broke the work down and showed them they could do it cost-effectively and quickly."

RodgersDooley took responsibility for erosion-control monitoring of the site instead of handing it off to the site coordinator. The center sits on the Catawba's dirtiest tributary, Long Creek, where runoff is a major problem.

"This was just too important to us," Carr said. To prevent further damage to the river from construction, Rodgers personnel took classes on erosion control and used double-silt fences and multibaffled erosion control ponds on the site.

Despite its name, Liquid Design had no previous whitewater park experience. (Liquid refers to the company's flexibility, Williams said.)

But Williams added that he is now eager to use what he learned. "Charlotte won't be the last of these super parks, and now that we have figured out the technology, we can put one in anyone's backyard," he said.