Updated 5:29 p.m.
Workers began pumping chlorine into water below the rafting channel at the U.S. National Whitewater Center in Charlotte Wednesday, to remove an organism linked to a woman's death. Under a plan health officials approved this week, the treated water will be discharged into the Catawba River.
The Whitewater Center halted all whitewater kayaking and rafting in late June after tests found a common type of ameba that in rare instances is deadly. The tests came after the death of an 18-year-old Ohio woman, whose only known exposure to the organism was in the whitewater rafting channel.
The center is treating the water with a heavy dose of chlorine - a level of five parts per million. That will kill 99.99 percent of the amoeba and just about anything else living in the water, says Mecklenburg health department chief Marcus Plescia.
"That is 10 times what we believe is the concentration necessary to kill this particular organism or really any organism that might be living in there," Mecklenburg County health department director Marcus Plescia said at a press conference Wednesday morning. "This is going to be a real jolt into the water source."
Federal, state and local officials signed off on the plan during a conference call Monday. That followed weeks of review by the state Department of Environmental Quality, Mecklenburg County Health Department, the U.S. Centers for Disease Control and other local officials. The Catawba Riverkeeper and the Sierra Club also were involved.
Catawba Riverkeeper Sam Perkins said he supports the plan. "The final plan, if monitored and executed properly, is a good and reasonable solution to treat and discharge water containing the ameba (N. fowleri)," he said in a statement Wednesday afternoon. He said the plan means the whitewater center will be held to standards similar to those at wastewater treatment plants.
Rusty Rozzelle, the county's water quality program manager, said once the chlorine does its job, the water will be treated again with a second chemical, sodium thiosulfate, to remove the chlorine. The water then will be discharged into a wetland just north of the center. From there it will flow through the soil and wetland, into Long Creek, then into the Catawba River.
Rozzelle said it would take a minimum of seven hours to treat and discharge the 6.3 million gallons of water in the Whitewater Center basin. Once discharged, it could take hours or days to reach Lake Wylie, which is just downstream from the center, he said.
He said the treated water would be so diluted it wouldn't affect water quality in the river or in Lake Wylie. The center's pond holds 6.3 million gallons of water, just a fraction of the 93 billion to 100 billion gallons in the lake.
The water supply intake for the city of Belmont is just downstream. Plescia noted that the treated water not only would be diluted, but also treated again before it's sent into the water supply.
Plescia said the process for draining the basin is similar to what the whitewater center does annually. "This is a process they've done every year. It's not new," he said.
In a statement Wednesday afternoon, the Whitewater Center said it expects the process to take about 24 hours.
The chlorine also will treat sediment at the bottom of the center's pond, where ameba also are found. After the water is discharged, sediment also will be removed, and spread over an upland area at the center, Plescia said.
The ameba is naturally occurring, and isn't usually a problem, unless it gets up your nose. If that happens, it can cause a deadly brain infection. Health officials say there are only a handful of cases nationwide every year.
Plescia said about 6.3 million gallons of water will flow into the river.
"We really feel good about this and I know this kind of thing raises anxiety," Plescia said. "But I want people to understand we're really tried to put multiple components in this to make sure people can feel secure about this and feel that there's not any danger to public health, or to the environment."ukh said.
The county still has to approve a new treatment and monitoring systems for the channel, to ensure ameba don't become a problem again, Plescia said.
The man-made whitewater channel has been closed for a month, but the rest of the outdoor center remains open.
The center said in its statement it hopes to resume rafting and kayaking soon after the water is discharged:
"The timeline for reopening whitewater activities is still being determined, but we anticipate resuming whitewater operations shortly after completion of this process. We know that many of our guests are eager to return to whitewater activities, and we are doing everything in our power to provide our guests the opportunity to get back on the water as soon as we can. We appreciate your patience and consideration throughout this process"