The Water Resources Department has continued to outline the progress made in restoring potable water to the thousands of locals and businesses left without after the storm, sharing updates on treating the North Fork reservoir and keeping the public up to date on the water system in Asheville.
Typically, the City of Asheville has not provided an exact timeline for complete restoration and treatment, still stressing that “water restoration will occur slowly and incrementally.”
However, in the Friday, Nov. 15 community briefing, Water Resources Department PIO Clay Chandler delivered some unexpected (but extremely welcome) news — potable water could be restored as early as Wednesday, Nov. 20.
If you’ve been following the water updates, you can certainly skip ahead, but in case you need a refresher, here’s a little background.
The background
Asheville is served by three water treatment plants — North Fork in Black Mountain, Mills River near the airport, and William DeBruhl in Swannanoa — which together operate thousands of miles of pipes.
The Mills River plant, which primarily serves South Asheville, is fully operational. The city is asking those with water to conserve, and the boil water advisory remains in effect. The William DeBruhl plant (usually referred to as Bee Tree) had waterlines demolished in the storm and is currently inaccessible until roads are repaired. According to the county, a lot of debris has been removed and road repair is beginning — but a debris removal plan is still ongoing, as of Friday, Nov. 15.
North Fork, the principal water treatment plant for the area, is responsible for 80% of our water. North Fork’s 36-in bypass waterline experienced significant damage after the storm washed away almost 25 feet of ground. This bypass line was a redundant installation meant to mitigate any damage to the 36-in and 24-in main and transmission lines and was originally built to withstand a typical hurricane event — but Helene exceeded the typical. With these other lines gone, repair of the bypass line became a top priority.
Helene shifted the waterway entirely and it now flows over the lines, so crews had to construct dams as they went to make the repairs. The crew also had to run the repaired line further than the original because the original line was clogged by boulders.
The rebuild, which was installed deeper and is armored, has been reconnected. On Wednesday, Nov. 6, T&K Utilities finished installing the 24-inch and 34-inch primary transmission lines — and all lines, including the 36-inch bypass, are now in service. At an early news briefing, Assistant City Manager Ben Woody shared some context for the speed of those repairs: When the bypass line was originally installed, it was a three-year project. If they were operating under normal conditions to do these repairs, the installation of the bypass line alone would be a two-year project.
To address the turbidity (amount of sediment) of the water in the North Fork reservoir, the local team and the EPA created a pilot plant (which is a small version of the plant, kind of like a lab) to test treatment options and developed an in-reservoir treatment plant. These measures are meant to address the turbidity of the water and allow for coagulation, which removes the charge from the particles in the water and allows them to settle.
Pipes, reservoir treatment, and turbidity curtains
On Thursday, Oct. 10, water resources staff began pressurizing and filling the North Fork Bypass line. Restoration began in Swannanoa — which Woody called “ground zero” of the water system destruction — and started moving incrementally west from North Fork to Asheville. Nearly all of City of Asheville water service has been restored, but the water is still nonpotable.
On Tuesday, Oct. 15, large batches of aluminum sulfate and caustic soda arrived at the North Fork reservoir to begin a first round of treatment. These chemicals aid coagulation and PH balance, respectively. Note: These materials are used by the Water Resources Department as part of their normal treatment process.
As a reminder, coagulation is the process of reducing the electric charge of the particles in the water so that they can gravitate toward each other, become heavier, and sink to the bottom. This process is ongoing.
Even after treatment began, crews continued to pressurize and fill the system with this sediment-heavy water, which allowed them to repair smaller leaks, fill tanks, remove airlocks, and flush the system without waiting for the reservoir treatment to be completed — thus speeding up restoration of service.
The treatment plan had other pieces, though. The long-awaited turbidity curtain — which works as a shield to block sediment from flowing into other application zones of the water and to allow water treatment to be completed in stages, rather than having to treat the whole reservoir at once — was anchored in place on Wednesday, Oct. 30. A mama bear and cub showed up to supervise, and Chandler noted that they seemed pleased, “I hope we can share some good news with them.”
The second round of treatment, then later a third, was able to begin after the curtain was installed.
The target turbidity level changes
A brief interlude for a definition. Turbidity, which is the cloudiness of water caused by suspended particles, is measured in Nephelometric Turbidity units (NTUs). The Water Resources Department was initially aiming for 1.5-2 NTUs before putting potable water back into the system. To get a measurement of current levels, crews record the maximum turbidity over a 24-hour period.
As of Friday, Nov. 15, the North Fork reservoir’s turbidity was sitting at 15.5 NTUs — but the target levels have changed. And crews have already been pushing potable water into the system.
PIO Clay Chandler clarified that tests were conducted with the on-site pilot plant to see how the filters would handle the turbid water and what maintenance would look like, and staff concluded that it would be possible to run the still-turbid water through the filters without damaging them.
A faster-than-expected restoration timeline
The amount of treated water that crews have been able to push through the system has slowly increased, and the increase led to an unexpected announcement at the Friday, Nov. 15 briefing. According to Chandler, the boil water notice might be lifted as early as the night of Tuesday, Nov. 19.
We’ve been wanting to type “the boil water notice lifted” for more than a month now. But this news was a little out of the blue, so let’s dive in to the details of this new timeline.
As of Friday, ~25 million gallons of treated water were being pushed through the system — and that’s the amount needed to keep the system pressurized. No raw water has been used in the system since Saturday, Nov. 9, which means there has been only treated water in the pipes for about a week. Even further, the mechanism for pushing raw water into the system was taken offline the night of Friday, Nov. 15.
“The use of treated water combined with customer usage has given us data that we feel is sufficient to reach the conclusion that the system has, for the most part, turned over,” said Chandler. “And the vast majority of raw water has been replaced with treated water. Because of this, we are at the point that we can begin the sampling process to potentially lift the boil water notice.”
The plan for potable water
In order to lift the boil water notice, the Water Resources Department has to take 120 water samples in various locations for testing. This sampling process, which was developed in conjunction with the EPA and the NC Department of Environmental Quality, should wrap up late on Monday, Nov. 18, then the samples have an incubation period of 18-24 hours. After the incubation period, the department will be able to assess the health of the distribution system and know whether it is safe to lift the boil water notice.
This may seem quick, given that the city had said a 2-3 week flushing process would be necessary after treatment was back online. But Chandler clarified that this flushing process had, in effect, been happening since Oct. 30, albeit much more slowly than the normal process would be. Instructions will be provided to customers when the boil water notice is officially lifted, but the private flushing process has also been happening just through normal usage.
If testing shows that the water isn’t yet safe for consumption, the boil water notice will remain in place — but resampling will be done almost immediately.
The lifting of the notice will indicate that your water is safe for consumption, and restaurants and businesses can operate unrestricted. But as of right now, the boil water notice is still in effect. And Chandler also noted that if turbidity levels increased after the boil water notice was lifted, it might need to be reinstated.
Let’s talk lead
On Thursday, Nov. 14, news broke that seven area schools had tested positive for detectable lead in their water. Chandler stated that students had not consumed the water and that the source was older pipes. Because of the piping configuration at the North Fork Water Treatment Plant, Water Resources was unable to treat the raw reservoir water with zinc orthophosphate — which provides corrosion control — for ~19 days.
At the Nov. 15 briefing, Chandler further confirmed that tests of the source water had come back negative for any detectable lead. There was a trace amount of copper detected, but it was “way, way below the action limit.”
According to city officials, “Plumbing in structures built before 1988 have increased potential to be a source of lead exposure if water sits undisturbed in plumbing for 4-6 hours.” So even when the boil water notice is lifted, Chandler said that structures built before 1988 will need to follow a flushing protocol to drastically reduce any potential detectable lead in their water.
Residents in homes built before 1988 are encouraged to request a lead and copper testing kit by contacting Water Resources at 828-259-5962 or emailing leadprevention@ashevillenc.gov.
USACE’s backup plan is still ongoing
The mobile treatment unit project started by the US Army Corps of Engineers (USACE) as a backup plan is still ongoing — and even if it isn’t necessary to lift the boil water notice, it will be in place as a redundancy. Chandler said that they hope to be able to keep the system until our filters are upgraded to be able to handle more-turbid water.
The 12-13 units, situated above the dam, will be able to treat 25 million gallons per day, which would be enough to keep the system pressurized.
In a very simplified way, these mobile treatment units contain sedimentation plates that are able to remove almost 100% of the sediment in the water. They take the water out of the reservoir, get its turbidity down to 1-2 NTUs, then plug it back into our treatment system. Crews are still working 24 hours a day until the system is operational.
This project is expected to be operational by very late November or very early December.
