I’ve joked for weeks now that I’m going to sell my own T-shirts in Asheville that read: “Today’s mood: Turbid.”

It’s fair to say “turbidity” is probably the word of the year in these parts. OK, maybe it’s just behind “Helene,” but that is a name that must not be spoken aloud.

When the mountains got a thorough soaking on Sept. 25, in a system preceding Helene, folks were getting a little nervous around here, partly because it takes only about 5 inches of rain to create landslides and flooding. (Ten days before Helene, Asheville Watchdog published a story about Asheville’s increased risk of flooding.)

In 2004, back-to-back remnants from hurricanes Frances and Ivan wreaked havoc on Asheville’s main water supply, the North Fork Reservoir, stripping away the two main transmission lines and leaving customers without service for nearly two weeks.

The city installed a separate bypass line afterward, one capable of delivering water from the reservoir near Black Mountain to customers in Asheville. A 350-acre lake nestled in a 20,000-acre watershed, North Fork provides 80 percent of Asheville’s drinking water.

That 25-foot deep bypass line was no match for Helene when it rolled into the area in the wee hours of Sept. 27.

The city announced Sept. 29 that the storm “severely damaged the production and distribution system of the City of Asheville’s water system.”

“Extensive repairs are required to treatment facilities, underground and aboveground water pipes, and to roads that have washed away which are preventing water personnel from accessing parts of the system,” the announcement said. “Although providing a precise timeline is impossible, it is important to note that restoring service to the full system could potentially take weeks.”

In an interview the next morning, Asheville Mayor Esther Manheimer told me the damage was similar to what occurred in 2004 and was exacerbated by a washed-out road leading to the reservoir.

“What we’re communicating to people is, plan for (the) long-term — we’re talking weeks, not days,” Manheimer said of potential outage time. “We want people to plan for that. Hopefully it won’t be that long.”

It was that long. 

The city had to replace the two main transmission lines, 24 and 36 inches in diameter, and the 36-inch auxiliary transmission pipe the city had installed in a different location from the main lines after the 2004 outage. 

The city hired multiple contractors who worked around the clock to dig out and replace the two washed-out main transmission pipelines, and the bypass line. They also had to fix the road that leads to North Fork.

Water Resources spokesperson Clay Chandler and Assistant City Manager Ben Woody offered frequent updates throughout the fall, and the photos and videos they aired during the daily briefings told the story: The transmission lines, along with roads and distribution lines, were annihilated. In some cases, workers couldn’t even find the old pipes.

That 25-foot deep bypass line built following the 2004 outage was “engineered and installed to withstand a 2004 event, without a doubt,” according to Woody.

It turns out Helene brought us a 1,000-year rainfall event, though, and 2004 was child’s play comparatively. It also turns out that the city showed vision in completing a major spillway upgrade at North Fork in 2021 that may have prevented the dam from giving way and inundating the Swannanoa Valley and Asheville with a catastrophic cascade.

Non-potable water returned by mid-October

Honestly, after viewing Helene’s power in so many areas, particularly Swannanoa, I’d say it’s a minor miracle that the restoration crews, which included plenty of Water Resources workers, were able to get pipes back in place and restore at least non-potable water by the middle of October. The city opted to replace the bypass transmission line first, and that got the system wet with unfiltered but highly chlorinated lake water.

It was a start, and it at least allowed people to flush commodes and take showers (if they were a little adventurous). 

The city’s Bee Tree Reservoir in Swannanoa also sustained heavy damage from Helene, and high turbidity has kept it out of operation all year. 

The city’s third drinking water installation, the treatment plant on the Mills River in northern Henderson County, remained operational throughout the crisis, but it’s not able to produce enough water on its own to meet the demand of the city’s 63,000 water customers.

The city steadfastly refused to give any specific timeline on restoring potable water, sticking to the “weeks” estimate. Meanwhile, a boil water notice remained in effect as the city tried to reduce turbidity in North Fork with multiple treatments of chemicals that enhance coagulation, and the installation of “turbidity curtains,” which help still the water in front of the intakes to the treatment system.

Meanwhile, the city had been working with the U.S. Army Corps of Engineers, which had assembled a small pilot plant at North Fork to determine just how much turbidity the reservoir’s direct filtration system could handle. 

This brings us to another term we’ve all come to know and love: Nephelometric Turbidity Units, or NTUs.

This is how turbidity, or water murkiness, is measured. Normally, North Fork’s untreated water is around 1.0 NTUs, but it had soared to 79 after Helene.

Water Resources maintained turbidity would have to drop to 1.5 to 2.0 NTUs for North Fork to be able to treat the water. But it turned out the Corps’ pilot plant directly filtered water, the same way the reservoir does.

The Corps and the city discovered that as the muddiness cleared, it could indeed filter higher-turbidity water, in the 10-12 NTUs range. By early-to-mid November, North Fork was pushing out 17 million gallons of treated water, then 20 million and even more.

The city was on the path to restoration of potable water.

The lead issue, and the return to potable water

But on Nov. 14, it dropped a bombshell: Its testing had detected lead in seven schools, after Asheville water didn’t undergo the normal lead mitigation process for nearly three weeks.

The city’s use of the bypass line for water transmission did not allow for the water to pass through the regular treatment process for 19 days. That regular process involves adding zinc orthophosphate and sodium bicarbonate, minerals that coat the insides of pipes, with the zinc material absorbing the lead and keeping it from reacting with the water. The bicarbonate controls pH.

The city re-established corrosion control treatment Oct. 30, but it can take 30 to 90 days for the chemicals to fully work.

While health officials and the city said no students had consumed the water, and flushing pipes typically removes any lead that may have leached into the water, customers were understandably concerned. Within a month, the city had been inundated with requests for lead testing kids, more than 8,000 by mid-December.

The lead issues took some of the shine off of the city’s announcement Nov. 18 that it had restored potable water, and that the EPA said the water is safe to drink. As Asheville Watchdog previously reported, two outside experts expressed concern about the lead, as no level is safe in drinking water, and they urged customers in houses built in 1988 or before, when lead rules changed, to get the testing done before consuming water.

A mobile filtration system, possible improvements in the future

Meanwhile, the Corps of Engineers were working on another project, which Chandler, the Water Resources spokesperson, had announced in October, to bring in a mobile filtration system at North Fork designed to work on high-turbidity water. The Corps spearheaded the project, awarding a six-month, $39 million contract to Ahtna/CDM Smith on Nov. 8. The contract has an option to be extended.

The mobile filtration system became partly operational in early December, and Chandler said Dec. 18 that three of 13 units were operational. Eventually it “will do most of the heavy lifting, with North Fork’s existing processes providing support, to produce the average daily demand of 20-25 million gallons of water,” Chandler had said previously.

On another positive note, the initial batch of lead test results came back in early December, with favorable results. Results for 159 homes showed nine had detectable levels of lead “on the first draw,” Chandler said at the Dec. 9 briefing. 

“First draw” means water has sat in the customer’s pipes for at least six hours and a sample is taken without first flushing.

“Of those nine, only three were either at or exceeded the action level of .015 parts per million,” Chandler said then. “Here is the most important part: After flushing for 30 seconds, out of 159 samples taken, zero had detectable levels of lead.”

The news improved Dec. 18 when Chandler noted 305 more tests had come back. 

“Out of 464 results that we’ve gotten back so far, 19 had detectable levels of lead on the first draw,” Chandler said. “Of those 19, eight were over the (EPA) action limit of .015 parts per billion.”

Out of 464 flush samples, where customers let the water run for 30 seconds, two have had  “very slight detectable levels of lead in them,” Chandler said, noting that one could be the result of the customer mixing up test bottles and the other was in a basement sink where the water had not run in weeks.

And that’s where the system is today — with potable water but officials still urging customers in older homes to let the water flush for at least 30 seconds before consuming it, or until the water temperature changes.

It’s been a long arduous process to bring the water back, and Woody said previously the city is going to have to consider some more system improvements to prevent another long-term outage. Those include a primary water transmission line from North Fork that routes in a different direction than the others — and is not in the path of the spillway.

The city also will have to look at a permanent filtration improvement to North Fork, which could cost in the neighborhood of $100 million. The city already has in its capital improvements plan provisions for upgrading the Mills River treatment facility to increase its capacity.

North Fork typically produces about 21.5 million gallons of water a day, Mills River about 3 million. The city also likely will explore another water source somewhere on the western side of Buncombe County, Woody has said.

Clearly, this outage has been a learning experience for the city, and as I’ve noted before, Water Resources did not have a good handle on just how turbid North Fork water could be and still be treated.

But this was truly an unprecedented event — one that caused flooding that eclipsed the previous benchmark flood of 1916. It claimed 43 lives in Buncombe alone, and more than 100 throughout the region, and it caused billions of dollars of losses in property damage.

Put in that context, restoring potable water in under eight weeks was a remarkable accomplishment, albeit not one without some hiccups along the way. 

Asheville Watchdog is a nonprofit news team producing stories that matter to Asheville and Buncombe County. John Boyle has been covering Asheville and surrounding communities since the 20th century. You can reach him at (828) 337-0941, or via email at jboyle@avlwatchdog.org. The Watchdog’s local reporting during this crisis is made possible by donations from the community. To show your support for this vital public service go to avlwatchdog.org/support-our-publication/.

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