One year after Helene, Asheville’s water system remains ‘very, very vulnerable’

One year after Tropical Storm Helene left Asheville without potable water for nearly two months, the city’s water system remains defenseless against the disruptive powers of a much lesser storm.

Since Helene, the city has taken numerous steps to secure the system, including rebuilding and burying a key auxiliary line deeper than its previous depth and hard-packing earth around it to armor it. It also partnered with the U.S. Army Corps of Engineers to hire a contractor to provide a filtration system at North Fork Reservoir that can handle high-turbidity water, with an initial price tag of $39 million for six months.

But that system and a pre-treatment system at the city’s other reservoir, Bee Tree, are funded by FEMA only through the end of the month, and the cost to operate them is roughly $6 million per month. If FEMA doesn’t fund the systems beyond then, they may be demobilized and taken off site.

And longer-range plans to shore up the resiliency of the water system, which has a history of outages and other delivery problems, will take years and tens of millions of dollars to come to fruition.

In an August presentation to Asheville’s Council of Independent Business Owners, Asheville Water Resources Department spokesperson Clay Chandler said if the water department had to shut down existing systems to prevent filter damage, the contracted systems in place at North Fork and the city’s other reservoir, Bee Tree, would have to meet 100 percent of demand.

“If the pre-treatment systems were not available, 80 percent of the water system, or essentially everything north of the Blue Ridge Parkway, would begin to lose service,” the August presentation stated. “Within 24 hours, North Fork would be able to send highly chlorinated raw water into the system, necessitating a Boil Water Notice.”

And at the final community briefing for Helene on Sept. 3, Chandler described the water system as “very, very vulnerable.” 

“It would not take an event the intensity of Helene to put our treatment and filtration systems at risk, and that is like the top-line point we have made to our federal partners the last several months,” Chandler said. “We are back together, but we are very vulnerable.”

Helene along with a precursor storm two days earlier dumped 17.51 inches of rainfall on North Fork’s 20,000-acre watershed from Sept. 25-27, 2024. Both the Swannanoa and French Broad rivers set flood records, cresting at 26.1 feet and just under 25 feet, respectively.

At North Fork, which contains about 6 billion gallons of water and provides 80 percent of the system’s fresh water to the city’s customers, the excessive rainfall packed a wallop. It washed out the two main transmission pipelines that followed a roadway beneath the reservoir’s earthen dam, as well as an auxiliary bypass line. The flood also dislodged miles of distribution lines that follow the Swannanoa River.

Complicating restoration, North Fork turned a muddy brown, caused by heavy turbidity that left Asheville’s water undrinkable for nearly two months.

Chandler has said the city would like to keep the filtration systems in place “until a permanent treatment solution is built and operational at both North Fork and Bee Tree,” the city’s other reservoir, which is located in Swannanoa. 

“We know the temporary pre-treatment systems will remain in place at North Fork and DeBruhl (at the Bee Tree Reservoir) through the end of September,” Chandler said. “We continue to negotiate with FEMA to keep them in place as long as possible. Currently, we do not have a commitment from FEMA to fund the systems beyond the end of September.”

Additionally, the city installed “turbidity curtains” at North Fork, located outside of Black Mountain in eastern Buncombe County, to help settle the water and reduce murkiness. The city owns the curtains, so they will remain in place.

In 2004, North Fork’s two main transmission lines also washed out, leaving the city without water for about a week. After that storm, the city replaced the two main transmission lines, 24 and 36 inches in diameter, and it added an auxiliary 36-inch transmission pipe in a different location from the main lines.

Contractors buried that auxiliary line 25 feet deep. Last October, Assistant City Manager Ben Woody noted that the auxiliary line “was engineered and installed to withstand a 2004 event, without a doubt.”

But it was no match for Helene, washing out with the other two lines on Sept. 27.

Last fall, when contractors replaced it, they buried it 40 feet deep.

Longer-range plans will take years, cost tens of millions

The city is working on several long-term steps to secure drinking water and make the system more resilient in the age of climate change, which delivers more intense and more frequent heavy rainfall events. 

“At the top of that list are permanent treatment solutions for our filters at North Fork and DeBruhl treatment facilities,” Chandler said. “Those are in the design phase as we speak.”

The reservoirs currently use a “direct filtration system” designed for relatively pure water, which both reservoirs typically delivered pre-Helene and do once again now that sediment has settled. But now, with hundreds if not thousands of downed trees in the watershed, runoff into the reservoirs is less pure, especially during heavy rainfall.

North Fork experienced a 15 percent tree canopy loss from Helene. Within the first year after the storm, the watershed was projected to experience 20 times the increase in sediment entering the reservoir, according to the CIBO presentation in August. That is expected to drop to a four-times increase the second year.

Bee Tree’s watershed saw a 35 percent canopy loss, creating 50 times the sediment entering the reservoir in the first year after Helene. The number should drop to nine times the second year, Chandler said.

Asheville Mayor Esther Manheimer said Sept. 23 via email that the “top of the priority list for resilience projects is permanent treatment systems at North Fork and DeBruhl (Bee Tree). In a perfect world, that and the alternate bypass proceed simultaneously,” referring to a planned additional line out of North Fork.

“If we started today on the permanent treatment systems at North Fork and DeBruhl, build-out would take between three and five years,” Manheimer said.

North Fork opened in 1955 and has a large, undeveloped watershed. Chandler said the watershed is not polluted with artificial debris or plastic or other pollutants, but it does “have a ton of debris” in it, nearly all downed trees, logs and other vegetation from Helene.

“But that still, during even moderate weather events, would put our treatment and filtration systems at risk,” Chandler said. “That’s the No. 1 thing we’re dealing with.”

The turbidity at North Fork has returned to pre-Helene clarity, but that could change with a significant rain event.

As a permanent filtration solution, the city would look to install sediment basins and plate settlers, Chandler said.

“The plate settlers allow greater settling in a shorter basin, which makes a smaller footprint possible,” he said. “The basins at North Fork and DeBruhl will need to be shorter due to the topographical restrictions we have to navigate at both plants.”

Other long-range projects include:

Adding the alternate bypass line running out of North Fork

“It is an additional bypass line that will be geographically separate from the current one and will, to the extent possible, avoid the run of the Swannanoa River,” Chandler said at the Sept. 3 briefing. He notes that details such as the diameter and exact route of the new bypass would be finalized during the project’s design phase.

“The alternate bypass would supplement the existing mains and the existing bypass,” Chandler said via email Sept. 24. “We are seeking FEMA Hazard Mitigation Grant Program funding for this project.”

Manheimer said the bypass line project will take years to complete.

“Timeline for alternate bypass is more difficult to estimate, because it depends on easement negotiations etc. It’s safe to say that project, even if we receive funding for it, will be measured in years,” Manheimer said.

The 2004 bypass cost $2.5 million to install, and the city got an estimate for an alternative bypass in 2014 that came in above $12 million, Manheimer said. That cost has escalated considerably since then, as a new bypass would involve miles of line and a lot of land acquisition.

“For context, the alternative bypass that we’re seeking design funding for now, with easements, right-of-way costs etc, could exceed $60 million,” Manheimer said. “Nothing associated with a water system happens quickly or comes cheap. That’s the reality we live in.”

Expansion of capacity at the Mills River plant

On May 23, city officials and water department workers gathered at the Mills River plant to celebrate the launch of the “Mills River phase 2 plant rehabilitation.”

The project will increase the plant’s off-stream raw water storage from the Mills River and will update valves, filters and other equipment in the plant. The project will expand the plant’s treatment capacity from 7.5 million gallons a day to 15 million gallons per day. 

“It’ll probably push water, definitely farther into West Asheville, possibly even farther into downtown,” Chandler said at the event. “It’ll take a lot of strain off of North Fork, because North Fork’s the workhorse.”

Manheimer noted that the $23 million project is being funded by the Water Resources Capital Improvement Fund, which comes from rate payer fees. 

“We all know that the hurricane confirmed how critical a resilient water system is,” Manheimer said. 

But Chandler also said this project likely won’t be fully operational until about 2032.

“Like everything else with the water system, nothing moves fast,” Chandler said. “So this is going to be a two- to three-year build out.”

Manheimer said Mills River is in the second phase of three total, with the current phase set to wrap up in 2028.

Replacement of a toppled fusegate at North Fork

Helene’s excessive rainfall caused water to overtop North Fork’s auxiliary spillway and topple a fusegate the morning of Sept. 27. Designed as a sort of safety valve to release pressure on the reservoir’s earthen dam, the reservoir’s eight fusegates are designed to tip over at certain water levels. 

Construction work to replace the fusegate will start this fall or in early winter, Chandler said, and will likely cost about $10 million.

Both the city and the state of North Carolina, which regulates North Fork, previously told Asheville Watchdog that the missing fusegate does not pose a significant risk to the dam. 

Finding another potential water source

Manheimer said that the city is “continuing the work of determining the feasibility of building a fourth plant.” The Water Resources Department has applied for an Economic Development Administration grant to help fund site selection.

“The new plant will need to be in the western service area (West Asheville), and will draw water from the French Broad River,” Manheimer said, noting the “very long-term project” will help the city meet rising water demand. “Once a site is selected, planning/design/permitting to operation for a new water treatment plant is generally five to six years.”

Repair of the dams at North Fork and Bee Tree

The dams sustained erosion damage during Helene.

“Due to the technical nature of those repairs and new data that we’ve been gathering since Tropical Storm Helene, that project will begin sometime this fall and again, maybe late winter, depending on things like weather and supply chain and stuff like that,” Chandler said Sept. 3. The cost of the repairs won’t be known until design for the work is complete.

“It is extremely important to note that neither of those dams is in danger of failure. Each has been inspected by engineers of water resources and outside agencies, and have been found capable of protecting our reservoirs and our customers.

Chandler said the damage to the dam at Bee Tree “involves some sloughing of material from the face of the dam due to runoff generated by the heavy rainfall before and during Helene. Also, the spill has some damage from a concrete block that was pushed slightly upward.

Engineers with the city and its contractor, Schabel Engineering, evaluated the North Fork dam. Chandler said it “looks to be in good shape overall, thanks to the auxiliary spillway doing its job.”

Does the city’s plan for resiliency make sense?

John Shaw, a professional engineer who has worked in the water industry for 35 years and previously lived in Asheville for five years, has been critical of Asheville’s water system and its handling of previous water crises. Asked if the city’s current plans make sense for improving resiliency, Shaw said via email, “Yes and no.”

“Giving the city the benefit of the doubt regarding the details of the plans and the limitations of the topography, geography, hydraulics and other resources, they seem to have put together a ‘sketch’ that may (or may not) be adequate,” Shaw said. “If I were reviewing the plan to date, I’d ask the city for the engineering and economic analysis that was performed to eliminate the other options in favor of the one selected. That work is typically referred to as a feasibility study.”

Such a study should be “signed and sealed by a licensed civil engineer and would be submitted to regulatory agencies as the basis for any future request for funding, permitting, etc …,” Shaw added.

Chandler said the city’s plans “were developed internally.”

With the massive undertaking the city has ahead of it, which includes major infrastructure repairs to parks and other city facilities in addition to the water system, Shaw said he’s “hesitant to throw shade on the city.”

But he also said he’s concerned about another potential outage.

“My biggest concern is that the city does not appear to have a contingency plan for another event prior to having all of their ducks in a row,” Shaw said. “That should have been job No. 1. They should be asked to explain in detail how they would react to an event which resulted in similar damage. How are they going to make and convey potable water without those same facilities? If they can’t answer that, then they’ve misstepped.”

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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 is made possible by donations from the community. To show your support for this vital public service go to avlwatchdog.org/support-our-publication/.