Spurred primarily by projections for a significant population increase in the coming decades in greater Charlotte and surrounding Mecklenburg County, Charlotte Water has begun construction of a more than $380 million wastewater treatment facility.

With an expected completion date in 2026, the Stowe Regional Water Resource Recovery Facility will expand the water and wastewater utility’s service footprint westward, across the Catawba River, to two neighboring communities: Mount Holly and Belmont, located in eastern Gaston County, says Nicole Bartlett, a division manager within the utility’ engineering department.

Named after the late Joseph C. Stowe Jr., a former director of Charlotte Water, the new facility is notable because it’s the biggest and most expensive project the utility has ever tackled. In addition, it will require drilling six bores that will hold 26- to 42-inch-diameter force mains made from high-density polyethylene pipe.

At least four of the bores will be drilled by Michels Corp., a global energy and infrastructure construction contractor based in Wisconsin, using horizontal directional drilling.

“A preliminary engineering study showed this was the best option to get from Point A to Point B, as well as the safest and least impactful method in terms of its effect on wildlife and recreational use of the river,” Bartlett says.

“This big of an HDD project is a pretty big deal for us. On a scale of one to 10, it’s pretty high up there. It’s also a massive project, with lots of moving pieces and many stakeholders and multiple general contractors.”

A boring situation

HDD begins by boring a pilot hole that’s smaller than the final bore, followed by more bores (a process called reaming) with increasingly larger-diameter drill bits. The final bore is about 12 inches in diameter larger than the pipe it will house — about 36 inches for this project.

After that, sections of HDPE pipe are fused together, pressure tested for leaks and then pulled through the bore.

Two of the bores are 3,100 feet long and travel through bedrock 65 to 76 feet below the Catawba River and nearby Long Creek, connecting a new pump station in Mount Holly to Charlotte Water’s existing Long Creek Pump Station.

The second set of bores will be around 1,142 feet long and about 70 feet deep. They’ll travel under Long Creek to connect the Long Creek Pump Station to the Stowe facility, which will be located on a 79-acre parcel on a peninsula bordered by the river and Long Creek, right across the river from Mount Holly.

The third set of force mains will be installed roughly 50 or more feet deep under the river and will connect a new pump station in Belmont to the utility’s existing Paw Creek Pump Station. The distance of those bores has yet to be determined.

The two Mount Holly bores are already complete. The remaining bores are expected to be finished in 2023 for Long Creek and 2025 for the Belmont portion of the project.

Boring two force mains for each of the three legs of the project provides redundancy that allows for continuous service without disruption in case one main must be taken offline for maintenance or repairs, Bartlett says.

More efficient treatment

The project — funded by bonds that will be paid back via user fees, with no rate increase for Charlotte Water customers — made sense for several reasons. The first is an expected 50% population growth in the Charlotte metro area by 2050, to 4.5 million people from 3 million, according to a study performed in 2021 by the Charlotte Regional Business Alliance.

Without the Stowe facility, the utility would have to upgrade an extensive portion of its wastewater collections system, including replacing more than 20 miles of underground wastewater sewer lines at considerable cost and disruption to the community.

“This is a far better solution for our environment and for our ratepayers,” Bartlett notes.

The Stowe facility will initially process and treat 15 million gallons per day and will eventually expand to handle up to 25 mgd, which is enough to accommodate regional growth far into the future, Bartlett notes.

The new facility also will improve operating efficiency and environmental sustainability. Waste currently generated in northern Mecklenburg County must travel more than 20 miles — aided by the Long Creek and Paw Creek pump stations — to get treated at the utility’s McAlpine Creek Wastewater Management Facility, the largest of the utility’s five existing treatment plants.

“It’s more energy efficient to treat wastewater closer to where it’s generated,” Bartlett says. “It’ll reduce our carbon footprint because the utility will use less electricity to operate the pump stations.”

Reducing the distance wastewater travels also decreases the chances of wastewater spills, she adds.

Cost-effective approach

Another compelling reason to go ahead with the project was the high cost of replacing aging wastewater treatment infrastructure in Mount Holly and Belmont. Studies performed during the planning stage of the project showed that it would be more cost-effective, efficient and environmentally friendly to build the Stowe facility and retire two treatment plans, one in Belmont and the other in Mount Holly.

“The new facility also supports Charlotte Water’s philosophy of consolidating existing plants — taking a regional approach to wastewater management,” Bartlett says. “This also will improve the water quality in the Catawba River and minimize wetland impacts from treated water discharges into the river.”

Furthermore, the state-of-the-art Stowe facility will use a process called densification — essentially an enhanced settling process — which will more effectively process and purify wastewater to meet heightened state and federal water quality standards.

“Stowe will be the first greenfield wastewater treatment plant in the country to use densification,” she says.

Essential partnerships

Mount Holly and Belmont secured Clean Water State Revolving Fund loans to pay for their portions of the project. Each community will pay for a new pump station and Mount Holly is paying for its force mains.

“Residents in those communities won’t get a bill from Charlotte Water,” Bartlett explains. “Each city will become a single customer known as a significant industrial user (SIU).

“We will send a single monthly bill for wastewater treatment services to each municipality and after that, it will be up to each one to figure out how much to charge their customers and set user rates as they see fit.”

Partnering with the two communities was instrumental to the project moving ahead because their state discharge allocations will eventually be transferred to the discharge permit for the Stowe facility.

“Stowe couldn’t exist unless we partnered up because without their permits, there wouldn’t be any allocations left for the Stowe facility to discharge treated water,” she says.

Members of city councils in both Mount Holly and Belmont formally approved interlocal agreements that formalized the partnerships in 2018 and 2019, respectively.

Staggered implementation

Mount Holly and Belmont will be phased into the Charlotte Water collections system. Mount Holly is expected to start sending its wastewater to the Long Creek Pump Station by the end of 2024. But for the first two years, it will be treated either at the McAlpine treatment facility or the utility’s Irwin Creek Wastewater Treatment Plant.

“That’s because the Mount Holly wastewater treatment facility is in worse condition than Belmont’s, so the city wanted to be taken offline earlier, before the Stowe facility is complete,” Bartlett explains. “We made the Mount Holly hookup a priority so they could send waste to Charlotte Water as soon as possible.”

Belmont’s wastewater will initially get pumped to the Paw Creek Pump Station and then to the McAlpine facility, starting in 2006. In five to 10 years, when the Stowe facility expands enough to handle up to 25 mgd, Belmont’s waste will then flow north from the Paw Creek facility to the Stowe facility.

“In the end, Stowe will end up serving all of western Mecklenburg County and eastern Gaston County,” Bartlett says.

However, the Long Creek station still will be able to send wastewater to the Irwin or McAlpine treatment facilities and the Paw Creek station still will be able to send wastewater to McAlpine if needed, she points out.

“We’re going to keep those connections functional, just in case a ton of flow would unexpectedly come down the line or if we have to do maintenance work (upstream). When the Stowe facility goes online, we’ll be well-positioned to handle future growth and also will have greater flexibility with how wastewater flow is managed in our collections system.”