How do you build a massive water pumping station on the shore of a recreational lake with high-end homes? Make it look like part of the neighborhood.
Five years ago, Garney Construction bid on an unusual water supply project—building a source-totreatment water system that included a large intake pipe and a pump station on a lot in the middle of an upscale, lakefront neighborhood.

Today, that project in a Charlotte, N.C. suburb is nearing completion, thanks to a lot of engineering ingenuity and not a little bit of architectural flair.
“It’s a design-build project,” explains Jeff Seal, director of Garney Construction. “The Raw Water Infrastructure Project is part of Union County’s Yadkin Regional Water Supply Project. The county put out a request-for-proposal that included the intake, pump station and approximately 30 miles of pipeline. It’s one giant project.”
Garney Construction, an employee-owned company founded in Kansas City, Mo. in 1961 that now has offices across the U.S., specializes in water projects—water supply, water transmission lines, water treatment and desalinization plants. They were awarded the contract for the entire raw water system, from intake at Lake Tillery to the treatment plant.
“We were uniquely qualified for the project due to our experience,” Seal says. “Nearly all of our work is within the water or wastewater industry. And we perform the marine work, with our own divers, which is unique for water/wastewater contractors.”
The contract was awarded on best value, not solely on cost, Seal says.

“The county said, ‘we need this much water, here’s where you need to get it from, and here’s where it needs to go. You guys figure it out.’ We brought in a design partner, Hazen, to work from the client’s concept. We had very limited information to get started with.”
The most visible part of the project is the pump station disguised as a high-end, lakefront home.
“The water authority bought a lot for the intake that’s surrounded by houses,” Seal says. “As you can imagine, the neighbors weren’t too excited about having a massive pump station as their new neighbor on a recreational lake. All of our access comes through a tight area. But when it’s all done, it’s going to look like a house, not a pump station.”
****
Construction of the system began with drilling secant piles to provide structural support for the 45-foot-deep by 45-feet-diameter shaft for the pump station, from which the micro-tunneling for the intake pipes was launched.
“The way we do this is the shaft for shaft serves as the launching point micro-tunnel machine,” Seal explains. “The micro-tunnel extended about 300 feet through the bottom of the lake; it was about 40 feet deep where the micro-tunnel machine daylighted. It’s a closed-face, pressure-balanced machine. Once it daylights through the lake bottom, we seal off the casing pipe from the shaft. Then we flood the intake pipe so you don’t have a pressure differential. Before we disconnect the micro-tunnel machine, we flood the inside of the micro-tunnel and add a little positive pressure so that it comes off easy, then disconnect it and float it to the surface to be lifted onto the barge.
“When the micro-tunneling operation is complete, the shaft becomes the wet well of the pump station and the water level in the wet well stays at the same elevation as the lake. Pumps sit above the wet well with suction shafts that go to the bottom of the wet well.
“The pump station houses two vertical turbine pumps, with space for an additional three pumps, which pump 6,000gpm each for Union County,” Seal continues. “Water will go through 25 miles of 42-inch steel pipe to a hydraulic control stationwhch serves as an air gap in the system. Raw water flows from the HCS through a 54-inch pipeline to the water treatment plant.

“The only part of the intake system that’s visible on the lake are two pipe-support towers built on eight piles. The tops of the towers sit just above the surface of the lake. The valves that control lake water going into the wet well are electrically operated and have a manual stand that comes up to the platform on the lake. If something were to go wrong, the county could manually operate the valves.”
Placing the towers was a challenge.
“We built the towers above water and set them in place.” Seal says. “The drilled piles are 30-inch diameter which received a rebar cage and tremiefilled with concrete. The legs of the towers were fabricated from 12-inch H pile. We had only a three-inch variance to have the feet fit into the piles in the rebar cages, so we had to be very precise when we drilled the casings. In order to get this tight tolerance, we fabricated templates and drilled through the templates. When we went to set the towers, everything fit.”
But the larger challenge was getting material and equipment to the construction site. The entrance to the lot is small and the lot itself has virtually no room for on-site storage.
“It’s also a land-locked lake,” Seal says. “We used Flexi-float and Poseidon barges. There wasn’t navigable waterway access to the project, but we were able to use a nearby access point to put in all of our barges and equipment, which was trucked to the access point.”

The principle of minimizing the impact of everything connected to the project’s construction had multiple benefits—among them, relations with the neighbors who lived closest to the site.
“They’ve been good to work with,” Seal says.
“We’ve been as sensitive to their needs as possible. We’ve had a massive crane and barge set up in their back yard. If you live on a lake, you don’t expect to see a 50-foot by 80-foot barge with 100- ton crane on it. It’s pretty big stuff. But it’s worked out nicely.”

PROJECT OVERVIEW
The Raw Water Infrastructure Project is part of Union County’s Yadkin Regional Water Supply Project which has been developed to ensure a long-term, sustainable water supply to its current, and projected future customers in the Yadkin River Basin Service Area.
In May 2013, the county and the Town of Norwood completed an Interlocal Intake and Transmission Agreement that provided the framework for bringing raw water supply from Lake Tillery to the County’s Yadkin River Basin Service Area. This service area lies primarily within the Rocky River Interbasin Transfer (IBT), which is part of the greater Yadkin River Basin.
In May of 2017, after extensive stakeholder engagement, river basin modeling, and completion of an Environmental Impact Statement (EIS), the North Carolina Environmental Management Commission (NC-EMC) granted Union County an IBT Certificate for 23.3 MGD. The IBT certificate allows Union County to transfer up to 23.3 MGD from Lake Tillery to Union County’s Rocky River IBT Basin every month.
The construction phase includes a new single raw water intake into Lake Tillery with two intake screens located at different lake depths, as well as a common wet well to supply raw water pumps for both the Town of Norwood and Union County. Pumping equipment includes two 1,250 hp vertical turbine pumps rated at 6,000 gpm each and three 30 hp vertical turbine pumps rated at 1,600 gpm each for Union County and the Town of Norwood, respectively. The intake piping and wet well have a capacity of 45 mgd [million gallons per day].
The wet well and pump station building all stand on 54 permanent secant piles for structural support. The intake pipeline is 54-inch diameter steel piping and is approximately 480 feet in length. The scope also includes emergency/standby power facilities and the demolition of existing structures on the Town of Norwood property. The raw water intake construction requires the continuous operation of the Town of Norwood’s existing intake infrastructure and water treatment plant, so once the new structure is in service, the existing intake will be removed from the site.
The marine section includes the mobilization of crews to the lake for the wet recovery of the 54- inch microtunnel boring machine from the bottom of the lake at the completion of the 300-foot tunnel.
The next steps included construction of the piping support foundations approximately 40 feet below the lake surface. the foundations consist of 30-inch cased piles 80 feet deep, followed by the installation of rebar cages and placement of concrete within the casings by the tremie method. With the foundational support piles completed, crews assembled on land and then placed 180 feet of 54-inch coated steel raw water intake header pipe equipped with two 72-inch diameter cylindrical intake screens supported on steel structure towers.
The intake screens are installed on two different levels and are equipped with motor operators designed to rotate against a fixed brush to clean off lake debris. The header also includes 42-inch screen isolation butterfly valves.
During the proposal phase, Garney recommended using secant piles for the pump station walls. This served not only as the excavation support system, but also the permanent walls of the wet well. This saved on construction costs, and also allowed the owner to purchase less land and mitigated impacts to the surrounding neighbors.
This progressive design-build project began with a pre-construction phase that includes overall project scoping, design workshops, development of an initial opinion of cost, design services through 30 percent, and design completion to 60 percent including a GMP and schedule for the construction phase.
Yadkin Regional Water Supply Project— Raw Water Infrastructure
(Progressive Design-Build)
Norwood, North Carolina
DELIVERY METHOD: progressive design-build
ENGINEER: Hazen and Sawyer
START DATE: September 2018
COMPLETION DATE: November 2023
ORIGINAL CONTRACT: $156,155,804
FINAL CONTRACT: $156,155,804
Warren Miller is the editor of Marine Construction Magazine. Jeff Seal is the Nashville-based director of Garney Construction
Reprinted from Marine Construction Magazine Issue II, 2024
