Flowing from the Potomac: Loudoun Water Opens New Pipeline, Treatment Plant

Loudoun Water on Tuesday formally celebrated the opening of Virginia’s most advanced water treatment plant, one designed to keep high quality water flowing through customers’ taps for generations to come.

The $130 million Trap Rock Water Treatment Facility, located along the Dulles Greenway south of Leesburg, draws water from the Potomac River, transports it through a 6-mile underground pipeline and cleans it in the commonwealth’s only two-step ozone treatment system.

The opening coincides with the 60th anniversary of Loudoun Water, which was founded as the Loudoun County Sanitation Authority on May 27, 1959, when the construction of Dulles Airport brought public water and sewer service to the farmland in eastern Loudoun.

Through those decades, most of Loudoun’s water has been supplied by the City of Fairfax, which owned the Beaverdam and Goose Creek reservoirs, and from Fairfax County, which pulled water from the Potomac River.

For the first time, Loudoun Water is tapping the Potomac River on its own to supply part of the 40 million gallons per day needed to serve its 200,000 customers. By 2040, that demand is expected to grow to 90 million gallons per day.

Trap Rock is a project 30 years in the planning to meet those needs. It includes an innovated water banking system that—starting later this year—will convert former quarries to storage reservoirs. The first will hold 1 billion gallons for emergency use; ultimately 20 billion gallons will be stored in quarries now mined by Luck Stone north of the treatment plant.

The water banking quarry concept is credited to Loudoun Water engineer Tim Coughlin, now retired. It wasn’t entirely dismissed as harebrained when he first proposed it in 1988, but it was an idea years ahead of its time. Then, there was little development west of Country Side and Rt. 28 was still a two-lane road, although dirt was moving to build Ashburn Farm and Ashburn Village as the county’s next growth wave ramped up.

At that time, Goose Creek was the only water source, clearly not large enough to keep up with demand. Coughlin broached an idea with then General Manager Ken Shelton.

“I said, ‘Ken, the Potomac River has plenty of water most of the time, but as a water company it has to be all the time,’” Coughlin recalled Tuesday. “So all it is, is a question of storage. We can’t build reservoirs anymore, forget that. You’re not going to get that permitting wise. We said all we need is a big holding ground. I said, ‘we’ve got those quarries there.’ And he said, ‘Tim, great idea, we’ve got a lot going on, but keep thinking about it.’”

During those early discussions, Luck Stone representatives thought the concept was a bit off-the-wall, but ultimately the third-generation, family-owned company became enthusiastic and supportive partners, Coughlin said.

The new plant and extensive storage system were designed with an eye toward preparing for Loudoun’s growth, as well as addressing anticipated impacts of climate change, and two extreme weather conditions were fundamental in formulating the project and pushing it forward.

Dale Hammes, who recently retired as Loudoun Water’s general manager after 40 years of service, said proof of the storage potential of Luck Stone’s diabase quarries was provided by Mother Nature. When Hurricane Agnes hit in 1972, Luck Stone’s northmost quarry filled with water. It stayed that way for years, until the company pumped it out to resume mining operations there. That was a solid demonstration of excellent holding capacity of the quarry’s tight rock walls, he said.

Although the water authority had purchased land for the Potomac River intake in 1991, Coughlin said the project largely remained in a holding pattern until another severe weather event in 1999. That’s when the Beaverdam Reservoir virtually dried up during a prolonged drought. While Loudoun was able to safely provide the needed water supply through a contract with Fairfax Water, efforts to provide a more stable source in the wake of the county’s continued rapid development moved into higher gear. A decade later—with extensive talks with Luck Stone and a prolonged negotiation to secure a permit to draw water from the Potomac, the first granted by Virginia’s Department of Environmental Quality—the plans for the new system were given the go-head.

“Today’s ceremony is a reminder of Loudoun Water’s mission, which is to sustainably manage our water resources and the advocacy of health, environment and quality of life,” Loudoun Water General Manager Carla Burleson said.

Loudoun Water Chairman Shaun Kelley said the project’s focus on protecting the environment was the key to winning approval.

“The system will allow Loudoun Water to withdraw water from the Potomac when the river is flowing sufficiently and, alternatively, use stored water during droughts or other water emergencies,” Kelley said. “This approach offers flexibility and climate resiliency, while protecting the Potomac River and its ecosystem.”



2 thoughts on “Flowing from the Potomac: Loudoun Water Opens New Pipeline, Treatment Plant

  • 2019-05-22 at 9:04 am

    I am curious if this will help with the quality of the water?? Or just a better supply of the crappy water the town already offers?

  • 2019-05-22 at 2:34 pm

    Tim Coughlin deserves a medal. This is a genius plan, long in the making.

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