Scott’s Run Nature Preserve to close for emergency wastewater pipe cleaning

(Updated at 3:30 p.m. on 3/29/2024) Clogged-up pipes will force Scott’s Run Nature Preserve to close for more than a month, starting later this week.

Contractors will begin work on the “emergency project” to clear and repair wastewater pipes in the McLean park this Thursday (March 28), the Fairfax County Department of Public Works and Environmental Services recently announced.

The 385-acre park at 7400 Georgetown Pike will be closed throughout the project’s first phase, which is expected to take about six weeks and will remove an estimated 80 tons of sediment from the pipes, according to DPWES.

Also known as siphons, the pipes carry wastewater from McLean across the Potomac River and into Maryland, connecting to a DC Water interceptor through Carderock National Park.

“During a recent inspection two of the three pipes at the wastewater siphon were found to be non-operational,” DPWES said in a news release. “An emergency repair is necessary, as there is no reasonable bypass alternative if the last pipe fails, which would mean millions of gallons of sewage per day going into the Potomac.”

According to the project page, the park needs to close during the project so construction crews and equipment can access the trails without creating conflicts for visitors or pushing pedestrians off-trail, which would damage the natural environment.

Work will take place Monday through Saturday from 7 a.m. to 7 p.m., depending on the weather. The closure will apply to all trails and the east and west parking lots.

In addition to removing sediment, which will be transported out of Scott’s Run daily by truck, the project will involve replacing valves and cleaning the siphon barrels. The siphon barrel cleaning will be done in Carderock National Park.

A second phase of work focused on maintenance repairs is expected later, requiring another park closure, but the exact timing will be determined after “additional investigations are made during the cleaning process,” DPWES said.

In total, the work at Scott’s Run is expected to take three months, though the overall project has an anticipated timeline of six to nine months.

DPWES says no other properties should be affected by the project, and traffic into and out of the Scott’s Run parking lot will be “limited” after the contractors arrive Thursday morning.

“Materials and construction equipment for the project will be safely stored onsite,” the project page says. “Additionally, Fairfax County McLean District Police have been notified of the project and will be monitoring traffic patterns in the area to ensure safety of residents and commuters.”

The county says it’s identifying “methods to optimize and enhance its inspection and cleaning procedures to reduce the likelihood” that an emergency response of this level will be needed in the future.

Correction: DPWES says 80 tons of sediment are being removed from the Scott’s Run pipes, not 80,000 tons as first reported.