Plans to bolster Tysons wastewater system are in the works

Tysons is going to need a bigger sewer system.

With the population expected to continue growing over the next few decades, Fairfax County is starting to prepare now for the anticipated influx of residents — and the additional wastewater they will inevitably produce.

Over the past two years, the county’s Department of Public Works and Environmental Services has been planning upgrades to the sewer pipelines and pump station that serve the Tysons West neighborhood along Route 7 between Westpark Drive and the Dulles Toll Road.

One of several projects in the works to boost northern Fairfax County’s wastewater capacity, the Tysons Wastewater System Enhancements will replace and relocate an existing pump station, while adding more than 7 miles of new sewer pipeline.

“This project will decrease the risk of wastewater overflows and back-ups during periods of high wastewater flows by diverting flow from existing infrastructure,” DPWES said on the project page.

The department will host a virtual public meeting to discuss its proposal at 7 p.m. tomorrow (Tuesday).

@ffxpublicworks will be hosting an informational meeting about the Tysons West Wastewater Conveyance Systems Modifications Project on 𝐓𝐮𝐞𝐬𝐝𝐚𝐲, 𝐌𝐚𝐲 𝟏𝟎 𝐚𝐭 𝟕𝐩𝐦. I invite you to join to learn more about the project and ask questions: https://t.co/LCKgC3yQie pic.twitter.com/qF3HVkLQ9X

— Dalia Palchik (@SupvPalchik) May 4, 2022

According to DPWES spokesperson Sharon North, the Tysons area doesn’t currently have any issues with wastewater overflows or backups, but with the Tysons Comprehensive Plan targeting 100,000 residents by 2050, the current facilities aren’t sufficient to handle that future growth.

DPWES conducted a study that determined wastewater from the northern part of the county should be rerouted to the Noman Cole Pollution Control Plant in Lorton.

To collect and transport the water to that facility, the county will replace its existing pump station — which was built in 1969 and can pump 1 million gallons of water a day — with one that can pump 25 million gallons per day:

The new pump station will be located in the northern part of the Tysons area in a low-lying area in the vicinity of the Spring Hill Metro Station near the existing pump station. The new pump station building will be a state-of the-art facility with energy efficient pumps, odor and noise control, and emergency back-up power. The building will be designed to fit into the community with appropriate architectural treatment.

The project also calls for an approximately 2-mile-long gravity sewer pipe in the Tysons area that will carry water from individual customers to the new pump station. Another 5.5 miles of new pipeline for the force main will bring the water from the pump station to the treatment plant.

The county evaluated eight potential routes for the gravity sewer and 10 possible routes for the force main, citing community and environmental impacts as well as the cost among the criteria considered.

According to a map on the project page, the selected route will transport the wastewater around the Town of Vienna and over to Hunter Mill Road, where it will connect with the existing Accotink sewer line at Route 123.

The overall project carries an estimated cost of $110 million that the county says will be covered by new connection fees, not tax dollars or rate changes.

The design process is expected to take two years, with construction finishing in summer 2026. DPWES says any impacts from construction work will last only a few days in each location along the pipeline.

“Impacted stakeholders will be notified in advance of construction activities. Some of the construction will be performed using trenchless methods to reduce the impact to roads and traffic,” DPWES said. “In addition, stakeholders located near the pump station site will receive information about the pump station facility construction and any potential impacts that may have on them.”