Jacobs helps modernize Virginia’s Alexandria sewer system to improve water quality

(UI) — Jacobs is partnering with AlexRenew, the wastewater treatment authority serving Alexandria and parts of Fairfax County, to help transform the city's sewer infrastructure through the RiverRenew project. The initiative aims to modernize the combined sewer overflow (CSO) system, reducing pollution and improving water quality for local communities.

As the design consultant for RiverRenew, Jacobs is responsible for providing technical leadership and delivering the design for a new, state-of-the-art system that will prevent millions of gallons of sewage from entering the Potomac River, Hunting Creek, and Hooffs Run during heavy rainfall.

The current combined sewer system in Alexandria combines rainwater and sewage in one system. During dry weather, wastewater flows smoothly to AlexRenew’s treatment facility. However, during heavy rain, the system often exceeds capacity, resulting in combined sewer overflows that discharge untreated wastewater into local waterways.

To address these issues, the RiverRenew project involves the construction of a 2-mile-long, 12-foot diameter tunnel, along with two drop shafts, a deep pump station, and other infrastructure upgrades. The project also includes new building facilities at AlexRenew’s site. In March 2024, the project reached a key milestone when a tunnel boring machine, named Hazel, successfully broke through, excavating and constructing the tunnel.

Building major underground infrastructure in one of America’s oldest communities comes with its challenges. Jacobs Project Manager Samer Sadek and other members of the TSJV team spoke with the North American Tunneling Journal about the complexities of the tunnel system’s design and construction. "Every site and location had its unique challenges, so the design and construction process is completely different from one location to the other,” Sadek explains.

The project’s design had to account for diverse geological conditions, including stiff clays and terrace formations. The team is using Jacobs’ Digital OneWater solutions, such as the Replica™ platform for hydraulics and process modeling, and a digital twin to train operators and explore new scenarios.

“The RiverRenew project exemplifies how intricate planning and engineering combine to address the multifaceted challenges of modern water management in one of America’s oldest cities,” Sadek adds. “We’re navigating these complexities and look forward to delivering a sustainable, resilient solution for the community.”

Mark Johnson, Jacobs’ Global Cross Market Director of Tunnel and Ground Engineering, and a local resident, is personally invested in the project. “I understand the importance of CSO tunnel projects like these to local communities and the environment,” Johnson says. “For example, at one of the drop shaft sites on the RiverRenew project, we’ll be covering the shaft and diversion structures with a park that will connect the community to the Potomac River waterfront.”

Before construction, the site was an unused warehouse surrounded by a chain-link fence, with no access to the waterfront. When completed, the area will feature a park where residents can enjoy the riverfront.

The RiverRenew project continues AlexRenew’s commitment to sustainability. The Nutrient Management Facility was the first in Virginia to earn Envision Platinum certification and is one of only 11 facilities in North America with this distinction. The RiverRenew project is on track to achieve both Envision certification and LEED building certification.

Upon completion in 2026, the RiverRenew tunnel system will capture, store, and transport millions of gallons of sewage and stormwater to a treatment plant, where it will be cleaned and safely returned to the Potomac River.

Related News

From Archive

• Most Read
• Most Commented