RiverRenew Tunnel System Project

The RiverRenew Tunnel System Project was legally mandated by a Virginia state law passed in 2017. It involves the design and construction of a storage and conveyance tunnel system and a tunnel dewatering and wet weather pumping station in Old Town Alexandria, VA.

The project involves constructing an 11,500-foot-long, 12-foot-inner diameter storage and conveyance tunnel about 100 to 140 feet deep, along with several key structures including multiple drop shafts, an interceptor sewer, a dewatering and wet weather pumping station, and a screening shaft. A custom-built, 380-ton EPB TBM named “Hazel,” after environmental justice pioneer Hazel Johnson, was unveiled in July 2022 to excavate the tunnel. The TBM traveled under and along the Potomac River for two miles and holed through in March 2024.

Diversion facilities will redirect stormwater and wastewater from the city’s sewer system into the tunnel, while a six-foot diameter, 2,500-foot-long interceptor sewer line constructed by micro tunneling and open cut will collect and transport sewage to the tunnel system. A key component of the project is the construction of a tunnel dewatering and a wet-weather pumping station, which will remove and transport captured storm- and wastewater to treatment facilities, even during heavy rainfalls. Environmental protection measures, such as water treatment systems with real-time monitoring, ensure minimal risks and environmental impact during construction.

Upon completion, the project is expected to reduce the average annual volume of overflows from 140 million gallons to less than 16 million gallons, and the frequency of overflows from around 70 events per year to fewer than four. The tunnel system will integrate seamlessly with Alexandria Renew Enterprises’ existing treatment plant, enabling captured sewage to be processed safely and discharged in compliance with environmental standards. This ambitious project not only addresses critical infrastructure needs but also provides a long-term solution to protect Alexandria’s waterways for future generations.