DC Water is beginning critical ground stabilization work this week for the Potomac River Tunnel Project. The work will support the construction of a new underground diversion facility near the Capital Crescent Trail and is part of a larger effort to reduce sewer overflows into the Potomac River. The construction will connect the existing sewer line where it overflows into the Potomac with the new tunnel system.

Once the ground is stabilized, crews will begin digging for key parts of the facility, including a ventilation vault, a drop shaft, and diversion chamber. These structures will help reduce the amount of sewer and stormwater that goes into the River, improve water quality, and protect the environment by capturing the overflow inside the tunnel until it can be treated.

📣 What to Expect:

To stabilize the ground before excavation, crews will install secant piles—deep concrete columns that form a retaining wall to prevent soil collapse and groundwater intrusion.

During this time, you may notice increased noise from drilling and muck removal, as well as more service vehicles in the area. DC Water is committed to minimizing disruption and will monitor noise levels to ensure they remain within District regulations.

🔧 Key Construction Activity: Secant Pile Installation

• Increased noise during drilling (within legal limits)
• More service vehicles in the area
• Safe access to the trail will be maintained
• Noise monitoring will be ongoing to minimize disruption

📅 Construction Schedule:

• Ventilation Vault
  • Date: Starting on or about July 16, 2025, to August 8, 2025 (weather permitting)
  • Time: Monday–Friday,7:00 a.m. to 7:00 p.m.
• Drop Shaft
  • Scheduled: September 2025
• Diversion Chamber
  • Scheduled: October 2025

📍 Location:

Construction is taking place west of the Alexandria Aqueduct Ruins along the Capital Crescent Trail where an underground diversion facility is being built.

All work will take place within the designated construction site. Safe access to the trail and surrounding areas will be maintained throughout the project.

Project Details

The Potomac River Tunnel is a major part of DC Water’s Clean Rivers Project. This 5.5-mile tunnel will collect a mix of sewage and stormwater and send it to the Blue Plains Advanced Wastewater Treatment Plant instead of letting it overflow into the Potomac River, and ultimately, Chesapeake Bay. Right now, about 650 million gallons of untreated overflow enter the river each year, carrying trash and bacteria that harm the environment and aquatic life.

Once complete, the tunnel will reduce these overflows by 93% and cut the number of overflow events from 74 to just four in a typical year, ensuring compliance with a 2005 Federal Consent Decree entered by DC Water, the District of Columbia, the US Environmental Protection Agency, and the US Department of Justice, as amended in January 2016.

We appreciate your patience. You can sign up for construction activity notices sent via email by contacting dcpotomacrivertunnel@dcwater.com.

ℹ️ Project Information

• Email: dcpotomacrivertunnel@dcwater.com
• Website: www.dcwater.com/prt
• Hotline: 202-972-1388
• 24-Hour Emergency: 202-612-3400