DC CLEAN RIVERS - POTOMAC RIVER TUNNEL PROJECT

DC Water is mobilized and ready to begin major construction for the Potomac River Tunnel Project at the Rock Creek Trail site west of the Watergate Complex. This marks the beginning of crucial work that will include utility connections, the opening of a new section of the Rock Creek Trail, and deep excavation to support the tunnel system. The first visible activity begins on our about July 23, 2025, with temporary lane and sidewalk closures to install essential water and sewer connections.

The Potomac River Tunnel Project is designed to reduce the overflow of sewage and stormwater into the river during heavy rainfall, by capturing and holding the overflow until it can be treated at the Blue Plains Advanced Wastewater Treatment Plant.

Here’s what to expect in the coming months:

Starting on or about July 23, 2025: Utility Connections

What’s Happening

Crews will install water and sewer connections to support the tunnel construction site.

Impacts

• When: Weekdays, July 23–August 5, from 9:30 a.m. to 3:30 p.m.
• Where: Rock Creek and Potomac Parkway NW (between Virginia Avenue NW and F Street NW)
• Traffic Changes:
  
  • One lane closed in each direction during non-peak hours
  • Rock Creek Trail will remain open

Late Summer 2025 - New Rock Creek Trail Opens

What’s Happening

A new, permanent section of the Rock Creek Trail will open to safely reroute pedestrians and cyclists around the construction zone.

What to Expect:

• The new trail will remain open throughout construction
• The current trail next to the Parkway will close and become part of the work zone
• Once the project is complete, the original trail will be restored

Starting August 2025: Ground Stabilization for Tunnel Work

What’s Happening

Crews will begin drilling deep into the ground to provide structural support during excavation. This includes building underground walls using large concrete columns to support the soil and control groundwater during excavation. The drop shaft will go down almost 110 feet with a diameter of 45 feet – enough to fit 72 shipping containers.

What to Expect

• Work will stay within the construction site — no traffic impacts
• Large drill rigs will install steel-encased concrete columns (called secant piles)
• Some noise during drilling and soil removal
• This phase will last about 9 months

 Noise may be noticeable during drilling operations. Construction noise is monitored to ensure it does not exceed the District's standard limits. Every effort will be made to minimize noise and maintain safe access to the trail and surrounding areas.

We appreciate your patience and cooperation as we work to improve water quality in the District.

At the construction site along the Rock Creek Trail, DC Water is constructing a diversion facility to connect the sewer outfall to the Potomac River Tunnel. The facility includes a diversion chamber, approach channel, drop shaft, and ventilation components.

Project Details

The Potomac River Tunnel is a big step forward in DC Water’s efforts to keep our rivers cleaner. The 5.5-mile tunnel will catch excess stormwater and sewage during heavy storms—something that would normally overflow into the Potomac River. Instead, the excess will be diverted to Blue Plains for treatment. Right now, about 650 million gallons of that polluted water ends up in the river every year. This tunnel will cut that by 93% and instead of overflowing 74 times in a typical year, it will only happen four times.

The tunnel also complies 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.

For More Information:

Project Email: dcpotomacrivertunnel@dcwater.com

Project Website: www.dcwater.com/prt

Project Hotline: 202-972-1388

DC Water 24-hour Emergency Command Center: 202-612-3400