TRAFFIC ADVISORY: Temporary Lane Closure on I-66 Ramp Start This Week

July 07, 2025
Map of construction area and road closures

Attention drivers. If you use the ramp from Ohio Drive Southwest to I-66, DC Water will be doing construction that requires the temporary closure of one northbound lane beginning as of today, weather permitting. Drivers will still be able to get onto the highway, and the lane will reopen before the evening rush.

The work is scheduled on weekdays during off-peak hours – 9:30 a.m. to 3:30 p.m. – to minimize the disruption during rush hour when traffic volumes are higher. The lane closure is expected to continue for approximately three weeks.

The temporary traffic change supports the Potomac River Tunnel Project, a major infrastructure initiative to improve water quality in the District. DC Water is preparing the site to store materials and equipment for construction of a tunnel system that will capture and redirect overflows of waste and stormwater away from the Potomac River.

When it’s done, this project is expected to reduce these overflows into the Potomac by 93% and transport it to the Blue Plains Advanced Wastewater Treatment Facility. That means cleaner water in the river and a healthier environment for the public and aquatic life.

What to Expect

  • Lane closures during off-peak hours (9:30 AM – 3:30 PM, Monday–Friday)
  • Rock Creek Trail remains open for pedestrians and cyclists
  • Signs and flaggers will help guide you safely through the area
  • Minor delays possible—plan ahead if you can

Near the Lincoln Memorial, DC Water is building an underground facility, as part of the project, that will connect to the existing sewer system and direct overflows into the new tunnel.

Expected to be completed in 2030, the project also ensures compliance with the 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.

Learn more at www.dcwater.com/prt.

Contact Us
Project Email: dcpotomacrivertunnel@dcwater.com
Project Hotline: 202-972-1388
DC Water 24-hour Emergency: 202-612-3400

 

Latest News

Photo of soil removal and excavation

DC Water and its contractor have removed all the soil down to the clay liner between locks 12 and 13, marking 50% completion of the canal clean-up. Soil removal between Locks 13 and 14 was completed earlier this month. Meanwhile, clean-up efforts continue between locks 10 and 12, with sludge removal complete and soil removal now underway.

View of Mary at bottom of shaft inside tunnel shown from above

First turn of cutterhead signals the start of excavation for the Potomac River Tunnel Project

In a defining moment for one of the District’s largest infrastructure investments, DC Water has marked its next major milestone in the Potomac River Tunnel Project. The first tunnel boring machine, Mary, has launched her northbound journey breaking through the soil to signal the start of excavation.

With the first turn of Mary’s drill-like cutterhead underground, the machine pushed forward to begin tunneling, representing the transition from years of planning and preparation to active tunnel construction on the $819 million project.

Photo of the vegetation growing back in the culvert area
  • DC Water has completed soil removal, utilizing excavators and manual digging, to expose the clay lining for the C & O Canal between locks 13 and 14. This is the final step in the clean-up process ...

Upcoming Meeting

Board of Directors Meeting

April 24, 2023

Monday 9:00 AM

Announcement

View of Mary at bottom of shaft inside tunnel shown from above
DC Water Launches Tunnel Boring Machine Mary, Marking Important Step for Potomac River Tunnel Project

First turn of cutterhead signals the start of excavation for the Potomac River Tunnel Project

In a defining moment for one of the District’s largest infrastructure investments, DC Water has marked its next major milestone in the Potomac River Tunnel Project. The first tunnel boring machine, Mary, has launched her northbound journey breaking through the soil to signal the start of excavation.

With the first turn of Mary’s drill-like cutterhead underground, the machine pushed forward to begin tunneling, representing the transition from years of planning and preparation to active tunnel construction on the $819 million project.

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When one of your major sewer lines runs through the Potomac River, a backhoe and trencher won't do. That's why we've got helicopters carrying a 14-ton drill and workers suspended midair over the Potomac.
Upcoming Meeting
Date
April 15, 2026
Wednesday, 9:30 AM

Customer Service Center Announcement

Payment Plan Incentive: provides a credit back of 50% of the last 3 payments made. Eligible participants are residential customers who have had an outstanding balance for 60 days or greater and with an outstanding balance of $500 or more.