Following a nearly year-long construction effort, DC Water has completed repairs on a nine foot diameter, 140-year old sewer tunnel on 22^nd Street Northwest. Construction was done in two phases, with the second phase completed one month ahead of schedule and under budget.

The work zone in the area of 22^nd and Q streets is being demobilized. All northbound lanes are now open, and southbound lanes will be reopened later today prior to the evening rush hour. 

The tunnel section is part of the Northwest Boundary Trunk Sewer, built in the 1800’s. Last year, an inspection revealed a large void in the soil above measuring 13 feet long and 10 feet wide and the tunnel in danger of collapse, necessitating the long-term closure of a section of 22^nd Street. 

Significant structural issues were also identified, as well as upstream and downstream from the emergency repair. These included longitudinal cracks, missing cobblestones and bricks, and root penetration prompting emergency repairs.

Construction, sometimes 24 hours a day, seven days a week, posed challenges with crews working two stories below ground in difficult conditions. At the same time the sewer pipe remained active with combined stormwater and sewer debris flowing through and prompting work stoppages when heavy rain inundated the system. 

The work involved reinforcing the sewer tunnel and stabilizing the soil around the initial void. This required injecting grout into the soil, framing the walls with rebar, and using high-pressure spray-applied shotcrete and geopolymer, four inches to as much as nine inches thick. This included: 

• 139,000 linear feet of rebar
• 25,450 rebar anchors
• 28 tons of shotcrete
• 459 tons of geopolymer

Emergency repairs began in July 2024 as part of the first phase of the project which involved stabilizing the soil and reinforcing the tunnel around the initial void. Additional inspections identified more structural deficiencies requiring a second phase to repair more than 1200 linear feet further upstream and downstream.

DC Water worked closely with the District Department of Transportation to minimize the disruption to traffic in the area and appreciates residents and commuters for their patience while repairs were made for the safety of the community. To help relieve the impact of the road closure, one northbound lane of 22^nd Street earlier this year while construction continued.

DC Water operates approximately 2,000 miles of combined, separate, and stormwater sewers. Addressing aging water and sewer infrastructure throughout the District is a critical part of the 10-year, $9.6 billion Capital Improvement Program. This includes replacing or rehabilitating similar large diameter sewer lines that have reached the end of their useful life.

For more information about DC Water’s investment in infrastructure improvements view our Capital Improvement Program.