Crews finish first lining phase to strengthen critical sewer pipe

July 24, 2026

DC Water has completed a major step in the emergency repair of a section of the Potomac Interceptor near Dulles International Airport in Loudoun County, Virginia.

This week, crews finished applying a geopolymer lining inside the pipe. Geopolymer is a strong, cement-like material that creates a protective layer inside the sewer line. This work marks an important milestone in the repair because it helps strengthen the pipe, seal worn areas and protect it from future damage.

The Potomac Interceptor is a large, 54-mile sewer line that carries about 60 million gallons of wastewater each day from parts of Fairfax County, Loudoun County, the Town of Vienna, Herndon, Dulles International Airport and Montgomery County, Maryland to DC Water’s Blue Plains Advanced Wastewater Treatment Plant.

The section near Dulles Airport was identified for emergency repair after DC Water inspected the pipe using advanced tools, including LiDAR, sonar and closed-circuit television cameras. These inspections showed that about 600 feet of 42-inch pipe needed to be reinforced.

Crews are now preparing for the next phase of the repair. That work includes installing cured-in-place pipe, known as CIPP. CIPP hardens inside the existing sewer line and creates another strong layer within the pipe. Crews and contractors are working carefully to complete this phase while limiting impacts to the surrounding area.

By repairing the pipe from the inside, DC Water can strengthen this important sewer line without digging up and replacing the full section from the ground. This approach helps reduce disruption while extending the life of the pipe.

DC Water expects the emergency repair work to be completed by the end of the month. No impacts or interruptions to Dulles International Airport services are expected.