DC Water is rehabilitating a section of the Potomac Interceptor near Dulles International Airport in Loudoun County, Virginia. This project will strengthen an important sewer pipeline that helps carry wastewater from parts of Virginia and Maryland to the District and DC Water’s Blue Plains Advanced Wastewater Treatment Facility. 

The work is part of DC Water’s ongoing effort to keep critical infrastructure in good condition, reduce the risk of future repairs, and protect public health and the environment. This section of pipe was prioritized for emergency repairs, after advanced inspections of the full 54-mile sewer line found corrosion and exposed steel reinforcing bars. While customers may not see this pipeline every day, it plays a major role in keeping sewer service reliable across the region. 

Project Updates

Critical Pipe Repairs Complete, Work to Install New Manhole and Restoration Underway
July 30, 2026

DC Water and it's contractor have finished the pipe repairs on a section of the Potomac Interceptor at Dulles International Airport. This marks the first of four emergency repair projects to be completed on the 54-mile sanitary sewer line. 

Work began in June after new inspections found serious damage inside the 54-mile sewer line. The damage included corrosion, worn concrete, and exposed steel supports. Crews repaired a 175-foot section of the 42-inch pipe with a strong, concrete-like lining. The final step in repairs used a cured in place liner It’s a flexible liner inserted into the pipe and hardened in place to form a new pipe within the existing one. Together, these repairs restored the pipe to like-new condition.

The Dulles site is one of four Potomac Interceptor locations DC Water identified for emergency repair. With pipe repairs done, DC Water will install a new manhole at the site and begin the cleanup and restoration. That work should finish by early September.

Learn more here: Critical Pipe Repairs Complete On Potomac Interceptor Sewer Line at Dulles

Major Step Complete in Emergency Repair, Next Phase to Strengthen Pipe Set to Begin
July 24, 2026 

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

Crews expect to begin the next phase of the repair Tuesday, July 28. 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.

DC Water expects the emergency repair work to be completed by the end of the month. Learn more here:  DC Water Completes Major Step in Potomac Interceptor Repair Near Dulles Airport

July 30, 2026 News Release
Critical Pipe Repairs Complete On Potomac Interceptor Sewer Line at Dulles
First of four emergency repairs on Potomac Interceptor finished

July 27, 2026 News Release
DC Water Completes First Major Step in Potomac Interceptor Sewer Line Repairs at Pennyfield Lock
Crews also reach a major milestone near Dulles International Airport as the next phase of repairs begins this week

July 2, 2026 News Release
DC Water to Continue Daily Potomac River Testing Through July 31 as Potomac Interceptor Repairs Continue

Why this work matters 

Like roads, bridges, and water mains, sewer pipes need maintenance as they age. This project will reinforce a section of the Potomac Interceptor so it can continue to safely move wastewater for years to come. Investing in this work now helps prevent larger problems later and supports reliable sewer service for customers and communities. 

Project Details 

🛠️ Work: Rehabilitation of a major sewer pipeline to strengthen the existing pipe and extend its useful life 

📍 Location: Near Dulles International Airport in Loudoun County, Virginia 

📅 Timeline: June 2026 through September 2026 

📏 Project length: Approximately 600 linear feet of pipe will be rehabilitated 

⭕ Pipe size: 42 inches in diameter 

⏰ Typical work hours: 7 a.m. to 5 p.m. 

🚧 Traffic and service impacts: No impacts or interruptions to Dulles International Airport services are expected 

What customers and stakeholders can expect 

Early construction activities include building access roads and setting up a temporary pumping system and pipeline to bypass the section being repaired. The temporary system allows wastewater to keep moving safely while crews repair the pipe. This helps DC Water complete the work without interrupting sewer service. 

Crews will use methods that allow much of the work to happen inside the existing pipe. This reduces the need for large open trenches and helps limit impacts to the surrounding area. 

How the pipe will be repaired 

DC Water will repair the pipe using two methods. Crews will apply geopolymer, a strong cement-like material that forms a protective lining inside the pipe. Crews will also use cured-in-place pipe, or CIPP, which hardens in place to create a new pipe layer inside the existing sewer line. 

Once these materials harden, they help seal worn areas, strengthen the pipe, and protect it from future damage. These repair methods allow DC Water to improve the pipeline without replacing the full section from the ground up.

About the Potomac Interceptor 

The Potomac Interceptor is a large sewer pipe that carries about 60 million gallons of wastewater each day. It collects wastewater from parts of Fairfax County, Loudoun County, the Town of Vienna, Herndon, Dulles International Airport, and Montgomery County, Maryland and carries it to Blue Plains, where it is treated and the water is returned safely to the environment. 

For more information 

Project email: potomac.interceptor@dcwater.com
Project website: dcwater.com/potomacinterceptor 
DC Water 24-hour Emergency: 202-612-3400