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. While customers may not see this pipeline every day, it plays a major role in keeping sewer service reliable across the region. 

What is 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. 

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.

For more information 

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