Potomac Interceptor Project
What is the Potomac Interceptor?
The Potomac Interceptor (PI) sanitary sewer system carries about 60 million gallons of wastewater daily from areas near Dulles Airport to the Potomac Pumping Station in Washington, DC. Flows from the pump station are then sent to the Blue Plains Advanced Wastewater Treatment Plant for treatment before discharge into the Potomac River.
The PI was built as a result of the enactment of Public Law 86-515 (the Act), by the 86th Congress, on June 12, 1960. The Act authorized the District of Columbia to plan, construct, operate, and maintain a sanitary sewer to connect Dulles to the Washington, DC sewer system.
The PI serves Fairfax, Loudon County, Town of Vienna, Herndon, Dulles Airport and Montgomery County, MD. DC Water is performing replacement and rehabilitation of the PI.
Potomac Interceptor Projects
Potomac River Crossing- Click here for Project Factsheet.
PI02- Project Webpage Coming Soon!
Helicopters at Great Falls?
From January 27 to February 2, 2025, DC Water conducted geological investigations in the Potomac River to determine the most effective strategy and design alternatives for the replacement and rehabilitation of the Potomac Interceptor.
Rock core samples were taken just below the Washington Aqueduct dam in Great Falls. This investigation will provide DC Water’s engineers a better understanding of the geology in the area. The investigation required the transport of both workers and a drilling rig by helicopter that drilled up to 50 feet in depth at five locations within the Potomac River.
More information on rock cores and what occurred during the week long investigation can be found here. Find the latest news and photos here.
Did You Know?
Buildings in Disguise- There are multiple buildings serving as odor control facilities. These facilities draw odorous air from the Potomac Interceptor, pass the air through a media-filled vessel to remove the majority of odors, and discharge the treated air to the atmosphere. The facilities are part of the Potomac Interceptor's Odor Control Abatement Program.
Just Facts
Over 54 Miles of Potomac Interceptor Length
11 Tunnel Sections
2 River Tunnel Crossings
36-96 Inches Diameter Pipe Size
Contact Information
Potomacinterceptor@dcwater.com
202-787-4096
