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Potomac Interceptor Sewer Restoration Project

In partnership with the National Park Service (NPS), the District of Columbia Water and Sewer Authority (DC Water) is proposing to rehabilitate three discontinuous segments (LZ09, LZ03B, and LZ03C) of the Potomac Interceptor (PI) sanitary sewer system located adjacent to the Clara Barton Parkway and within the Chesapeake and Ohio Canal National Historical Park (C&O Canal NHP) between Lock 14 and the Chain Bridge (Figure 01). This project would take place on land administered by the C&O Canal NHP and the George Washington Memorial Parkway (GWMP).

The PI was constructed in the 1960s and conveys roughly 60 million gallons per day of wastewater from Washington Dulles International Airport and local communities to the Potomac Pumping Station in DC. The PI is constructed of reinforced concrete pipe (RCP) ranging from 72 to 96 inches in diameter. Pipeline inspection has found RCP deterioration within the three segments. Over time, if not renewed, extensive RCP deterioration could result in the release of raw sewage to the environment.

DC Water will work with NPS to identify appropriate rehabilitation methods that avoid, minimize, and mitigate potential environmental impacts that may result from the proposed project. Proposed rehabilitation methods may necessitate bypass piping, routed on the ground surface along the parks, to accept existing sewage flow during repairs in addition to the construction and maintenance of new manholes for access.

The rehabilitation of these pipeline segments would occur consecutively. Construction activities would begin on the LZ09 segment and would last for approximately 18 months. Work would then occur on the LZ03B segment which would last for approximately 14 months. Repairs to the LZ03C would then begin, lasting approximately 9 months.


For More Info

Find out more about this project at: 


Request For Public Comments

Interested members of the public can submit comments or concerns to: or
ATTN: Potomac Interceptor Rehabilitation Scoping Comments
National Park Service
C&O Canal National Historical Park
142 West Potomac Street Williamsport, MD 21795

Comments must be submitted online or postmarked by July 1, 2022 to receive consideration.

We look forward to your participation and appreciate your feedback on this project which is necessary to extend the life of vital regional infrastructure and to avoid water quality impacts to the C&O Canal and the Potomac River