Potomac Interceptor Event

Corrosion, Collapse, and Clean-Up" Examining the Potomac Interceptor Collapse

TESTIMONY OF EDWARD WENSCHHOF, ACTING SUPERINTENDENT, CHESAPEAKE AND OHIO CANAL NATIONAL HISTORICAL PARK, NATIONAL PARK SERVICE, U.S. DEPARTMENT OF THE INTERIOR, BEFORE THE HOUSE ENERGY AND COMMERCE SUBCOMMITTEE ON OVERSIGHT AND INVESTIGATIONS REGARDING THE POTOMAC INTERCEPTOR.

May 20, 2026

Chairman Joyce, Ranking Member Clarke, and members of the Subcommittee, thank you for the opportunity to discuss the recent break in the Potomac Interceptor sanitary sewer system and the Department of the Interior’s response.

The Chesapeake and Ohio Canal National Historical Park (Park) contains within its legislated boundary a significant stretch of the Potomac Interceptor, managed by the District of Columbia Water and Sewer Authority (DC Water). Constructed in the 1960s, the pipeline ranges up to 92 inches in diameter and conveys up to 60 million gallons of wastewater per day to the District of Columbia’s Blue Plains wastewater treatment facility.

The presence of DC Water infrastructure on land administered by the National Park Service (NPS) is not unique to the Chesapeake and Ohio Canal National Historical Park. Due to the age of the city’s infrastructure, a substantial portion of the system lies beneath parkland throughout the District. The NPS has been working closely with DC Water on major initiatives, including the now-completed Anacostia River Tunnel Project and the Clean Rivers Project, which spans three separate national park units and includes multiple combined sewage overflow projects within Rock Creek Park.

On January 19, 2026, Park staff received notification of an active sewage overflow within Park boundaries near the Interstate-495 crossing in Montgomery County, Maryland. The overflow affected an eastbound lane of the Clara Barton Parkway and flowed through parkland, exiting via the historic Rock Run masonry culvert and into the Potomac River.

To mitigate further impacts, the NPS permitted DC Water to use a section of the C&O Canal to bypass the collapsed pipe and convey wastewater 0.4 miles downstream where it then flowed back into the Potomac Interceptor. DC Water started using the canal to bypass the break on January 24, 2026. DC Water completed temporary repairs, removed bypass pumps, and returned full wastewater flow to the Potomac Interceptor system on March 14, 2026.

Following the interim repair, the NPS, DC Water, the U.S. Army Corps of Engineers, and the U.S. Environmental Protection Agency initiated remediation across four defined areas: the stormwater channel, the Rock Run stream and culvert, the Potomac River shoreline, and the canal prism from Lock 14 to Lock 10. Remediation is complete in the first three areas and continues in the canal prism. Crews removed contaminated soils in the prism down to the clay liner, and deeper in some sections where additional contamination was visible. Work crews are removing soil with hand tools from within the locks and using soap, water, and bristle brushes to scrub and clean historic masonry.

Once remediation is complete, the NPS will work with DC Water on long-term restoration, including replanting trees, shrubs, and understory vegetation, as well as restoring a threatened plant species. For resources that cannot be restored, the NPS can seek response costs and damages under 54 USC §§ 100721-100725. We will pursue cost recovery under the special use permit for monitoring and response efforts.

The NPS will continue coordinating with DC Water on long-term repair and rehabilitation of the portion of the Potomac Interceptor system located within the legislated boundaries of the Park.

Mr. Chairman, this concludes my testimony. I am happy to answer any questions that you or the other members of the Subcommittee may have.