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Emergency work will begin June 15 on a deteriorating stretch of the Potomac Interceptor sewer line near Potomac, Maryland, where a failure could threaten drinking water intakes serving Maryland and Washington, D.C.
Crews will rehabilitate 1,700 linear feet of the sewer at Muddy Branch near Pennyfield Lock, also known as Lock 22 on the C&O Canal. Inspections uncovered serious corrosion, exposed reinforcing steel and other structural damage requiring immediate attention.
The work follows the Jan. 19 failure of another section of the 54-mile interceptor, which released approximately 240 million gallons of wastewater into the Potomac River. That spill occurred along Clara Barton Parkway inside the Beltway, downstream from the principal drinking water intakes used by WSSC Water, the Washington Aqueduct and Fairfax Water.
A rupture at the upcoming repair site would pose a greater risk because it is near the Maryland and D.C. drinking water intakes.
The pipe’s most damaged portion is completely encased in concrete, reducing the likelihood of failure. Other sections have also been reinforced with a protective concrete cap.
D.C. Water notified WSSC Water in mid-April that the deterioration required high-priority emergency repairs and has continued briefing the utility. Crews are visually inspecting the site twice a week and installing equipment designed to detect flow changes that could indicate a leak or structural failure.
Chief Operating Officer Matt Brown said the utility moved quickly to begin monitoring the damaged section, establish protective measures and accelerate repairs. He said D.C. Water is coordinating with its partners to reduce risks to public water supplies, health and the environment.
Tree trimming and brush removal have already started. Construction is expected to continue through the end of September 2026.
During the rehabilitation, D.C. Water will construct an above-ground pipeline and pumping system to divert wastewater around the work zone before returning it to the interceptor.