DC Water advances bypass efforts after Potomac Interceptor collapse

DC Water and its contractor are advancing efforts to contain a sewer overflow caused by the collapse of a section of the Potomac Interceptor, a major 72-inch sanitary sewer running along Clara Barton Parkway near Interstate 495 in Montgomery County, Maryland.

Crews are mobilizing equipment, clearing debris and installing temporary piping to bypass wastewater flow around the damaged section. DC Water expects high-capacity industrial pumps to begin redirecting some of the flow as early as this weekend, which would significantly reduce the volume of untreated wastewater entering the Potomac River. The interceptor typically conveys up to 60 million gallons of wastewater per day to the Blue Plains Advanced Wastewater Treatment Plant.

The bypass plan involves using multiple pumps, each capable of moving about 7 million gallons per day, to reroute wastewater into a section of the C&O Canal, where it can be contained and reintroduced into the sewer system downstream. In coordination with the National Park Service, crews will remove upper lock gates at several canal locks to accommodate the temporary flow while minimizing impacts to the historic infrastructure.

A partial bypass is expected to be operational this weekend, with full containment anticipated later next week. Once the bypass is fully in place, crews will excavate and inspect the failed section of pipe to determine repair options. The Potomac Interceptor collapse occurred earlier this week along the 54-mile sewer line, which serves portions of Maryland and Virginia.

DC Water noted the incident underscores the need for its ongoing rehabilitation of the Potomac Interceptor, a 10-year, $625 million capital program targeting the system’s most vulnerable sections, some of which are more than 60 years old. In the meantime, the utility continues to coordinate with federal, state and local agencies to protect public health and monitor environmental impacts while repair planning moves forward.