D.C. Water said substantial progress has been made in its efforts to contain a major sewer overflow that began after a 72-inch section of the Potomac Interceptor collapsed one week ago along Clara Barton Parkway.
The collapse triggered a significant sanitary sewer overflow into the C&O Canal National Historical Park.
The Potomac Interceptor is a 54‑mile sewer line that carries roughly 60 million gallons of wastewater a day from communities near Dulles International Airport, Loudoun and Fairfax counties, the towns of Vienna and Herndon, and parts of Montgomery County to the Blue Plains Advanced Wastewater Treatment Plant in the District.
In the days after the Jan. 19 failure, crews assisted by the National Park Service worked nonstop to clear access, install pipes and build a temporary bypass system. The system is designed to divert wastewater upstream of the collapse, route it through a dry stretch of the C&O Canal and return it to the sewer line downstream.
D.C. Water said the bypass became operational Wednesday night. Six large pumps are now moving wastewater around the damaged section, and flow returning to the sewer system has increased by about 40 million gallons per day.
Some wastewater is still escaping near the break, which D.C. Water said is expected while the collapsed pipe continues to drain. Additional pumps are being brought in to help reach full containment.
With the bypass running, D.C. Water said crews will begin excavating and inspecting the collapsed pipe segment, removing debris, stabilizing the surrounding ground and developing a long‑term repair plan. The utility has not yet said how long permanent fixes will take.
The collapse caused wastewater to spill into a creek bed that leads to the Potomac River. D.C. Water said once repairs are complete, the agency and its partners, including the National Park Service and the Maryland Department of the Environment, will survey affected areas for erosion, debris removal and any environmental cleanup.
D.C. Water said drinking water remains safe and unaffected. The District’s drinking water system is separate from its wastewater system, and the overflow occurred downstream of the Washington Aqueduct’s intake points. Intake structures at Little Falls were also closed as a precaution.
The collapse occurred just east of the Interstate 495 interchange along Clara Barton Parkway and initially forced the closure of the right inbound lane.
The public is asked to avoid posted areas along the canal or river. Anyone with questions can contact D.C. Water at 202‑354‑3600 or its 24‑Hour Command Center at 202‑612‑3400.
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