Excavation is underway to access a damaged section of the Potomac Interceptor, a major sewer line that collapsed on January 19, along Clara Barton Parkway near the 495-interchange and C & O National Historical Park in Montgomery County, MD. This marks a pivotal step forward in the recovery process, allowing DC Water and its contractor to directly inspect the damaged pipe, exposing the affected section to assess its condition and formulate the best possible repair strategy.

A bypass system activated this weekend continues to successfully divert wastewater back into the sewer line further downstream of the collapse site.  Engineers on-site report the lowest level of overflow from the area around the collapse since the incident started allowing the excavation activities to begin.

While still in the early stages of excavation, the site is stabilized with work progressing as a high priority repair. The focus over the next few days is to safely reach the break location to remove debris and collapsed material blocking the sewer line. This is vital to restoring the system’s functionality and eliminate dry and wet weather overflows. Preliminarily, engineers will be evaluating whether they can remove the crown of the damaged section of pipe, allowing the flow to go downstream through the pipe, fully contain the overflow, and reduce reliance on temporary pumping.

Repairing the pipe will be a complex and timely process, given the size of the 72-inch diameter sewer line and the volume of wastewater flow. Until the damaged pipe is inspected, the timeline for the repair cannot be determined. Engineers are exploring whether they can fix the broken pipe using 50 feet of 72-inch pipe from a previous project just completed upstream. This could potentially expedite the repairs.  

Two additional pumps began operating today to support the bypass pump operations. This is in addition to the six industrial sized pumps that have been working since Saturday – each with a capacity to pump seven million gallons a day. The additional pumps will provide more pumping capacity and redundancy when pumps need to be taken out of service for cleaning and maintenance.

While a small volume of wastewater is still escaping, the bypass has greatly minimized overflows, with no overflow reported for more than ten hours today. During peak periods when people wake up and return home from work and school demand may increase. This can cause some temporary overflow which is being monitored closely around the clock. Additionally, given the volume of the overflow over the past week it will take time to fully drain the creek bed and stop the flow into the Potomac – even with full containment.

Once the damaged pipe section is excavated, contractors will work to install trench boxes for shoring – acting as giant retaining walls – to contain the flow while repairs are being made.

Since the collapse occurred, DC Water has been working closely with federal, state and local partners, including the U.S. Environmental Protection Agency (EPA), National Park Service, U.S. Coast Guard, Washington Aqueduct, District Department of Energy and Environment (DOEE), DC Homeland Security and Emergency Management Agency, Maryland Department of the Environment, and the Montgomery County, Fairfax County and Loudoun County governments. Together, we are coordinating efforts to contain the overflow, monitor and assess environmental impacts, and keep the public informed.

DC Water continues to remind the public to follow all warning signs, avoid contact with sewer overflows, and keep pets away. Anyone who comes in contact with wastewater should wash exposed skin immediately, disinfect shoes or other items, and seek medical attention in the event of illness.

If you have any questions or need additional information contact DC Water’s Customer Care team at (202) 354-3600 (Monday–Friday, 8 a.m. to 5 p.m.) or the 24-Hour Command Center at (202) 612-3400.