Project Links
2026 - Repair high priority section of Potomac Interceptor near Little Falls Branch (MD/DC Line)
Chesapeake and Ohio Canal National Historical Park » 2026 - Repair high priority section of Potomac Interceptor near Little Falls Branch (MD/DC Line)
The Potomac Interceptor (PI) sanitary sewer system includes a significant portion of its length within the Chesapeake and Ohio Canal National Historical Park in Maryland and Washington, D.C. The system, managed and operated by DC Water, was constructed in the 1960s from reinforced concrete pipe. This system, including the municipal sewer systems that feed it, transports sewage from a significant portion of Maryland, northern Virginia, and Washington, D.C. to the Blue Plains wastewater treatment facility. The sewer system enters the park as it crosses the Potomac River just south of Great Falls and parallels the canal, Clara Barton Parkway, and Canal Road until it reaches Georgetown, Washington, D.C.
After recent inspections, DC Water proposes to complete immediate repairs of a short section of this system immediately upstream of the Chain Bridge near the Maryland and Washington, DC boundary. DC Water has identified that this area, falling between the Chain Bridge parking lot and the Little Falls Branch, requires immediate repair. This pipe will be slip-lined with a smaller pipe comprised of fiberglass-reinforced pipe (FRP) or centrifugally cast fiberglass reinforced polymer mortar (CCFRPM).
Near the center of this section, at a bend in the pipeline, DC Water will excavate down to the pipe and install suction piping, powered by a number of pumps, to establish a sewage bypass around the area. Bypass pipes will convey sewage along the road shoulder and will discharge back into the PI below Manhole 4252. After initial geopolymer application in this area, bypass pumps and pipes will then be installed up to Manhole 1.6, near the Little Falls Branch. Construction will necessitate three areas of pipeline excavation and operation of bypass pipes. This entire area of pipeline will then be slip-lined with a smaller-diameter pipe.
Areas of equipment access, materials staging, excavation, and bypass pipes will be protected with a layer of geotextile separation fabric, mulch or gravel, and/or construction matting to prevent rutting and facilitate site restoration. Trees, shrubs, and understory plants, mostly consisting of invasive vines, will be removed where necessary to complete repairs, including for bypass piping and excavation areas. Vegetation material will be cut, chipped, and used under construction matting. Material will be removed from the park after the project is complete. The NPS coordinated with US Fish and Wildlife Service on potential impacts to listed species. Because of the urgent nature of needed repairs, the agencies will complete emergency Endangered Species Act consultation and will work with DC Water to incorporate conservation measures during their construction activities. Upon project completion, the NPS will work with DC Water to regrade, restore, and revegetate the site.
All excavation will be completed within the footprint of the existing pipeline so no new ground disturbance will occur. The project will avoid impacting known archeological sites as well as the Little Falls Branch culvert. The project site lies outside of traditional visitor use areas (e.g., the towpath), so no formal area closures will be necessary. Further, a Maintenance of Traffic and safety plan will be developed to ensure vehicle and pedestrian safety during construction. Parking at the Chain Bridge lot will remain open but several of the parking spaces may be taken by construction vehicles and/or equipment.
All work will be performed by DC Water and/or its designee/contractor within the existing DC Water right-of-way. This work will be permitted under NPS Special Use Permit. Questions about the Potomac Interceptor system and planned repair work can be addressed by DC Water: https://www.dcwater.com/potomacinterceptor.
Work is expected to begin with equipment staging during the week of June 1, 2026.
After recent inspections, DC Water proposes to complete immediate repairs of a short section of this system immediately upstream of the Chain Bridge near the Maryland and Washington, DC boundary. DC Water has identified that this area, falling between the Chain Bridge parking lot and the Little Falls Branch, requires immediate repair. This pipe will be slip-lined with a smaller pipe comprised of fiberglass-reinforced pipe (FRP) or centrifugally cast fiberglass reinforced polymer mortar (CCFRPM).
Near the center of this section, at a bend in the pipeline, DC Water will excavate down to the pipe and install suction piping, powered by a number of pumps, to establish a sewage bypass around the area. Bypass pipes will convey sewage along the road shoulder and will discharge back into the PI below Manhole 4252. After initial geopolymer application in this area, bypass pumps and pipes will then be installed up to Manhole 1.6, near the Little Falls Branch. Construction will necessitate three areas of pipeline excavation and operation of bypass pipes. This entire area of pipeline will then be slip-lined with a smaller-diameter pipe.
Areas of equipment access, materials staging, excavation, and bypass pipes will be protected with a layer of geotextile separation fabric, mulch or gravel, and/or construction matting to prevent rutting and facilitate site restoration. Trees, shrubs, and understory plants, mostly consisting of invasive vines, will be removed where necessary to complete repairs, including for bypass piping and excavation areas. Vegetation material will be cut, chipped, and used under construction matting. Material will be removed from the park after the project is complete. The NPS coordinated with US Fish and Wildlife Service on potential impacts to listed species. Because of the urgent nature of needed repairs, the agencies will complete emergency Endangered Species Act consultation and will work with DC Water to incorporate conservation measures during their construction activities. Upon project completion, the NPS will work with DC Water to regrade, restore, and revegetate the site.
All excavation will be completed within the footprint of the existing pipeline so no new ground disturbance will occur. The project will avoid impacting known archeological sites as well as the Little Falls Branch culvert. The project site lies outside of traditional visitor use areas (e.g., the towpath), so no formal area closures will be necessary. Further, a Maintenance of Traffic and safety plan will be developed to ensure vehicle and pedestrian safety during construction. Parking at the Chain Bridge lot will remain open but several of the parking spaces may be taken by construction vehicles and/or equipment.
All work will be performed by DC Water and/or its designee/contractor within the existing DC Water right-of-way. This work will be permitted under NPS Special Use Permit. Questions about the Potomac Interceptor system and planned repair work can be addressed by DC Water: https://www.dcwater.com/potomacinterceptor.
Work is expected to begin with equipment staging during the week of June 1, 2026.