CSO 021 Diversion Facilities Project

CSO 021


The CSO 021 Diversion Facilities projects consist of the construction of a structure to divert flows from the existing Combined Sewer Overflow (CSO) 021 outfall, the largest CSO on the Potomac River. In order to minimize future impacts, the project was constructed simultaneously alongside the ongoing Expansion Project at the John F. Kennedy Center for the Performing Arts. The diversion structure will ultimately be connected to the future Potomac River Tunnel, which will convey the diverted flows to the Blue Plains Advanced Wastewater Treatment Plant for treatment prior to discharge to the Potomac River.

Scope of work

  • Construction of a new diversion chamber to divert flow from the existing CSO 021 Outfall Sewer to the future Potomac River Tunnel
  • Construction of a shaft to drop captured flows to the future Potomac River Tunnel
  • Construction of a ventilation control facility to regulate airflow in the tunnel system
  • Coordination with the Kennedy Center Expansion Project to ensure compatibility of surface features (manhole openings, equipment pads, etc.) with site improvements and minimization of future impacts related to construction and commissioning of the future Potomac River Tunnel


DC Water worked closely with multiple stakeholders to provide timely information about the project, to solicit input, and to ease the burdens of construction. These stakeholders include the Kennedy Center, NPS, District Department of Transportation, and Department of Energy & Environment. DC Water also coordinated with the Advisory Neighborhood Commission to provide regular updates.

Project Location