CFA 21/APR/22-3

HPA number

Various properties owned by U.S. government or District of Columbia
Washington, DC
United States

DC Water
National Park Service
Potomac River Tunnel Project
Construction of six combined sewer outflow facilities
Review Type


Dear Ms. Hall:

In its public meeting of 21 April conducted by videoconference, the Commission of Fine Arts approved, based on its prior review of the submission materials, the final design for eight combined sewer overflow (CSO) facilities, to be constructed as part of the Potomac River Tunnel component of the DC Clean Rivers Initiative; this includes three facilities within the Old Georgetown historic district, four within Rock Creek and Potomac Parkway and West Potomac Park, and one at Joint Base Anacostia–Bolling. In its approval, the Commission adopted the report of the Old Georgetown Board (enclosed) and recommended that the equipment boxes in all locations be dark gray in color.

Please coordinate the submission of the remaining CSO facility—CSO 29, within the Old Georgetown historic district—with the staff, which is available to assist you.


/s/Thomas E. Luebke, FAIA

Kym A. Hall, Area Director
Region 1–National Capital Area
National Park Service
1100 Ohio Drive, SW
Washington, DC 20242

cc: John Cassidy, Greeley and Hansen
Seth Charde, DC Water

Encl.: Report of the Old Georgetown Board, 21 April 2022


CFA 21/APR/22-2
Various addresses
(Square various, Lot various)
Construction of six combined sewer outfall facilities

REPORT: The applicant, DC Water and the National Park Service, propose the construction of six combined sewer outfalls (CSO) on publicly owned land within the Old Georgetown Historic District, part of a larger undertaking associated with the Potomac Tunnel component of the DC Clean Rivers Initiative. Each outfall consists of many underground elements such as large-diameter pipes, vertical access holes and covers, vent structures, above-grade equipment cabinets, and outlet structures at the water’s edge. For each of the outfalls, a standard design of stone cladding is proposed.

In total, Old Georgetown Board (OGB) will have reviewed submissions of the six outfalls in the historic district only; the rest of the Clean Rivers/Potomac Tunnel scope will be submitted to the Commission of Fine Arts separately for its review. In addition, several of the outfalls (CSOs 025 and 026) were previously approved on Consent by the OGB and CFA because of their relatively minor visibility; one outfall, CSO 029, near the Georgetown University Canal Road entrance, will be presented separately at a later date. At its meeting of 7 April 2022, the OGB reviewed and approved the remaining three (CSOs 024, 027, and 028) with the following comments:

CSO 024: Recommend approval as proposed, noting the appropriateness of the brick enclosure for the vent structure.

CSO 027: Recommended that the above-grade equipment at CSO 027, adjacent to the Whitehurst Freeway and the Georgetown Waterfront Park, be painted dark green.

CSO 028: Recommend further development of the contours and vegetation around the rough stone- clad vent structure situated within the landscape in order to reduce its visual prominence from pedestrians on the adjacent Capital Crescent Trail.

Lastly, the OGB noted that the project was impressive in terms of its scale, complexity, and use of technical innovation. Because of this, the OGB recommended the applicant consider providing interpretation of the project at locations where above-grade infrastructure will be built, for public education and interest.

RECOMMENDATION: NO OBJECTION to the construction of the combined sewer outfalls (CSOs) 024–028, as part of the Potomac River Tunnel Alignment, to include an outfall, vent structures, mechanical and electrical equipment, and associated landscape changes, per materials received 16 April 2022. Recommend the implementation of a system of interpretation for the Clean Rivers Initiative for these locations and revisions to the design of CSOs 027 and 028 as noted above.