90” Brick Rehabilitation - 401 M Street - Waterfront Mall Washington, DC - Over 100 Year Old Pipe

Project Location
4th & M Streets, SW, Washington, DC
Construction cost
$819,000 / $1,024/ft.
Construction Start/End
07/2009 - 12/2009


When was it constructed and how long has it been in service:
Put into service in 1906. This 100 year old line conveys storm drainage to the Potomac River. Since a building is to be constructed over the pipe, the District of Columbia Water and Sewer Authority (DCWASA) required it to be structurally rehabilitated.

Diameter of line, sewer pipe material (RCP, MCIP, brick, etc.), length of rehab portion: 90", Brick (3 layers), 800 feet of rehab plus 90” Brick below spring line and Unreinforced Concrete above spring line.

Depth of pipe:
22 feet
Depth of ground water:
Below pipe due to extensive dewatering on site for other building construction.
Health and safety:
Used conventional confined space entry program.
Has any re-inspection been performed? What was the condition of the pipe?
None yet performed.

​​​​​​​Mike Barnes
District of Columbia Water and Sewer Authority (DCWASA)
Telephone; 202-787-4125
Chad Sargent
Clark Construction
Telephone: 202-479-6850 


Ventilation and odor control used:
Introduced fresh air into pipe past downstream plug through downstream and mid-point manholes by exhausting air from upstream manhole.
Rehab method used:
Danby Panel Lok III-E spiral wound into the pipe with a finished diameter of 84” with full annulus grouting with cementitious grout with minimum compressive strength of 6,000 psi.
Cleaning method used (if required) and who cleaned the line:
High pressure (6,000 psi) water blasting performed by Danby installer, Boyer, Inc.
Method of flow bypass or diversion, if used:
Downstream inflatable plug to prevent backflow from tidal influenced river outlet and upstream sand bag weir with 2” submersible electric pump to bypass small base flow. During storm events, sewer was evacuated and downstream plug was deflated.


Problems encountered during construction:
Heavy rains delayed work progress, curves in pipeline and large manhole with spring line shelves required customizing panel installation. Large diameter required greater care in grouting to avoid deforming liner (no separate bracing was used to support liner). Cement and fly ash supplier had QC problems in his plant which necessitated removal and replacement of substandard grout. Material supplier changed.
Problems encountered after construction: