Design of a Physical and Electronic Inspection of a 66-Inch (168-cm) Steel Water Main in Washington, DC

The low service area of the District of Columbia Water and Sewer Authority’s (DC Water) water distribution system provides water to the downtown area of the city (including federal buildings and the White House) and is the source for pumped water to three higher pressure zones. As part of DC Water’s asset management program, one particular element of the low service transmission system was identified as needing attention. This is an 8,000 foot (2,450 m) section of large diameter 66-inch (168 cm) welded steel water transmission main in the northeast section of Washington, DC. The pipe was constructed in the 1960s with an internal and external coal-tar enamel coating, and a portion was equipped with a sacrificial buried anode cathodic protection system. However, the pipeline has never been taken out of service and dewatered for inspection. The purpose of the project is to perform a manned entry of the pipeline for internal inspection of the joints and walls by visual, physical and electronic testing.