Washington Suburban Sanitary Commission Installs a 70-mile Acoustic Fiber Optic Sensing System
The Washington Suburban Sanitary Commission water distribution system is the largest water and wastewater utility in the nation, with a network of 5,600 miles of fresh water pipeline and 5,400 miles of sewer pipeline in and around our nation’s capitol. Within that network is an extensive number of prestressed concrete cylinder pipe (PCCP) transmission mains. These pipes are manufactured with concrete and reinforced with steel wire bands, and corrosion can cause gradual deterioration of the wires.
In recent years, WSSC has inspected these pipes, and when necessary, replaced corroded sections. Inspections of the PCCP are on the pace of 12 to 18 miles per year since 2012. This program is continuing on pipes of 48 inches or larger, and will be expanded to all 36-inch and 42-inch pipe.
To balance this inspection, and combat the devastating impacts of a broken main of this size, WSSC has been adding Acoustic Fiber Optics (AFO) to detect the sounds associated with prestressed wire breaks on PCCP sections while the pipelines are in service. The AFO system continuously monitors the integrity of all the pipes and provides notification if a potential problem is detected in any pipe section.
Progress in the Pipe
The AFO cable network covers 71 miles of WSSC’s 77 miles of PCCP water transmission mains 48 inches and larger. The continuous AFO-monitoring technology provides a new level of peace of mind for the utility to know that they’re doing their best for customers. Because the design of the pipe, AFO is effective only for PCCP, not for other types of pipe in the system such as ductile iron or cast iron.
As aging infrastructure continues on a path of fixing what breaks, it’s great to see a far-forward utility that has taken monitoring to the next level to ensure continuity of service and to avoid catastrophe.
View this video of the installation of the network and discussions of repair work: