Acoustic Monitoring and Replacement of a Distressed 42-inch Prestressed Concrete Transmission Main

In 2000, the Howard County Bureau of Engineering implemented an acoustic monitoring program to evaluate the condition of approximately 18 miles of prestressed concrete cylinder pipe (PCCP). Over the last five years, various sections of the prestressed pipe inventory have been monitored for a minimum of three months. The SoundPrint acoustic monitoring system has successfully recorded and located a number of wire breaks along distressed sections of the prestressed inventory, including a portion of the Toll House Road 42-inch transmission main. The increased level of wire breaks recorded along this reach of pipeline led to an emergency pipe replacement program in 2004/05. This paper describes the development, testing, application and results of a continuous acoustic monitoring system used to detect and locate corrosion-induced failures in approximately 6,000 feet of the Toll House and Ridge Rd. 42-inch prestressed concrete pipeline. Also discussed are the results of the acoustic monitoring program and subsequent excavation to confirm deterioration measured by the SoundPrint monitoring system.