Asset Management: Condition Assessment for Buried Assets

Using acoustic techology, water utilities can gauge distribution systems, prioritize repairs and replacement

 

In order to optimize asset management, it is critically important to understand the condition of components within the system. Given that much of the infrastructure is buried, this hasn’t always been reasonably feasible. Traditional indirect methods factor in age of materials, burst rate and criticality and generate a grade system for prioritizing replacement. It’s an imperfect algorithm. A utility might see incidental problems with certain materials and make the erroneous assumption that those issues represent the pipeline as a whole, only to find out during replacement that the pipeline was in good condition and the problem was isolated.

However, thanks to advances in both leak detection and pipeline assessment, utilities can now include a more complete picture of these buried assets within their solution. With this approach utilities can invest their limited resources more effectively.

Echologics, a division of Mueller Company, makes use of acoustics to measure pipe condition and detect leaks. Placing two sensors on the exterior of the pipe, typically between two valves, an acoustic wave is introduced into the pipe and measured from sensor to sensor. Pipe material softens during degradation, which dampens the waveform. This measurement gives an average condition of that section of pipe. Other indirect measurements, such as soil conductivity and ground current measurement, can be factored into the assessment, providing an even more detailed report.

“If you look at the life of a pipe, it really has three different lives,” articulates Marc Bracken, vice president and general manager at Echologics. “It has a design life, the life that the engineer used during specification. It has the working life, the time that the utility actually keeps the pipe in use. [It has] the economic life—which can be the longest life—the time period where it makes more sense to maintain the asset as needed versus replacement.”

Ultimately utilities need to reconcile the pain of non-revenue water against repair and replacement costs. According to Bracken, a rough rule of thumb for pipeline replacement is a million dollars per mile. However, if you layer on top of this other departments’ scheduled work, such as road resurfacing and sanitary sewer, you get a clearer economic model.

“At the end of the day, utilities need to know the structural condition of the pipe to make sound asset management decisions,” adds Bracken. “Just as importantly, the utility needs to understand the degradation mechanism, factoring this into future material specifications.

Some U.S. utilities are employing a district metering approach to their distribution network. This allows the utility to establish zones, comparing aggregate customer meter data to the data of a large meter that feeds that zone. It can highlight problem areas. Furthermore, this information can be used to prioritize a more thorough assessment and leak location study.

 

cc image Herkie