California Utilities Assess Pipelines Leak Gas Pockets
To protect a thriving economy, Californian water utilities require a reliable and predictable supply of clean water; any water lost through leaks not only threatens the ability to provide adequate service, but also represents the waste of a scarce resource.
In order to ensure reliable service delivery and reduce Non-Revenue Water (NRW) – which can be defined as water that is produced for consumption and lost before it reaches the customer – two Californian utilities completed leak detection surveys on their critical water transmission mains in December 2013, while a third utility assessed a force main with a suspected leak.
While reducing NRW can be challenging, one of the most effective methods in reduction is having a well-developed leak detection program for both small- and large-diameter water mains. For large-diameter pipes, the most effective method of identifying leaks is through the use of inline leak detection. This method brings the leak detection sensor directly to the source of the leak, which provides the highest level of accuracy.
Accurately locating and repairing leaks on large-diameter mains is the best way to reduce NRW through leak detection, as almost 50 percent of the water lost through leaks is through large-diameter assets. Identifying leaks also increases service reliability and reduces the likelihood of a pipeline failure, as the presence of leaks is often a preliminary indication of a failure location.
In December 2013, the Los Angeles Department of Water and Power (LADWP) completed an inline leak detection survey on 8 miles of the 45-mile Second Los Angeles Aqueduct, which is made of 76-inch mortar-lined steel.
Identifying leaks on metallic pipe materials is particularly important for water utilities, since leakage is a main indicator that metallic pipes will eventually fail. LADWP’s inspection using SmartBall® leak detection confirmed that this section of the aqueduct is leak-free.
Although addressing NRW is a major priority for utilities, operators of wastewater force mains should also be concerned with leakage. Leaks or failures on wastewater pipelines can have a devastating effect on the environment and can lead to litigation and consent decrees. In addition, gas pockets in force mains are of significant concern as hydrogen sulfide gas within the wastewater can be converted to sulfuric acid by bacteria in the slime layer on the pipe wall, which may cause corrosion and eventual breakdown of the pipe’s exposed surface.
In order to conduct a leak and gas pocket screen on an 18-inch force main, the Vallejo Sanitation and Flood Control District completed a 1.3-mile survey using SmartBall technology. The inspection identified three acoustic anomalies that were associated with pockets of trapped gas.
Through the inline assessment of this force main, the District was able to identify areas of potential concern, which will focus resources and guide future investigations.
Highly accurate inline leak detection systems that can detect leaks and gas pockets in operational pipelines. These systems are used primarily on larger diameter water and wastewater transmission mains of all materials as well as oil & gas pipelines.