|A utility professional collects data from a leak noise detector attached to a valve.Photo courtesy of Fluid Conservation Systems and New Braunfels Utilities, Texas.|
Leak detection has proven to be a critical component for the management of water distribution systems, with the goal being not only to conserve water, but also to save energy and money. Pipe leak detection — testing for, finding and repairing leaking pipes — is a major part of ongoing asset management programs for water utilities, especially those with chronic water loss problems. The need for modern leak detection technologies is only expected to grow as the country’s water infrastructure ages and deteriorates. According to the Environmental Protection Agency (EPA), the majority of publicly owned water treatment works in the U.S. were constructed during the 1970s and 1980s. And as drinking water and wastewater systems continue to age, some system components are more than 100 years old.
Risks Associated with Aging Infrastructure and Water Loss
Michael Royer, physical scientist with the EPA, says he expects aging and deteriorating infrastructure is a substantial contributor to water leakage. “Leakage from joints, pin holes, cracks, connections, and valves can be expected to become worse over time due to the cumulative effects of factors such as corrosion, differential settling of soil, traffic loads, water hammer, and temperature,” he says. Leakage depletes water supply, which can cause supply shortages in many areas. In addition, leakage may wash away the pipe bedding leading to loss of support and accelerated failure.
Aging and deteriorating infrastructure can increase main breaks, which cause loss of water service, loss of fire protection, flooding, damage to surrounding infrastructure, damage to homes and businesses, disruption of traffic and business, and response costs. Royer says main breaks can result in contaminants entering the distribution system at the site of the break or through other holes and cracks if the water pressure falls below the water pressure on the exterior of the pipe. According to the EPA, there are 240,000 water main breaks per year in the U.S. The number of breaks increases substantially near the end of the system’s service life. In addition, Royer says holes and joint or appurtenance leaks pose another risk — offering a route for contaminant entry during transient or longer-term low-pressure events.
|The ground microphone amplifies leak noise, allowing workers to identify and pinpoint leaks.
Photo courtesy of Fluid Conservation Systems and New Braunfels Utilities, Texas.
Buying Time with Leak Detection
An obvious solution to control leakage and reduce such risks is to replace old pipes. However, due to lack of funding and limited resources, pipes are often installed beyond their expected lifetime, says Simon Wick, vice president of Water Asset Management at Matchpoint Inc. “Leak detection can assist [with aging pipes], offsetting the time span needed to replace any pipe in the distribution system,” he says. While helping to extend a pipe’s lifespan, the main purpose of leak detection equipment is to determine the position of leaking water pipes within a supply system.
Griff Machinski, a sales manager for Fluid Conservation Systems (FCS), says it is important to realize that leaks visible on the surface represent only a small percentage of leaks underground. “It is very common for leaks to continue for months and even years without ever bringing water above ground. Without modern leak detection equipment, utilities will not have the capability to become aware of the existence of these hidden leaks, much less the ability to actually find and repair them.”
Other Causes of Water Leakage & Loss
There are many causes and variables that contribute to leakage and water loss beyond aging pipes. These may include corrosive soil conditions, pressure variations in the pipe, shifting ground, seasonal ground freezing and thawing, vibration and traffic loads, incorrect backfill, and poor materials, among others. “Resolving these issues can be done through active leak detection efforts, pressure management, and eventually pipe replacement,” says Machinski. Wick says it’s often a combination of such factors, including poor installation, which result in leakage in most distribution networks. “To date, installing the water main at the appropriate depth with suitable backfill has been the best tool to delay leakage,” he says. Pressure Management can also assist in controlling water leakage by lowering the average pressure within the distribution system. “Less pressure equals less stress on the pipe work and less leakage (volume) when a leak does occur,” says Wick. “Pressure management via flow modulation is the most effective application, which has an added benefit of ‘calming’ almost all types of distribution systems [while] ensuring each point achieves at least the minimum pressure required.”
Considerations for Leak Detection Equipment
|There are many reputable companies that offer quality leak detection equipment today, as well as support, training and repair. According to Simon Wick, vice president of Water Asset Management at Matchpoing Inc., general features to consider when choosing and implementing new leak detection equipment are:
Technology advances over the last decade have made the overall effort of leak detection easier, faster, more efficient, and more accurate for the utility operator. Today’s modern leak detection equipment includes devices such as acoustic leak noise loggers, leak detection correlators, ground microphones, environmental data logging systems, and electronic pressure controllers. Noise loggers attach to underground pipe fittings and transmit leak data by radio signals to a receiver. Using conventional telemetry and satellite communication, datalogging systems can record and transmit environmental data such as reservoir levels or pipeline flowrates directly to a computer or mobile device. Electronic pressure controllers automatically adjust pressure levels in underground pipes, preventing pipe bursts and damage to infrastructure.
According to Machinski, equipment is now smaller, lighter, more portable and powerful than in previous generations. “Sensors are more sensitive now to enable finding more difficult leaks,” he says. “Leak noise loggers have evolved to permanently monitor water networks with several choices available for data collection methods and using very little manpower.” Wick says improved sensor technology, improved platforms that allow for use of laptops and handheld PDAs, and the implementation and use of hydrophones are just some of the advances in leak detection equipment over the last few years. Hydrophones are acoustic instruments for detecting or monitoring sound in water.
Royer says the EPA’s Office of Research and Development (ORD), along with the National Risk Management Research Laboratory (NRMRL, epa.gov/nrmrl), has a project underway to investigate new sensor-based water leak detection protocols, methods, and technologies for effective pipe leak detection in drinking water distribution systems. “To develop advanced detection technologies, the research has two central components,” Royer says. “On the one side, research is under way to verify and test leak detection equipment available in the marketplace, such as [the] ZCorr acoustic leak detection system manufactured by FlowMetrix Inc. of Maynard, Mass., and [the] TriCorr system by Fluid Conservation Systems Inc. (FCS). The second research component at EPA is to develop new detection algorithms and methods.”
Leak Detection Advantages/Savings
Wick says that leak detection equipment not only aids in the reduction of non-revenue water (NRW), but in most cases the equipment is “self funding,” i.e., it pays for itself over time with money saved through reducing water loss. Not only is leak detection cost-effective, but Machinski says utilities can also become better and more efficient as a result of building leak detection and prevention measures into their maintenance programs. He cites long-term production cost savings; fewer emergency main breaks, customer service interruptions, and catastrophic failures; and better management decisions, such as repair crew scheduling, street closings, and material needs. Leak detection can ultimately defer production plant expansions and delay the need to find expensive new water sources, he says. (For two real-world examples of what leak-detection equipment can do for utilities, see the sidebar “Case Studies: Leak Detection Paysoff.”)
|Case Studies: Leak Detection Payoffs|
|After establishing a leak-detection and valve-maintenance program in 2009, Texas-based New Braunfels Utilities (NBU) estimates its average water loss at 961 gallons/mile/day, less than half the loss rate during the program’s first year, for a total water loss reduction of 50 percent after two years. NBU used FCS leak detection equipment to conduct scheduled repairs on its pipelines instead of dealing with leaks on an emergency basis. Meanwhile, Birmingham Water Works Board (BWWB) used FCS leak noise loggers to reduce non-revenue water for the city of Birmingham, Ala. by 55 percent in two years. With 4,200 units installed, more than 700 leaks were located between 2004 and 2008.|
Without modern leak detection techniques in place, utilities face losses not only in water, but in money, energy, and resources — money spent unnecessarily to replace pipes too early, money lost due to unforeseen leaks and disruptions, or even increased insurance claims due to big leaks that were not located quickly enough. The loss of water can potentially trickle down to the customers in the form of rate hikes in water bills to compensate for money lost from water leakage.
“We’re always looking at developing new and innovative ways to make the process better,” Machinski says. “Growth and trending is towards more state and/or federal legislation mandating leak detection on water systems. As awareness and need for conservation grows, we expect this market segment to grow exponentially.”
The EPA ORD and the NRMRL are currently cooperating with the Water Environment Research Foundation and Virginia Tech University on a Web-accessible database that will include information on leak detection technologies, among other items. In addition, the EPA says aging water infrastructure is currently one of the top national water program priorities.
Amy W. Richardson is the managing editor of Flow Control magazine. Contact her at ARichardson@GrandViewMedia.com.
For more on leak-detection and water-loss prevention, see “Under Pressure? Strategies for Limiting Leakage & Loss in Water Distribution Systems” (January 2011, pages 16-21).