Infrastructure Integrity

Related search terms from www.waterinfolink.com: acoustic monitoring, AMI, leak detection

There is a tremendous need to invest in and upgrade America’s drinking water infrastructure. According to a 2007 U.S. Environmental Protection Agency survey, the 20-year capital investment need for public water systems is about $335 billion. The American Society of Civil Engineering reports that each day approximately 7 billion gal of treated drinking water is “lost,” primarily due to leaks in drinking water pipeline throughout the U.S.

It is essential that water utilities reduce this lost supply not only because it is increasingly scarce but also because of its embedded energy and the greenhouse gas footprint that it represents. American Water is responsible for more than 45,000 miles of main, so this is an important issue for the company.

American Water has been working with various companies to develop and test new low-cost acoustic leak detectors using advanced metering infrastructure (AMI) systems. By deploying these technologies throughout distribution systems, water utilities are able to survey for pipeline leaks every day. The acoustic monitors, whether installed on the service line or in the distribution system, can relay the data back to system operators using an analytical software package. The software processes the data and alerts the system operator when a monitor is detecting a “noise” indicative of a leak.

Testing New Technology

American Water’s pilot study of the system in Connellsville, Pa., which used Itron’s MLOG leak detector and an AMI system by Aclara, was successful, reducing the lost water by almost half from more than 25% within six months. This saved an estimated $140,000 in lost revenue, with a payback for the installed technology of less than two years. The addition of acoustic monitoring helped justify the investment of the fixed-network AMI that now conveys daily meter readings to the utility. With funding from the Water Research Foundation, the Connellsville project has been analyzed over three years during which the value of the technology has been demonstrated. A report on the project will be published later this year.

A second fixed network system using the MLOG has been operating in the New Jersey American Water system in Irvington, N.J., serving 9,000 customers using an Itron fixed network. An adjoining system also may be equipped with the Itron technology later this year.

This year, West Virginia American Water will deploy FCS Permalogs that are part of a Datamatic mesh network AMI system, eliminating the need for drive-by reading for an area serving about 12,000 customers. The project, funded by federal stimulus money, also will provide daily meter reads and daily data about pipe noise gathered from the monitors.

In the Valley View system in Illinois American Water’s Metro Chicago district, a pilot program employing Gutermann’s Zonescan acoustic monitors is being combined with an AMI system provided by Aclara. This system is designed to enable the system operator to instruct adjacent units to correlate around a suspicious leak noise. If successful, the system will be able to differentiate between leak noise and extraneous noise and point out the leak location along the pipe.

American Water continues to deploy the drive-by option for acoustic monitors. In California American Water’s Monterey system, 4,100 MLOGs are in place. Many of the utility’s vehicles are equipped with collectors that gather data, which is stored for up to 11 days. The software allows the operators to see if any areas have been missed during the month to be sure that recent data is collected.

Determining Value & Prevention Tactics

Coupled with the demonstrations of the acoustic monitoring technology are economic tools that allow systems to evaluate the potential of AMI and acoustic monitoring. Cost models for AMI and acoustic monitoring have been made available to all American Water state operations. This allows each system to assess costs and benefits of mobile AMR and mesh or fixed- network AMI with or without acoustic monitoring.

As suggested by economic analysis, the value of the continuous acoustic monitoring systems is most significant where cost of water is high and supply is limited. The type and frequency of leaks are also important. In many locations, leaks that are small and run undetected for significant periods make up most of a system’s leakage, and this is what the acoustic monitor will identify.

The acoustic monitoring analysis has done more than just detect leaks; some significant insights into the time it takes leaks to surface, the condition of the pipe and possible triggers for failures are being revealed. Approximately two-thirds of the main breaks in Connellsville that ran a full overnight period in the range of a working MLOG provided some acoustic clue before they were repaired. About half of these leaks were repaired before they surfaced. Repair cost analysis suggests that rapid detection and repair of the failing main can reduce the cost of repair and likely prevent additional collateral damage and overtime costs.

Because the monitors detect when a leak first starts rather than when the leak appears, it may be possible to determine what factors contribute to the start of the leak. This will be an area of further study as American Water continues to seek better ways to reduce water loss.

David M. Hughes, P.E., is lead infrastructure engineer for American Water. Hughes can be reached at 856.346.8320 or by e-mail at david.hughes@amwater.com.

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