21st Century Technology
Innovation transforms leak detection.
By Lyn Corum
“The new technologies are automating data collection and the correlation process without field activities. This is reducing the time and expense of labor, equipment, and transportation costs. This is a big deal to utilities.”
–Dean Slejko, Water Products Manager, Aclara
From Pitometers to magnetic pod loggers, leak detection has been transformed in the past decade by new technologies so much so that non-revenue water loss can now be detected and repairs scheduled without the utility technician leaving his or her office computer.
George F. Deacon, in 1873, devised the first recording meter for water waste surveys and introduced the system of district inspections in Liverpool, England. Later, the meter found its way to Boston, MA, for use there. In 1895, wishing to create a more efficient method, Edward S. Cole developed the Pitometer based on the Pitot tube principle, a pressure measurement instrument invented in the early 18th century to measure fluid flow velocity and still in use today in a modified form.
By 1931, a photographic recorder had been added, and the Pitometer Water Waste Survey was perfected by The Pitometer Associates & Engineers in New York. It used the basic water leak detection techniques in use today, which have been updated by the technologies developed this decade, and particularly in the past two to three years. These new technologies have made the job of detecting water leaks in municipal water distribution systems dramatically easier and less costly.
The services and methodology pioneered by Pitometer Associates, which was founded in 1895 are still alive and well today at ADS Environmental Services. ADS Environmental Services is a division of ADS LLC, which is an IDEX Water & Wastewater Business. As described in a 1931 publication by the company, a Pitometer rod is attached to a 1-inch “corporation cock” set on a tap in the distribution line without shutting off the pressure to measure flows and pressure in the line. If a tap and valve is not already available it can be made, and the Pitometer rod is inserted through the tap.
According to Luis Mijares, senior business development manager at ADS Environmental Services, a division of ADS LLC, a Pitometer Computer Recorder (PCR) is then connected to the Pitometer rod and reads differential pressures from the rod, converting them to velocity readings at programmed intervals to capture work day and weekend flow rate readings for later downloading. The PCR is water proof, battery-powered and designed to be left in a manhole or other field enclosure during the flow study.
The Importance of Audits
The importance of tracking water waste, or non-revenue water loss as it is identified today, was recognized in 1931 by Pitometer Associates as a cost controller: “In plants where it is necessary to pump water to the distribution mains, the importance of keeping the daily amount required to a minimum is readily apparent, as the saving in fuel alone soon totals an amount sufficient to pay for the cost of a survey in a short time.”
Today, Doug McCall, director of marketing at Sensus, which developed the AquaSense Advanced Metering Infrastructure (AMI) communications network, says when he started researching the state of leaks in the US and Canada, he found that anywhere from 10 to 45% of water delivered to a utility is pumped back into the ground. “It makes too much business sense to ignore water loss,” he says. But there is a real void of hard data because utilities don’t measure water loss accurately, he adds.
Slejko, water products manager at Aclara says, “Utilities in general are getting more cognizant that lost pumped water means reduced revenues. They are looking to be more efficient in delivering water and being more cost efficient,” he says. What’s driving their newfound interest are water shortages caused by droughts and an aging infrastructure with old, brittle, leaking pipes, he explains.
The American Water Works Association (AWWA) has developed water audit software based on Microsoft Excel spreadsheets. Users key in data on water coming into the system (raw and treated), water production, and metered billing and sales. The output focuses on the dollar value of “apparent” or retail losses, primarily from poorly calibrated meters, unauthorized consumption, and billing errors and physical losses through leaks or overflows in the transmission and distribution system.
Craig Hannah, development manager for the water technology team at Johnson Controls, says audits are a useful tool for directing us to uneconomic water loss. The company recommends that utilities perform AWWA’s water audits annually as a standard business practice. Johnson Controls will also conduct the audits for clients.
An audit helps the utility understand its water balance with the ultimate goal of reducing the volume of non-revenue water and to benchmark its performance to other utilities of the same size. It is useful in determining the volume of real and apparent water loss and their respective costs.
By focusing on reducing lost water that has been pumped and treated, lost revenue can be recovered, Hannah says. Less water is withdrawn, infrastructure capacity is maintained and operating costs are lowered. Since distribution line breaks can be devastating, testing pipelines early and regularly can avoid infrastructure damage.
Advancing the Audit Process
Cityworks, an Azteca Systems Inc. group, has created GIS-based software for use by municipalities for all kinds of asset management applications such as tracking service requests, work orders and associated equipment, labor, and materials. According to Dave Bramwell, Cityworks senior account manager, the company works with consultants who provide the software and other services to municipalities.
Mark Nelson, vice president, and Brett Goodman, water resources department manager, are with Jones Edmunds & Associates, one of the consulting firms working with Cityworks. They are consulting with numerous state and local government agencies to implement Cityworks software to track, monitor, and report on both supply and demand-side programs, which includes water conservation.
One of the agencies Jones Edmunds is working with is the St. Johns River Water Management District, a state agency in Florida responsible for supplying water to central and north Florida. The district has been proactive in recognizing the need to give utilities credit for conserving water, which had not been encouraged in the past. It provides grants to utilities to implement asset and work management solutions like the Cityworks software platform to accomplish these goals.
Jones Edmunds has also been working with St. Johns County Utilities and the City of Sanford whose water supplies are regulated by the St. Johns River Water Management District, to help reduce non-revenue water and better track, monitor, and report on their water conservation projects, costs, and benefits using the Cityworks software.
Goodman says the concept is still in its infancy phase since it is difficult to track utility practices. They began with using the Cityworks software platform to track billing information coming from the advanced meter reading (AMR) system and flag accounts that looked funny. The utility could then interface with the customer and resolve the problem if it exists.
Moving on to a more complex tracking, Nelson explains that to design a water conservation program, they analyzed several years of account data from a few utilities along several parameters. But they soon realized that to track conservation programs and to expand them, the utilities would have to use an auditing tool to identify the amount of non-revenue water that was lost in order to justify what is saved through conservation. For example, if soil moisture sensors are used in a conservation program and the sensors break with no notice, the conservation measure will fail to produce savings.
As water demand goes down, leaks become a higher percentage of the water service, Nelson says, and detection becomes critical. “People have to do more with less, and the Cityworks software has given us better tools to find the leaks,” he says.
A leak detection company working for a utility, or a utility’s own leak detection staff, can feed the results—the number of leaks found— into the software platform, a service request can be produced automatically for the line manager and prioritized. “This reduces time and increases accountability,” says Nelson.
AMI Enters the Scene
Partnering leak detection sensors with AMI is relatively new and several companies have done just that to offer products that integrate fixed network AMI and AMR technologies with leak detection equipment. Hannah, with Johnson Controls, says the most recent development is Itron’s fixed network ChoiceConnect AMR/AMI data collection system that can collect data from its leak detection sensors.
As water demand goes down, leaks become a higher percentage of the water service.
Itron leak sensors are attached to a service line immediately upstream of the water meter, and the leak sensors record vibrations on the service lines and use the Itron 100-W ERT radio to transmit the data. A battery powers both the leak sensor and AMR/AMI system radio.
The technology is effective, says Hannah, but the utility must have the discipline and resources to use it. It is very effective in metallic distribution systems, but their effectiveness is diminished in nonmetallic pipes, which dampen vibrations. In metallic pipe, the vibration waves can propagate up to a thousand feet, but the vibrations can only travel between 500 feet and 700 feet in non-metallic pipe. Unless you have sensors deployed every 500 feet, you will have gaps, he says.
Aclara, part of the Utility Solutions Group of ESCO Technologies, has merged its STAR Network two-way fixed-network AMI technology with Gutermann International’s acoustic correlating loggers and Web-based ZoneScan net software to create the STAR ZoneScan automated leak detection system. Aclara introduced the new system in January.
Slejko, the water products manager at Aclara, explains that the original STAR Network is about 15 years old and was the first fixed network for water. The company has made major upgrades to that product in the past two years. The original system was one-way—data were transmitted from the endpoint to the computer when queried. The system is now two-way, and the computer can transmit time-synchronized data requests for hourly feeds at the top of each hour.
STAR ZoneScan, of course, can work in the early hours of the day when background noise is minimal. It works on all types of pipes and can be deployed both temporarily in lift and shift mode and permanently. The loggers attach magnetically to valve stems throughout the distribution system.
The STAR Network can also send information to Gutermann’s acoustic data loggers installed in the distribution system where adjacent loggers record the sounds of a leak simultaneously. Knowing the distance between the loggers and the diameter of the pipe, the sounds are correlated, providing the operator a pinpoint visual of where the sound of the leak originates in the pipe, explains Slejko.
A technician can be sent to within a few feet of the detected leak and using sound correlators they can dig and find the leak quickly. “This is the goal. If you can find the leak quickly before it turns into a catastrophic leak, that’s where a utility can save money,” says Slejko.
This is a big deal to utilities,” he says. Utility employees do not have to drive by to collect logger data, nor do they have to do field correlations with correlators and a couple of sensors on hydrants near loggers. With STAR ZoneScan, he or she can look at the data in the comfort of the office. The new technologies are automating data collection and the correlation process without field activities. This is reducing the time and expense of labor, equipment, and transportation costs, Slejko says.
Leak Detection Software Link to SCADA
Siemens Industry also offers a software package that can link flow meters with computers at a utility’s office. Martin Dingman, in the Industrial Automation Division of Siemens Industry, is responsible for flow products. He describes the SIWA PLAN LEAK software package, introduced in 2010, that ties into existing leak detection and process control systems. SIWA PLAN LEAK can be installed on a commercial PC and will collect data being transmitted from the water distribution system automatically.
A flow transmitter sends the data to a supervisory control and data acquisition (SCADA) system or other device using the SIWA PLAN LEAK software. The software reading the data will identify flow variances after the baseline is established.
Sensus developed its AMI communications network over the past decade as part of its “AquaSense water solution,” according to McCall. In 2009 it was upgraded to a two-way network with patented radio modulators and 20-year warrantied batteries. The network is programmable to open up every 60 seconds. The data are sent to collector antennas, then over high-speed access to a computer.
The radios are attached to acoustic leak detection devices, installed at various points along a distribution line, and connected to the two-way real time network. This opens up an umbrella across all meters, giving the utility the ability to cover the entire water system 24 hours a day, 7 days a week, in real time.
McCall says the most simple pieces of the AquaSense technology can be utilized initially for AMR for billing purposes, then expanded later to more advanced applications, including leak detection and linking to a SCADA system without further investment in the network.
Enigma Combines Loggers and Correlators
ADS introduced a full line of cost-efficient advanced water loss control products in 2009. The “Enigma” is a state-of-the-art, eight-pod digital logging correlation system that can be installed throughout a designated district or pressure zone. It combines leak noise logging and correlation into one operation. Each magnetic pod is attached to a hydrant, valve, or any other appurtenance attached to the pipe. The pods are retrieved after having done their recording and placed in the case that has an infrared “read” port, which reads the sound files from each pod and transfers them to a computer for analysis.
Mijares, business development manager at ADS, says each pod listens for three one-minute intervals set by the user usually with a delay in between. If the same leak type noise is heard over three periods, it indicates a potential leak, and the computer calculates its location. The computer software calculates 23 correlations from the eight pods almost simultaneously.
As an example, Mijares says, if pod #1 and pod #3 both hear the sound, and it has the distance between the two locations, the measured delta time between the sound signatures can identify the distance of the leak from each of the pods. Topside, a technician then measures the distance with a wheel from the subject pod locations and marks the pavement for further analysis with a Mikron ground microphone so as to pinpoint the sound source. If the location cannot be attributed to a service or known water exit point, the pavement is marked for repair crews to dig up and repair the leaky pipe.
Mijares recommends the pods do their work at night in urban environments when street scenes have quieted down and water pressure has increased.
With district measurements, comparing the average daily flows with minimum nightly flow readings for an area can reveal higher-than-expected flows during the hours before dawn. This points out high-leakage areas. The Enigma unit can then be used to find those leaks and by being portable, it can be moved from district to district until the whole service area is covered, says Mijares.
Once the repairs on identified leaks are completed, a permanent AMI system can be installed for ongoing leak noise monitoring. Mijares warns that if a permanent leak detection system is installed before leaks are repaired, the system could adjust to the background noise created by the leaks already there or create a large amount of false alarms until they are all checked out by utility crews. It is best to sweep the system to get rid of leaks before installing a permanent monitoring system.
Mijares says ADS can provide the leak detection equipment or a utility can hire ADS to do the leak detection, or provide leak detection service along side of city crews, train the staff on the equipment, and leave the equipment behind for the utility to use on an ongoing basis.
Mijares cautions that water leak detection is not a one-time thing, but rather an ongoing job. When water pressure goes up after initial leaks are repaired, the next weakest point usually fails. “Pipes will continue to deteriorate over time, so leakage is a reoccurring problem,” he says. If you don’t do district measurements, you don’t know which areas of town should be the focus of the limited find and repair dollars.” Doing complete system sweeps rather than targeted areas wastes valuable time and money conducting leak detection on areas that may not need it.
Echologics’ Work in New Orleans
Hurricane Katrina traumatized New Orleans’ water system, even throwing a pipe or two into treetops. Before the catastrophe, it produced 110 million gallons per day for 400,000 people, says Madeline Goddard, deputy general superintendent at the Sewerage and Water Board of New Orleans (SWBNO), a political subdivision separate from the city. Now, the population is down to 300,000 but the water usage is 135 million gallons per day. The increase is due to water leaks, she says. The goal is to get water usage to below 110 million gallons per day.
The Federal Energy Management Administration (FEMA) is funding the repairs. To date, FEMA has spent $80 million in water pipe repairs, says Goddard. Before Echologics arrived on the scene a year ago, FEMA had paid for 200 permanent data loggers to be installed in the system.
SWBNO has proposed that pipes be replaced and the local FEMA office has agreed, she says. They have together created a replacement protocol, based on number of leaks identified, and the age, type, and diameter of pipes. Final agreement on the plan is now up to FEMA headquarters. FEMA has also funded street restoration, and SWBNO is busy coordinating with the city’s Department of Public Works to replace the pipes as the streets are being repaired. Goddard says FEMA will end its funding of water line replacements when water usage has been reduced by 30 million gallons per day.
Before Echologics was hired, it was difficult to locate exactly where the leaks were because water was leaking out and draining into the water table, which muffled and silenced the noise normally associated with leaks. Goddard says another problem was caused by the high water table—it caused corrosion of the batteries in the loggers.
Echologics is designing a pilot district metering program, says Goddard. It is placing sensors on hydrants every few hundred feet that will be monitored for a brief time. The signals will be interpreted in real time while onsite. Typically, 1 mile of water mains can be surveyed in a single day. This non-invasive work will free up SWBNO staff to perform other work, she says.
When pressure transients were monitored the company discovered pumps were kicking in and out as a result of power outages from the local electrical utility. The 600-plus outages since Hurricane Katrina resulted in the feedwater pumps shutting down suddenly and causing high pressure water to speed through the system creating a “water hammer.” The waves of water that were created could not be seen because they were going out the leaking pipes. The result was while leaks were being repaired the number of new leaks were increasing.
FEMA has agreed to pay to replace the pumps with variable speed pumps to create soft starts and soft stops. They’ve also agreed to replace slow-closing valves. Meanwhile, repairing all the leaks will mean no breaks in the future due to pressure transients, Goddard says.
One mark of success is that the utility can now turn its pumps off at night. Before the leaks were repaired, pumps had to be kept on all night to maintain water pressure, says Marc Bracken, vice president and general manager of Echologics Engineering, a division of Mueller Water Products.
As for the future, Goddard says the utility is running on a shoestring. It used up all its cash to get the system operating after Katrina. Now it is involved in hearings to raise rates.
“We’ve always used leak detection as a tool, and it is part of the discussion with FEMA,” she says.
Lyn Corum is a technical writer specializing in water and energy topics.
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