Friday, August 31, 2007 in Erosion Control
By Mark Saunders
Drought is a very real problem for the southwest. Less precipitation is falling, and the temperature is rising. In a recent article in the Denver Post, Jonathan Overpeck, director of the Institute for the Study of Planet Earth at the University of Arizona, stated, “The West is warming dramatically. Things are just going to get hotter. You can bet the farm on it.” According to the National Oceanic and Atmospheric Administration, the American West is already 2°F to 3°F hotter than its 100-year annual average. And the US Geological Survey (USGS) is on record stating the western United States is in the middle of a 500-year drought.
This information does not bode well for the desert communities of Las Vegas and El Paso, which receive a very modest 4.13 inches and 8.65 inches of annual precipitation respectively. In addition to warmer temperature and dryer skies, both of these communities are growing at rates that would put a smile on any real estate developer’s face.
Between 1900 and 1990, Las Vegas (Clark County) grew by a whopping 22,480%. And while that pace has slowed somewhat recently, estimates by Clark County Comprehensive Planning put the population at over 2 million by the end of 2007. The Texas Water Resources Institute estimates the population of Texas will double by 2050. El Paso is no exception: The city’s 700,000 residents are expected to morph into 1.4 million in the next four decades.
This combination of a warmer, drier climate with a growing population and its attendant need for more water puts these desert communities in the position of tapping every resource and adopting any technological advantage that allows them to conserve the West’s most-limiting resource.
In addition to common consumer-side conservation efforts such as watering restrictions and programs to encourage the use of low-flush toilets, front-loading clothes washers, low-flow faucet aerators and showerheads, and fixing leaky plumbing, the Las Vegas Valley Water District and the El Paso Water Utility have dramatically lowered their unaccounted-for water with the help of a system of subterranean listening devices.
“Loggers” are small devices (measuring 2.4 inches by 5.3 inches), range in price from $350 to $700 (depending on the number purchased) and are positioned atop water main valves by means of a powerful magnet where they “listen” for specific frequencies between 0 and 3,000 Hertz. When a logger “hears” a noise with a consistent sound pattern and decibel intensity, the unit samples the noise three to 10 times at about 2 a.m. (when other distracting background noises are at a minimum). “If the logger determines that a leak is occurring, it radios out a response,” says Fluid Conservation Systems National Sales Director Lou Rossetti.
This response is in the form of a leak signal, which is usually picked up by a patrolling vehicle—similar to the way an automated meter reader works. However, there are modifications on the horizon that will allow loggers to send information to the monitoring utility via e-mail or text message.
Before permanent acoustic listening devices such as the Permalog (manufactured by Palmer Environmental in the United Kingdom and distributed in the United States by Fluid Conservation Systems) became available, utilities interested in improving supply side conservation would hire a consultant to do a manual survey. The consultant and crew will literally walk through the entire system listening to every valve and hydrant. If they were really on the ball, they would listen to every meter and service line in the system as well. After covering the entire system, the consultant would write up a list of leaks, pinpoint those leaks, mark the street above them, and turn in a report documenting his findings to the city, and then the city would go out and repairs those leaks. This process could take years (if not decades) to complete.
“Permalog changed everything for the leak detection industry,” says Water Conservation Service Co. President (formerly FCS Director of Special Projects) Danny Heredia. “Before Permalog, if a water utility decided to be proactive—and the majority of water utilities out there don’t do anything proactive in terms of leak detection—they’d go out with some acoustic listening equipment and do a manual survey, and then buy a correlator and pinpoint their leaks.
“What Permalog did was make it a whole lot more difficult for a water utility to come up with the excuse not to be proactive. Manpower was always the issue. ‘We don’t have guys to go out there and walk through this thing and monitor it on a daily basis.’ Permalog was the answer for that because you no longer have to worry about that—Permalog will tell you if you have a leak—and then you just have to go out and fix it.”
According to Heredia, whose company does all the patrolling, monitoring, and pinpointing of leaks for the El Paso Water Utility, the water utility industry in the United States is in a state of denial about unaccounted-for and non-revenue water.
“It’s just such a foreign idea to so many people,” Heredia says. I’ve dealt with directors of water utilities that had no idea of how much water they were losing—no clue. And the majority of water utilities are in that situation. … There were utilities where we went and did a test right in their own backyard, found leaks, pinpointed them, fixed them—everything went as perfectly as it could possibly go—and they still found a reason not to do any leak detection. ‘We just can’t afford it,’ they all said. And my answer was always, ‘You can’t afford not to do it.’”
Another possible explanation for why so many utilities aren’t willing to commit to a year-round proactive leak detection system is that before they can pony up hundreds of thousands of dollars to implement such a system, they have to admit that there’s a problem in the first place. And that can create quite the political hot potato because, even using the AWWA’s industry-accepted average of 3 gallons to 5 gallons per minute per mile of pipe, who wants to go before a public utilities commission and get grilled for admitting they don’t know exactly how big the problem is before it actually surfaces?
“The people in charge of the utility always thought about the political downside of having to explain that there are leaks they don’t know about, which are running unchecked right now,” says Heredia. “And they would rather keep that cat in the bag because once the cat is out, you have to explain it all.”
According to Heredia, early adopting cities like Las Vegas and El Paso were able to get behind a permanent leak detection system because they saw the political upside. Leaks happen. So why not take political (if not environmental) advantage of something that’s inevitable.
|Photo: Las Vegas Valley Water District|
|Permanent leak detection systems are essential benefits for desert metropolises.|
Viva Las Vegas
With the Colorado River at its lowest flow levels in recorded history and Lake Mead’s water level falling 70 feet since 2002, no one had to tell the Las Vegas Valley Water Utility that something had to be done to conserve more water. So in 2003, the utility purchased 8,000 Permalog loggers; today it has approximately 8,600.
Initially, the Permalog units were deployed on the utility’s 50,000 polyethylene service laterals, which coincidently were all attached to A/C mains. “Those were our two main areas of concern,” says Las Vegas Valley Water Department Distribution System Supervisor for the Vern Price. “The polyethylene is our principal concern. Now we’re starting to look at copper services that were installed to see if it’s worth it to go ahead and monitor that part of our system—whether or not we have enough leaks in that part of the system to justify monitoring.”
According to LVVWD Senior Maintenance Engineer Grant Laughter, “They’ve [polyethylene service lines] reached the end of their life. Their age runs between 17 years and 30 years. And our modeling indicates that the life of a polylateral in our system is between 25 and 28 years. The polylaterals are attacked by the chlorine in the water, the changes in temperature, and the water hammer [hydraulic surge].”
In 2004 (when the city officially went on a stage 2 drought alert), the LVVWD detected 253 underground leaks with the Permalog system, and using conservative methods (and an average leak rate of 2 gallons per minute), the utility estimates that it saved 200 acre-feet of water and $100,000 in power costs that year. In 2005, it saved an estimated 925 acre-feet of water, which brought its unaccounted for water percentage down between 2% and 4%.
Using conservative estimates, Laughter believes the Permalog program paid for itself sometime in 2005. “That’s partly due to that fact that in Las Vegas there are two main factors: l) We’re lifting water from below 1,200 feet to up into the range of 3,000 feet, so it requires quite a bit of energy; 2) The cost of new water rights is very expensive. We might buy the water rights somewhere else, but then we’d have to build the infrastructure to bring it here.”
With the cost of water rights in Las Vegas at about $4,500 per acre-foot, it’s easy to see why this kind of leak detection system would pay for itself quickly.
Las Vegas has its own logger-patrolling program, instead of hiring a contractor to do it. The city has even streamlined the process by using the same vehicles that do automated meter reading to record the Permalog alarms.
“We give them the same equipment as our Permalog controllers have,” says Price. “In my opinion, that’s an even better way to go about doing it because we’ve already got staff in the field doing their day-to-day activities and while they’re doing those, they can collect readings [Permalog] for you. And it’s not costing any more money to have them do it—other than the cost of an additional piece of equipment.”
Price is currently under-inspired by the technology involved with receiving a leak mode signal from a logger via e-mail or a text message. He sees it as an issue of cost and range. “You’re still talking about a radio frequency that’s down inside a hole in the ground trying to get out,” says Price. “When the loggers transmit, they would need to talk to a central unit [transmitter] mounted on a light pole in a neighborhood. Because of the transmit range of the loggers themselves, you can only have so many loggers assigned to each of these transmitters, so this kind of program would involve a lot of extra equipment. Several manufacturers are getting into the game, but it’s still all done using RF signals and subject to related reception issues.”
Putting the System in Place
As with patrolling its own system, the LVVWD made the decision early on to install its own Permalog system—a decision that carries with it the responsibility of fixing the problems it created.
“We used what ever extra manpower we could salvage up at the time,” says Price. “And you kind of get what you pay for with that—a few of the installs were not done with the quality they should have and had to be corrected. The install is one of the most important parts of the program. So you either let the company do the install for you, or make sure you assign trained people when doing it in-house.
“For example, loggers were not magnetically attached to the valve properly, which gives the impression that the units are on and ready to detect a leak, but in all actuality they don’t have the proper acoustic connection. You’re dropping in a bunch of loggers that will transmit every month but are never going to detect a leak,” Price says.
According to Laughter, “If you’re doing the installation in-house, you need a quality control/quality assurance program.”
Both Price and Laughter are satisfied now with their ongoing maintenance program where technicians go out and manually check each logger, vacuum the units out if need be, and do whatever is required to ensure that each unit is reading and recording accurately.
Having accurate leak detection is critical in a desert community that is home to more than a million people and blooms, in large part, because of expensive water that begins its journey hundreds of miles away. Even small leaks that go undetected for months can waste more water than diligent customers can make up for on the consumer side. To that end, Las Vegas patrols its loggers every six weeks—with the exception of outlying areas that are monitored about every two to three months.
“Nevada state law requires us to allow utility companies 48 working hours to mark their lines,” Price says. “We’ve partnered with our local utility companies to give our leaking work orders the highest priority, which allows us to repair the leaks quicker and conserve water. … Anything that’s leaking we’re going to fix within 48 hours—providing all utility line locations are available,” says Price.
According to Laughter, leaks are a priority—the goal is to fix them as soon as humanly possible. And two days is a proverbial drop in the bucket compared to the months or even years it took to detect or locate some leaks prior to implementing the Permalog system in 2003.
|Photo: Las Vegas Valley Water District|
|Las Vegas checks its loggers every six weeks to every four months.|
The One That (Almost) Got Away
According to Phil Bright, the non-revenue water manager for the American Water Company’s Southeast Region, you have to find and fix a lot of small leaks before you find the really big ones. “It’s because the loggers are picking up all sounds, and they really can’t tell if it’s a big leak or small,” says Bright. “A small leak may make more noise than a large one just because of the pitch. So you’ll have to check a lot of sounds before you find the ones that are leaking the most. Eventually you’ll get them, but it’s a matter of going out and fixing them as you find them … especially with the kind of soils in most of our areas where water doesn’t necessarily come to the surface.”
Bright’s advice holds just as true in Nevada as it does in Kentucky. As Price recounts this story about a main leak that went undetected for a year, the benefits of having a logger leak detection system goes beyond the realm of obvious into the land of “how did we ever get along without one?”
“We just thought it was a mechanical noise coming from the property. We couldn’t make contact with the property owner, and a drum of a swamp cooler rolling will generate a lot of noise. Even with ground mikes, that sound will go right into the plumbing and then into the ground and you can definitely hear it. This particular noise was so unusually loud that it almost sounded mechanical. And since we did excavate it once initially and found a dry hole, we just left the logger in place and ruled it out as a mechanical noise.
“At that point, we weren’t patrolling every six weeks. Initially, we were patrolling every two to three months in town. And after going to this site three times that year, I had another crew go out because we thought it was worthwhile to re-excavate one more time—just to be sure. We were just going to replace the copper service, even though we didn’t find water the first time—just to rule it out.
“They excavated it again, and again found a dry hole. We actually shut the service off at the main and sounded it again, and the noise continued unchanged. At this point, we actually made contact with the property owner and there wasn’t anything onsite that could be creating that kind of mechanical noise.
“So then we decided to chase the main either way a little bit, and they just shoveled a foot or so in one direction and they hit a big pocket of water, which exposed an 8-inch A/C collar, and the gasket on the collar was leaking. And there was a good spray of water too. So we know that that leak ran for at least a year with no signs or evidence—no water on the surface, no depression in the road. Who knows how long that would have gone undetected without the Permalog program?
“There was a gas line parallel to our main that was a few feet off. Between our trench and the gas trench, all that water was running down the trench line and channeling off somewhere else.”
The Case of the Missing Loggers
Because these kinds of sound monitoring devices, which look like a cross between a walkie-talkie and some sort of radio, are foreign objects to most people, extra care has to be taken by the utility to ensure that its investment doesn’t end up walking off the job—or worse as illustrated in this humorous anecdote told by Price.
“Recently, one of our crews spotted a local pipeline contractor’s vehicle driving down the street with two or three loggers stuck by the magnets to the hood of his truck.
“Our guys swung back around and flagged them down, and as it turns out, it was a couple of laborers who say they found them in valve boxes while they were working on a project, and they didn’t know what they were. So they probably would have taken them home or thrown them away.
“So we got to thinking. What if one of these loggers ended up in public place or at a school? They could be misidentified as a potential bomb or something—who knows. So we thought we’d put a sticker of our own on the loggers identifying them as our property and we developed flyers that we distributed to all our contractors and our metropolitan police and fire departments identifying what these units are and a contact number so they can call if one of them is found somewhere.”
Down in the West Texas Town of El Paso
El Paso is no longer a sleepy little border community on the Rio Grande famous for Tony Lama boots. In the last decade, it has become a fast-growing city of approximately 250 square miles, which along with its sister city, Ciudad Juarez, forms one of the world’s largest international metroplexes.
Even with twice the rain that Las Vegas receives, El Paso’s challenges to provide water in the coming years for its burgeoning population are substantial.
According to the El Paso Water Utility (EPWU) Engineering Associate Luis Castillo, “During the summer, we try to use as much surface water as possible coming from the Rio Grande, but we still use the wells [the Hueco and Mesilla aquifers on either side of the Franklin Mountains]. So it’s a combination. In the summer [March to October], we use both groundwater and surface water. In the winter, we rely on groundwater production.”
Castillo acknowledges the Hueco aquifer is being depleted, which is one of the reasons the utility has been looking at alternative sources of water and water conservation.
“El Paso tested the loggers for a while on a small scale—I think it was 50 or 70 loggers—and we found the leaks, so they knew it worked,” says Heredia. “We put them in place, left them there for a month or so, found some leaks, pinpointed them, got those leaks fixed, left the loggers in place in the same area, and found a couple more leaks. Once we got that area leak free, we moved them two or three times after the initial setup to give them a representative sample of the city.”
The initial Permalog trial was successful enough for the EPWU to purchase 10,000 loggers in two years. Between April and July 2004, the EPWU implemented the first phase of its Permalog leak detector system by installing 5,000 devices. The second phase, also 5,000 detectors, was between March and September 2005. The results are just short of staggering.
The utility estimates that the Permalog system saves 1.7 million gallons of water per day (approximately 5.3 acre-feet per day). Obviously, that kind of supply side savings goes a long way toward providing water for a rapidly expanding population. When you consider a family of four in El Paso uses approximately 600 gallons of water a day, it’s easy to see the need for this type of conservation.
When the program began in 2004, repairing three leaks saved an estimated 220 gallons per minute. In 2005, the utility added the second phase and reduced the sum of all leaks to 178 gallons per minute. By 2006, the 21 leaks repaired reduced the amount of water lost to 50 gallons per minute—a 77% change when just comparing the three leaks repaired in the peak season in 2004.
As with Las Vegas, El Paso uses the Permalog system on a permanent basis (instead of attempting to cover the same ground with fewer devices and rotating them to different locations throughout the network).
Unlike Las Vegas, the EPWU contracts with the Water Conservation Service Co. to patrol for leaks and pinpoint them when it finds a leak alarm. “We’ve got the system down to where it’s totally smooth and seamless,” says Heredia. “Our guys go out there everyday doing patrols, find the loggers that are in leak mode, and turn in a report to the guys who do the pinpointing, who go out and investigate. Some days we find a couple of fire hydrants. … Just the other day, they found two main-line leaks. So it’s an ongoing process. Once we pinpoint it and put a blue ‘X’ on the street, we generate a daily report, which gets e-mailed to the EPWU. In turn, they generate a work order and go out and fix it.”
Heredia contends that it’s easier and more cost-effective for a utility to hire a contractor to deal with hiring and training personnel plus the costs of vehicles, equipment, and doing the actual work. “We can do it more efficiently when it comes to the financial side than most utilities.”
According to Castillo, the only interesting story concerning the Permalog system was discovering an unmarked water main: “On one occasion, they reported a leak on a water main, and we went ahead and exposed the pipe to fix the leak. What we found was a valve that was almost closed. We didn’t even know that this valve existed. And even though we didn’t find a leak, we found a partially closed valve, which was making the noise. So we opened the valve.”
But Castillo is quick to point out that the beauty of the Permalog system is its ability to discover and locate leaks that are not detectable on the surface. “On many occasions, the water goes underground, and nobody knows about it. That’s one nice thing about this program.”
As the West continues to warm and weather patterns become less predictable, the lessons learned by these two desert utilities will undoubtedly prove usefulto managers, engineers, and planners in areas not currently experiencing this level of aridity. Another way of looking at the value of a leak detection system like Las Vegas and El Paso have is that it’s tough to say no to a program that pays for itself in two years and saves upwards of 1.7 million gallons of water a day.
Author’s Bio: Guest author Mark Saunders is a newspaper and magazine journalist based in Boulder, CO.