Looking for leaks before they reach the surface

Listening underground to cut down on expensive main breaks, identify weak pipes, reduce costs and curtail water waste.

January 23, 2014 | By: Ann Baker
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Jim Aragon measures the distance between two correlator outstations, which is equipment that helps detect a leaky pipe.

One of the hardest things about finding a leak is listening for it.

Was that hollow swooshing the sound of a sprinkler running? A washing machine filling? Or the sound of a leak that’s causing lost revenue, water waste and potential damage to surrounding infrastructure?

Each year, a four-member crew surveys roughly 500 miles of pipe, searching for sneaky leaks that have yet to gurgle up from the ground.

“A pipe could leak for years and you’d never know it,” said Jim Aragon, one of the crew members with the leak detection program. “It would just go right into the Platte River, following the storm sewer or another conduit. Leaks find the path of least resistance.”

One of the goals of Denver Water’s leak detection program is to survey the entire distribution system – which has almost 3,000 miles of pipe – and pinpoint the leaks to help our operations and maintenance crews repair the problem spots.

Finding those non-surfacing leaks cuts down on expensive main breaks, identifies weak pipes, reduces excavation costs and curtails water waste. Over the past five years, Denver Water leak detection employees surveyed more than 3,800 miles of pipe and pinpointed more than 500 underground leaks. They also worked with our operations repair crews to locate nearly 600 surfacing leaks.

Fixing all those leaks saved an estimated 138 million gallons of water — water that would have been unaccounted for.

“It’s really important,” Aragon said. “We’re saving hundreds of thousands of gallons every year.”

To find the leaks, crews place data loggers on top of a pipe on a street corner’s valve box.

The data loggers capture three days’ worth of information about the pipe, documenting any unusually steady sound frequencies that might signal a leaky pipe.

pull-quote.cropOnce the data loggers show that a leak is in the area, crews place correlating equipment with magnetic transducers on pipes or valves to send frequencies to a computer. The computer then helps the crew narrow down the leak’s location on the pipe.

As soon as the readings say they’re close, they’ll drill through the asphalt, stick a metal rod into the hole so it touches the pipe, and use headphones to listen for the hollow swooshing sound of a leak, usually marking the spot within 3 feet of the actual leak.

“The big thing is being able to tune your ear to the sound of a leak,” said Rodney Edwards, a water quality investigator who worked in leak detection for four years. “You’ll hear cars passing, laundry machines running. You have to really key into what a leak sounds like.”

Finding leaks is like solving a big audible puzzle. The hollow leak sound may be a sprinkler system running or a hose gushing with water. Sometimes, when they’re searching for leaks in busy urban areas, the crew will have to return late at night so they can concentrate on the sound of the leak without the interruption of car horns and diesel engines.

“The equipment will help indicate that there’s a leak in the area,” said Joe Duran, distribution operations supervisor. “But they have to investigate, correlate and analyze data to actually detect the problem.”

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Mike Sanchez listens for a leak.

A few years ago, maintenance workers at the zoo couldn’t figure out why the lemur pond and the duck pond kept filling up with water. Aragon and fellow crew member, Mike Sanchez, headed there after-hours to avoid the noisy crowds.

“We went out there at night and the animals were going crazy,” Aragon said. “We were listening for the leak and heard bears growling from the other side of the zoo.”

They found two problem valves that were allowing water to flow into the ponds, even after the zoo’s maintenance staff had attempted to shut them off.

Most of the time, the pipe’s age is to blame for the hidden leaks. Sometimes, other utility crews may have nicked a pipe while repairing something else underground, causing a gradual and destructive problem.

“Customers find it very interesting that we’re out there looking for leaks and trying to conserve,” Edwards said. “They say, ‘you’re doing what? How cool.’”

0 thoughts on “Looking for leaks before they reach the surface”

  1. It’s great what the team does! Is there a way for them to loan themselves to older HOA neighborhoods (which have their own network of pipes coming from Denver Water’s boxes) to detect potential leaks? Some HOAs can’t afford technology or service like that so they could help conserve water.

    1. In some cases we are able to work with entities on leak detection for conservation purposes. But each situation is unique, so it would be best for you to call and discuss your request with Denver Water’s community relations specialist, Joe Sloan at 303-628-6320.

  2. We are desperate. The water auditors found no leaks, but still blame our sprinkler system for astronomical water use and catastrophic bill for July, now again for August. We would have to be watering our lawn 24/7 or leaking the size of an Olympic swimming pool. No sink holes, no flooded basement, no evidence of anything out of the ordinary. What should we do? Please help. They are going to shut off our water if we can’t pay. We are senior citizens.

    1. We have the same problem. The water auditors found no leaks. We have no sprinkler system and a slab foundation. They claim we are wasting 29,000 gallons a month!! Really?! No leak anywhere. No water anywhere. No sink holes. No basement. No evidence of anything out of the ordinary. Anyone, please help us. We don’t know what to do. And we can’t pay this massive bill.

      1. Several years ago, our HOA was leaking around 40,000 gallons. We took a couple of drastic moves:
        1. Pulled all the sewage manhole covers and looked down them with a flashlight. Normally, there’s only a trickle of sewage water (sometimes more if someone’s washing their clothes). However, if you see a large, steady stream of mostly-clear water rolling through, it’s likely you have an underground water leak that’s flowing directly into the sewer lines. (That was our problem… the loose water never went into a basement nor appeared on the ground-surface level).
        To correct this, we had to get a true professional – Dave Anderson of Utility Technical Services. He has professional, high-level computer equipment to pinpoint leaks. Do NOT waste money on some of these other plumber-types who claim they can find leaks. Dave found our leak within an hour (in fact, five of them within a few dozen yards of each other). We got a construction crew to come and fix them – problem resolved.
        2. Consider switching traditional sprinkler heads to MP-Rotary ones. they use water more efficiently and use less water in doing so. (Denver Water offer rebates for many sprinkler heads like these.)
        How much has some of this work cost our HOA, Cherry Creek 3? Several thousand dollars BUT a pittance compared to how much we’ve saved, both in terms of water and outgoing sewage costs.
        This fiscal year, our 251-home HOA will consume around 21 million gallons of water, roughly 15 million fewer gallons than the 36 million we used back in our 2008-09 fiscal year.

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