Archive for January, 2014

Looking for leaks before they reach the surface

By Ann Baker, Denver Water Communications and Marketing

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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 nonsurfacing 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.’”

Another 100 years for Antero Dam

Antero Reservoir was built more than a century ago by Antero & Lost Park Reservoir Company.  Denver Water bought the reservoir in 1925.

Antero Reservoir was built more than a century ago by Antero & Lost Park Reservoir Company. Denver Water bought the reservoir in 1925.

By Ann Baker, Denver Water Communications and Marketing

Denver Water recently started a two-year, $14 million dam safety project at the 104-year-old Antero Dam to bring it up to current engineering standards.

The dam’s name is derived from the Spanish word “first,” as Antero was the first dam on the South Platte River near the river’s origin. It’s located approximately 100 miles southwest of Denver near the small town of Hartsel. In 1925, Denver Water bought the earthen dam, built at the site of a former lakebed, from the Antero & Lost Park Reservoir Company.

The dam, three-quarters of a mile long and 46 feet tall, was built on top of the ground, instead of on top of the stable bedrock well below the surface. As a result, water has seeped through over the years, causing internal erosion that, if not fixed, could cause a full breech of the dam, said Jeff Martin, design project manager. In 1985, this issue prompted the Office of the State Engineer to restrict Antero’s storage to 20,000 acre-feet — about 6,500 acre-feet less than the spillway would allow.

Crews build a sand trench on the downstream side of Antero Dam to filter the normal seepage of the dam and to stabilize the foundation.

Crews build a sand trench on the downstream side of Antero Dam to filter the normal seepage of the dam and to stabilize the foundation.

Throughout Colorado, 155 dams are restricted for safety reasons, accounting for 62,000 acre-feet in restricted storage. Antero is the fourth largest on that list, with about 10 percent of that restricted storage, said Bill McCormick, chief of the dam safety branch of the Office of the State Engineer.

“Denver Water should be recognized for doing this,” he said. “This is a big project that will make a difference in the amount of storage that’s restricted across the state.”

The project

In August, crews began the first phase of the dam safety project by building a sand trench to filter the normal seepage of the dam and to stabilize the foundation. Crews have to work around the nasty winters at Antero, where frigid temperatures can prevent diesel engines from starting, wind blasts can cause a person to stumble, and frost 5 feet deep can make it nearly impossible to dig.

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Crews will start the second phase next spring, during which they’ll grade the embankments. They plan to finish in 2015 with a new barrier wall and spillway.

Once repairs are complete, the dam will be about 4 feet lower, with a gentler slope on both the upstream and downstream sides.

“This steep of a slope has erosion problems — it’s just not current practice,” said Doug Raitt, construction project manager.

The dam’s new barrier wall will prevent water seepage, while the new sand filter will protect against internal erosion and the resulting dam safety issues. Currently, the water level is restricted to a depth of 18 feet, but for the past few years, Denver Water has kept it at 16-17 feet for safety reasons. After the improvements, the reservoir could safely store a water level of 26 feet; however, a water level of 18 feet is sufficient to support Denver Water’s collection system at this time and will be maintained for the foreseeable future.

This is one of the largest upgrade projects ever at Antero. In the early 1980s, Denver Water reconstructed the spillway, and in the late 1990s, crews built a new outlet works to increase the hydraulic capacity.

Completing this project “will make this whole dam more stable,” Raitt said. “It’ll make sure this dam lasts another 100 years.”

Groundbreaking agreement to benefit Colorado and the environment is official

A groundbreaking agreement is now effective, ushering in a new era of cooperation between Denver Water and West Slope water providers, local governments and several ski areas.

The Colorado River Cooperative Agreement was fully approved Sept. 26, 2013, with signatures from all 18 partners complete. The overall goal of the agreement is to protect watersheds in the Colorado River Basin while allowing Denver Water to develop future water supplies.

The agreement is the result of more than five years of negotiations and creates a spirit of cooperation – instead of litigation – over water resources.

From L to R: Penfield Tate III, Denver Board of Water Commissioners; Grand County Commissioner James Newberry; and Gov. John Hickenlooper share a light moment during the CRCA signing between Grand and Summit counties, Denver Water and the Clinton Ditch & Reservoir Co. in May 2012.

From L to R: Penfield Tate III, Denver Board of Water Commissioners, Grand County Commissioner James Newberry, Summit County Commissioner Dan Gibbs, Gov. John Hickenlooper and Summit County Manager Gary Martinez share a light moment during the CRCA signing between Grand and Summit counties, Denver Water and the Clinton Ditch & Reservoir Co. in May 2012.

Some of the benefits include:

  • Additional water for towns, districts and ski areas in Grand and Summit counties to serve the needs of their residents and to improve the health of our rivers and streams.

 

  • Provides protections for river flows and water quality along the entire reach of the main stem of the Colorado River.

 

  • Enhanced recreational opportunities by providing additional water to certain ski areas.

 

  • Establishes a broad-based management team – dubbed the “Learning by Doing” process – where representatives from Denver Water, Grand County, the Colorado River District, the Middle Park Water Conservancy District, Trout Unlimited, Colorado Parks and Wildlife, and others will use water and funding provided by Denver Water and others, and the flexibility in Denver Water’s system to manage flows for the benefit of the environment in Grand County.

 

  • Reinforces the priority and increases the amount of conservation and reuse within Denver Water’s service area.

 

  • West Slope parties agree not to oppose any permits for the Moffat Project, Denver Water’s plan to enlarge Gross Reservoir.

Never in the history of Colorado have so many varied interests agreed on a shared vision for a secure and sustainable water future. This approach will provide proper balance among competing interests, a shared vision for better river health, reliable supply for all water users, and a future of cooperation, not conflict.

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