The water system in the City of Decatur serves a population of 79,000, but even more noteworthy is its thirsty base of industrial customers. So when the city first considered a comprehensive study of water loss a few years ago, it seemed like a pretty good idea.

 

“We’re always looking at our water accountability,” says Randy Miller, water services manager. “You’re always upgrading your meters to make sure they’re accurate. This was just one piece of the puzzle: Let’s find some leaks that we can’t see.”

 

In summer of 2010, Decatur completed its first three-year comprehensive leak detection program. Total savings? Five times what the program cost. It should come as no surprise that they’re planning to repeat the project.

 

Industrial city

Decatur, in central Illinois about 180 miles southwest of Chicago, is a heavily industrialized city. Its water system is fed by Lake Decatur, a reservoir built on the Sangamon River in the early 1920s. The system serves the city and the neighboring village of Mount Zion. Total system capacity is 36 mgd, and the average usage is 20 mgd.

 

“About three-fourths of the water we produce at our water treatment facility goes to commercial and industrial customers,” says Keith Alexander, director of water management. “Some of the largest agriculture grain processors in the world are located here.” Heavy manufacturers also have a significant presence.

 

“We have a good revenue stream from very large customers,” Alexander says. “But it also means we need a very robust system. We have a large need for raw water supplies. We have built a very large water distribution system, including water mains, valving and elevated storage facilities — all oversized for a community of our size and population.”

 

That kind of infrastructure costs a lot to maintain. “That’s why, any way we can reduce the cost to our customers, reduce the amount of water we have to purify, and conserve our raw water supply, we will,” Alexander says.

 

Where the water goes

The need became clear a few years ago. “We had about a 17 percent apparent water loss between what we pump out of our water treatment plant and what we bill to our customers,” says Alexander. “We thought one of the most important ways to start toward lowering that percentage was to do a systemwide leak detection survey.”

 

Decatur issued a request for proposals and qualifications for a survey of its more than 500 miles of mains to a set of prequalified regional firms. After face-to-face interviews with the two top candidates, both highly qualified and well known in the industry, the city hired ADS Environmental Services.

 

ADS and the city agreed to a three-year program that divided the community into three parts. The first phase took place in 2008 and the last one was completed in July 2010. For each year’s phase, ADS technician Terry Keeling spent four to six weeks methodically going over every main in search of leaks.

 

The first year’s phase focused on the part of town with the oldest water mains. The city had already identified some sites where leaks were suspected.

 

Large and small

For each suspected leak, the technician produced work orders with a street address and an estimate for water loss. “The majority of the leaks were hydrants that were probably not shut down properly, or they were seeping water,” Miller says. “The technician would repair them on site, just adjusting the hydrant.”

 

The extent of leakage from hydrants surprised city officials. “Certainly we had the majority of our water loss through our water mains,” says Alexander. “But the amount that we were losing from hydrant leaks and water service leaks surprised me. I didn’t expect those numbers to be as high as they were. Those are easy fixes that we were able to do right away.”

Individually those leaks weren’t very large — typically on the order of a thousand gallons or so a day. “Then there were service leaks that had a little bit more volume,” Miller says. “We had one that was more than 600,000 gallons per day.”

 

The accuracy of the locating effort impressed city officials, but the project was unknown territory for Miller and Mark O’Connor, the city’s water distribution maintenance supervisor.

“Our biggest concern was that we wouldn’t be able to keep up with the digs — that we were going to be running helter-skelter trying to get this done,” Miller says. “That really wasn’t the case. We were pleasantly surprised that we didn’t have as many digs as we thought we might.”

 

By breaking the project into three phases, the city limited the scope of the work enough so that the staff could keep up with the repairs. “In 2008 we were probably done about a month after the ADS technician was gone,” Miller says.

 

That was important because as winter moved in, the department knew that seasonal water main breaks would spike from October to February, keeping crews too busy to take on any additional work that might result from the leak detection project.

 

Big payoff

Miller’s worst fears of the project didn’t materialize. “I was afraid we were going to find a lot of big leaks,” he says. “That wasn’t the case. We did find a lot of small leaks that added up.” Altogether, the project cost the city $80,323. Crunching the numbers from the 2010 phase of the survey, Alexander says, “We figured that for every dollar that we spent, we saved $5.30 in water that we did not have to produce, so the pay-back is tremendous.”

 

Alexander isn’t sure yet exactly how much the city has reduced its water loss from the original 17 percent. An ideal goal would be to reduce the water loss to about 10 percent, but that’s likely to take time, “especially for a community that has an aging water distribution structure such as ours,” Alexander says.

 

Beyond that dollars-and-cents payoff, the project offered a wealth of knowledge. “It kind of gave us a real good snapshot of our system,” says Miller. “It just makes you feel better that you don’t have any great big leaks out there.”

 

“We did find enough leaks that it gave us a bit of an education about how we can reduce leaks, especially in the way of hydrant usage.” City crews also learned about leak detection and how to listen on their own for leaks.

 

When the city draws up its new budget in early 2011, the water utility plans to ask for money for another leak detection survey. That will probably once again be on a three-year cycle, although there are other options, such as dividing the system into just two sections, or even doing it all in one season.

 

Alexander says the savings was so substantial that it will be an easy sell. “I would strongly encourage any water utility that has not done a leak detection survey in recent memory to seriously consider doing so,” he says.