The City of Kingsport, Tenn., estimated it was losing more than 1.2 million gallons of water, and associated revenue, to leaking pipes each year.

 

As a remedy, the city undertook a performance contract that saw the installation of new water meters with automated reading and a sophisticated leak detection system, together guaranteed to save the city more than $15 million over 17 years.

 

The deal had its genesis at a 2008 meeting of the Tennessee City Management Association, where Miles Mennell, business development manager with the Building Efficiency business of Johnson Controls, presented a seminar on performance contracting as a procurement strategy. In the audience were Kingsport city manager John Campbell and public works director Ryan McReynolds.

 

“I had known John for some time, and after the meeting, I approached him with a business proposition,” says Mennell. “I offered to make a presentation to the city in which we would enhance the billables in the water system to self-fund infrastructure improvements.

 

“No other city in the state had used performance contracting to upgrade its water utility with automated meter reading and a leak detection system. But John is a true visionary, so he’s very receptive to nontraditional ways of getting things done.”

 

Sophisticated leak detection

The city was mainly interested in automated meter reading, but Mennell suggested a sophisticated leak detection system that would automatically detect system water losses, enabling the city to make repairs. The meter reading system allows city workers to read meters from their vehicles, increasing billing accuracy and improving customer service. The projects would allow Kingsport to make significant infrastructure improvements without touching reserve funds, raising fees or taxes, or issuing bonds.

 

“The largest portion of the city’s water system was built in the 1920s, with a resurgence in infrastructure construction during World War II,” says McReynolds. “It’s seen a lot of service.” The water system was aging and beginning to leak, but the area’s soil is porous, so leaking water often percolates through the soil without surfacing. The accuracy of the city’s water meters was also called into question.

 

“We have an abundant water supply with low turbidity, but our problem wasn’t with the supply,” says McReynolds. “We were losing billable water into the soil, and although the meters weren’t worn down, we realized they could more accurately reflect the sale of water to each customer. By improving those two things we realized we could become better stewards of our water resources.”

 

Under the performance contract, Johnson Controls financed the up-front cost of the improvements, and the city is paying the money back out of the cost savings and increased revenue those improvements generate. In the event the savings fall short of the amount guaranteed by contract, Johnson Controls would be required to write the city a check to cover the difference.

 

Best for the job

As a first step, Johnson Controls representatives tested the existing metering system and estimated its accuracy at 94 to 96 percent. “The company felt comfortable that by installing new meters, the accuracy of the system would range between 98 to 100 percent, increasing revenues and allocating costs accurately to the customers who use the water,” says McReynolds.

 

The city had its choice of meters and selected Master Meter Bottom Load Multi-Jet (BLMJ), with integrated encoder, RF transmitter, battery, and antenna placed inside a stainless steel and tempered glass shell. New meters were installed for more than 34,000 service connections, representing 80,000 customers.

 

“One of the benefits of the automated meter reading is that we removed various vehicles from running the routes,” says McReynolds. “We took five pickup trucks off the road and went as fuel efficient as we could go with one Toyota Prius that collects data by driving past the meters one day a week.”

 

The installations also included Itron MLOG leak detectors on the city side of the service connections. The units employ acoustic sensor technology and sound analysis software to help identify water loss across the entire water distribution system. The system analyzes changes in the level and frequency of water pipe sounds and uploads detailed reports on potential leaks to a database accessible to the city staff.

 

The MLOG does most of its work when the system is quiet, between midnight and 3 a.m.

 

Electronic reporting

Each morning, employees accessa report listing potential leaks in terms of likelihood, setting priorities for investigation by the water department and marking the locations on a computerized map. Color-coding identifies new potential leaks and those still carried on the books from previous reports. Work crews are then assigned to investigate the potential leaks, flagging some of them for imminent repair.

 

“A technician will go to these reported addresses and try to refine the location and pinpoint the leak,” says McReynolds. “Once the location is identified, the site is spray-painted and a construction crew follows in four to five days.”

 

The reports are accessible both to the city and to a Johnson Controls specialist who provides a monthly report to the water department. “It essentially says that these leaks look possible and these look probable,” says J.B. Carson, performance assurance specialist with Johnson Controls.

 

“The reports do an excellent job of prioritizing investigation and repair activity. The goal here is not to reach a day when there will be no probable leaks detected, but to reduce the number of likely leaks and see an improvement in the entire system. It’s like a dog chasing its own tail, but in smaller and smaller circles.”

 

Saving water and energy

As of late October, the system had identified some 50 line leaks and breaks, enabling the department to make repairs and prevent the loss of more than 1,685 gallons of treated water per minute. As Reynolds points out, that saves both water and the energy required to move and process it.

 

“The savings also don’t take into account the difference between responding to a potential leak proactively, and responding to an emergency leak in the winter, with road closures and crews working during the night,” says McReynolds. Most repairs in Kingsport are dig-and-replace. The typical depth of waterlines is about three feet, though some older mains are just 18 to 20 inches below the surface.

 

“For mains six inches and above, which are mostly cast iron, we replace with ductile iron,” says McReynolds. “For smaller lines, we consider PVC. In established neighborhoods, we sometimes go with directional drilling for smaller lines.” Some larger mains are diagnosed with faulty leaded joints, which are also repaired.

 

Identifying usage

In addition to detecting leaks on the city side, the MLOG device pinpoints customer water usage, and waste, by logging usage patterns in 15-minute increments.

 

“In one case, we had a dispute about the amount of water used by a customer, and we were able to show this gentleman that the volume of water in dispute was exactly the amount required to fill his swimming pool,” says McReynolds. “We showed him exactly when he started filling the pool and when he finished.”

 

The MLOG can also identify customer leaks with high accuracy, pinpointing problems such as faulty toilet valves.

 

The leak detection system has created a backlog of potential repairs that crews are tackling on a computer-prioritized schedule. “There’s more there than we can get to in a month, but the same soil conditions that make it difficult to detect some leaks by eye, also allow us a bit of leeway in dealing with them,” says McReynolds. “In many cases, the water just goes straight down into the limestone through voids and fissures.”

 

But crews are slowly gaining on the leaks. As part of the contract, Johnson Controls will test the accuracy of the system in about two years.

 

“We’re very happy with the way the performance contract is working for the city,” says McReynolds. “We’re containing costs, improving customer service, and demonstrating stewardship of our water resources in meaningful ways, while financing our own infrastructure improvement on system savings. As long as we maintain our end of the contract, the savings are guaranteed.”