WATER: Clamping Down on Losses

Leak detection initiatives in Iowa City help the Water Division minimize non-revenue water and scale down a new treatment plant.

A 100-year decision changed the course of the Water Division in Iowa City, Iowa.

The original water treatment plant, built in 1882 and upgraded twice, was nearing the end of its life. In 1990, the city began researching a new water purification facility.

Based on population projections, gallons per capita expectations, and growth, the plant’s projected capacity and size kept increasing, as did the cost. The city council charged the utility to look at the effect of proposed rate increases and the potential to reduce non-revenue water, believing it would be possible to downsize the plant through leak prevention and conservation.

Ed Moreno, division superintendent, and staff, picked up the gauntlet. Leak detection became their battle cry, backed by an innovative water conservation education program. Minimizing accountable and non-accountable water losses enabled the city to optimize its investment, while providing consumers with a high quality product.

The results speak for themselves. In 1992, the Water Division provided 6.7 million gpd to 18,400 accounts. In 2007, it had 24,000 customers, yet they used only 5.6 million gpd. The new plant’s water capacity of 16.7 million gpd is enough to meet Iowa City’s growing needs far into the 21st century.

Vintage years

Iowa City is home to the University of Iowa. More than 85 percent of the Water Division’s 24,000 accounts are residential, encompassing the city proper and a town inside the city called University Heights. The university has its own water treatment plant, distribution system, and wastewater collection system. The utility’s 25-square-mile service area has 2- to 30-inch cast iron, ductile iron, and PVC water mains.

Early cast-iron pipes had thick walls. “They remain very hearty,” says Moreno. “Cast-iron pipes made during World War II and into the 1950s, when materials were scarce, are troublemakers.” Iowa City migrated to ductile pipe in the early 1970s.

Leaks aren’t due just to inferior metal. The area has pockets of corrosive soils that attack the brittle, unwrapped pipes. Freezing and thawing buckle the ground, creating circumferential breaks.

“Before 1998, we knew we had a leak when water surfaced,” says Moreno. “We’d bring in a leak detection group only if we couldn’t find the source. Things were going on in those pipes that we knew nothing about. The council’s charge changed everything.”

Moreno first consulted with larger communities that had their own leak detection equipment. He also called the sales representative of the leak detection equipment used by the city’s contractor. “The salesman couldn’t make it work,” says Moreno. “It became apparent that if you didn’t use the equipment every day to keep up your skills, proficiency suffered.”

In 1998, Iowa City signed a three-year contract with Westrum Leak Detection of Stratford, Iowa, and has negotiated extensions ever since. Westrum inspected the entire service area. The Water Division then fixed the leaks identified in the city.

After that, the city, except downtown, was divided into three areas and put on a three-year rotation. “Our program, which is now preventive maintenance, focuses on one area plus downtown every year,” says Moreno. “Westrum finds the smaller leaks that are all over and sends an annual report.”

Earning their keep

The report identifies leaks in mains, abandoned lines, service lines, hydrants, and valves. Initially, leaks averaged 9 million gallons a year, while the leak detection service cost the city $7,000. “The justification for this program was apparent in the beginning,” says Moreno. “Our average payback period was a little more than seven months. Recouping all the leaks really added up.”

Water mains were mapped as they were surveyed, digitized, and entered in the utility’s AutoCad program. “We’re working on databases for asset management,” says Moreno. “Our next goal is to step more firmly into geographic information systems (GIS). We’ve done a pilot project, but haven’t gone full-fledged into GIS yet.”

Westrum surveys the mains in late August, using fast spectral correlation to locate leaks. Sound waves, transmitted from two opposite points in the pipe, spike on the computer monitor when anomalies are present. The operator then evaluates what is causing the spikes and identifies their locations.

“When we dig, we find the leaks exactly where Westrum says they are,” says Moreno. “The company has nearly a 100 percent accuracy rating with us.”

Once a leak — usually a circumferential break — is located, Water Division crews excavate using open cut or trenchless technology, clean the pipe, and put a stainless steel band around the break to repair it. If an undetected leak presents itself as water bubbling up and excavation doesn’t reveal the source, the men pothole using an HXX Prodigy hydroexcavator from Vactor Manufacturing.

Directional boring

The utility is moving toward more directional boring, too. “At first, we directional bored in areas with only a few service lines, but now the majority of our projects use it so we don’t dig up entire neighborhoods,” says Moreno. “The technology enables us to accomplish more and to serve our customers better.”

Moreno is proud of the pipe replacement work accomplished in the last 10 years, and of the budget allotted for it. In 2007, the city spent more than $800,000 on replacement, a considerable amount for a small utility.

The city has contracted Central Iowa Water Association in Newton and, more recently, Gaylord Construction Inc. in Fort Madison, Iowa, to do its directional boring. Water Division crews prepare the sites. “We use Certa-Lok C900/RJ, a restrained joint PVC pipe from CertainTeed Corp., and can replace several hundred feet a day,” says Moreno. Gaylord uses the Ditch Witch JT2720 drilling rig.

After the pipe is pulled, it is pressure and bacterial tested. Then Moreno’s team connects the service lines and does the restoration work. “We replace the main to the stop box with copper pipe,” says Moreno. “When necessary, we use our pneumatic percussion boring tool from Pow-R Mole to cross beneath streets.”

Catastrophic failure

In 2007, the utility began a valve exercising program, and Moreno anticipates inspecting all valves within five years. However, the need for such a program was emphasized 20 years ago during the division’s most challenging repair.

Crews were trying to locate a 20-inch water main beneath a brick street alongside the old plant. During the exploration, the backhoe hit the pipe (stamped with the date 1890), releasing high-pressure water that shot bricks skyward and eroded a massive hole on its journey to the Iowa River.

“The plant went down immediately, activating the pump stations,” says Moreno. Iowa City is unique in that its 6 million gallons of emergency water are stored below ground in pre-stressed concrete tanks with pump stations.

Unable to isolate the main because the valving was inoperable, Moreno watched stored water levels drop slowly until they were no longer maintainable. “This was in winter, so demand was lower,” he says. “We opened some interconnections with the university’s water plant and maintained low-pressure service throughout the city. However, we issued a boil order as a precaution.”

The main was eventually isolated. Finding ductile iron pipe to fit the oversized damaged section took 30 some hours. The utility installed many new valves in later projects to isolate the line. “The emergency showed the importance of having a valve exercising program,” says Moreno. “Those things have to work.” From 1998 to 2007, Westrum found only two leaking valves.

Tracking losses

Besides monthly meter readings, the Water Division assists homeowners in monitoring leaks through its billing system, which punches out abnormal usages. “If normal usage goes up or down by half, we verify it, then leave a notice suggesting that homeowners look for leaking toilets, faucets, or open outside spigots,” says Moreno. If they can’t find the leak, customer service is dispatched to help.

A university town has numerous apartments. Iowa City meters most of them individually. “It’s another tool we use to identify leaks,” says Moreno.

Accurate water usage depends on accurate meters. The old plant had insertion prop meters that were calibrated every two years. “They still weren’t as accurate as the mag meters in the new plant,” says Moreno. “We feel pretty good about the accuracy of our metering now.”

In addition, the utility has a meter change-out program tied with a water meter radio-read system to expedite billing. “When we started in 2001, some of our meters were 30 years old or older,” says Moreno. “They were losing efficiency in all three ranges. As they were replaced, we gained a more accurate picture of our non-revenue water.”

While many factors enabled the utility to reduce its per capita usage, Moreno believes raising water rates was a key component. “That forced customers to really look at their usage,” he says. “Once the rate structure began increasing, the City Council requested that we offer citizens a conservation program, which was heavily promoted.”

The new plant’s purification process helps residents conserve water, too. Seventy percent own water softeners, but the water they receive now has only 7 grains of hardness instead of 20-plus grains. “That caused a significant change in water usage because people no longer dumped 50 gallons every time the softener recycled,” says Moreno.

Thanks to Moreno and his staff, and the cooperation of city residents, Iowa City is on course for an ample supply of high-quality water for many years to come.


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