Eliminating Loss

Award-winning water district targets leaking lines and inaccurate metering in bid for greater efficiency.
Eliminating Loss

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From the moment Public Water Supply District No. 1 of Ralls County, Mo., turned on the pumps in 1971, the new distribution system leaked.

About 30 percent of the district is hilly and rocky. Contractors installing the solvent-weld, thin-walled PVC pipes tossed them into trenches without bedding, then backfilled. "Rocks cracked or punctured some pipes the day they were laid," says Jon Rogers, local manager of Alliance Water Resources, a provider of management and contract operations services in Missouri and surrounding states.

The water district purchases 165 million gallons of water annually from the city, distributing an average of 450,000 gpd to 6,300 residents in eight communities and surrounding rural areas. Before 2006, the district lost 40 million gallons per year. Unable to find certified operators and qualified staff to address the problems, the board of directors hired Alliance in 2001.

From 2004 to present, Rogers and a staff of six reduced water loss from 27 percent to 10 percent through aggressive meter change-outs and leak detection programs that culminated in two major pipe replacement projects totaling $5.375 million. They ran accountability audits, improved system maintenance and safety, and computerized billing, collections and financial reporting. In 2012, the district earned the System of the Year Award from the Missouri Water and Wastewater Conference Northeast Section for its achievements.

Early efforts

The district, running 30 miles along the Mississippi River, has three pump stations, five elevated storage towers totaling 550,000 gallons, and 350 miles of distribution mains. Although the city sits on a vast alluvial plain, it draws surface water from the river.

Rogers' team spent the first three years evaluating the situation. They began by auditing 1,600 customer- or self-read meters to verify billing accuracy. "Most residents made honest errors, such as omitting the zeros in the meter's last digits," says Rogers. "Others estimated their water usage rather than read the meters."

Although those incidents contributed to expenses exceeding revenue, they weren't significant enough to account for the major discrepancy Rogers saw over the summer. Wondering what was going on, he asked his office manager and part-time assistant to look at accounts for appreciable seasonal variances.

"We located some 100 swimming pools filling at 30,000 gallons," he says. "The owners were spacing out payments over three or four months. Because the board wanted to keep the self-read meters at that time, we educated the owners and brought a billing system with better accountability." The remaining 1,100 meters were employee-read, a task requiring three days per month.

Metering progress

Having cleared the low hurdles, the team determined its first project. The district had a $500,000 transmission main that was never activated because it needed a pump station. In 2004, contractors built it, installed three 20 hp Gorman-Rupp pump skids, and put the main online to improve service. Customers noticed.

The team then evaluated water loss to control affiliated costs and came up with five areas requiring attention. Meter accuracy topped the list. Some 5/8- by 3/4-inch-diameter residential meters were more than 35 years old and registered more than four million gallons. "We estimated that 30 percent, or more than 800 meters, were below American Water Works Association standards for replacement," says Rogers.

As six field workers maintained the system, they began replacing a minimum of 250 of the worst meters a year with T-10 meters from Neptune Technology Group. "Changing out the meters made a huge difference in our revenue, bringing in $70,000 the first year," says Rogers. "In hindsight, that money is repaying the majority of the Rural Development Loan we secured to replace some infrastructure."

In 2008, Alliance implemented automatic meter reading as part of Phase 1, a 54-mile pipe replacement project. "If crews drove past meters in the construction zone, they replaced them with Neptune R900 radio-read units," says Rogers. "They installed 1,000 that year and it really jump-started the program. Now it takes one day to read the meters."

By 2010, all the meters met AWWA accuracy standards. The next year, 500 more meters received radios as part of Phase 2, a 20-mile pipe replacement project. "We'll be a totally radio-read district by March 2013 when we replace the remaining 220 self-read meters," says Rogers.

The replacement program recycles every 10 years for 10 percent of the units.

Tuning the system

During the meter change-out program, pressure switches governed water tower accuracy. "If something went wrong in the middle of the night, the tower overflowed and we'd lose quite a bit of water because there was no alarm system," says Rogers.

Alliance hired Navionics, a computer SCADA company, to connect the four towers and send alerts when they had anomalies. "During high winds and heavy rains, the system calls us 50 times, but that's okay," says Rogers. "We can see it's a communication problem and not an overflow or power failure."

The district had overlooked the Badger master meters in the past. Although they were in good condition, Alliance implemented an annual program to calibrate them for accuracy.

The same could not be said for the valves. Many were missing or lost, and those that remained had not been exercised. "There were no records," says Rogers. "We developed a program and our field workers identified, documented and downloaded GPS coordinates on all the valves."

One bad boy

With items two, three and four checked off the list, Rogers' team turned their attention to the final problem, the cracked or broken distribution piping. From 2001 to 2006, the district had more than 10 leaks per month. Although the system has one pressure zone with mains tied together equally, elevation differences enable some customers to have water pressures of 40 psi while others on the same line have 200 psi.

"We found the 200 psi leaks at the bottom of hills very quickly," says Rogers. "Those at the top of the hills were more challenging." To identify the primary replacement areas in the system, field workers originally used rented leak correlators, but the PVC pipes dampened sound, making pinpoint accuracy difficult.

Rogers reverted to old-school methods: dividing the district into zones, evaluating customer consumption, and calculating areas with the highest water loss. Then the crews volunteered to go out at 1 a.m., close the valves, and listen. "They tracked down leaks by walking the line," he says.

After staff added the numbers over two years to determine the replacement areas, local district engineer Klingner and Associates designed the projects. C&S Construction in New London, Mo., won both bids.

Vindication

In 2007-08, the Phase 1 project for $3.24 million upsized 4-inch mains to 6-inch SDR 21 or C900 PVC pipe wherever the line had volume or hydraulic issues, or the possibility of them. All work was open-cut, sometimes trenching right on top of the old main. Along one section, the excavation was kicking out a stainless steel repair clamp at each 10-foot glue joint.

"Over five years, we had repaired every joint for 120 feet," says Rogers. "Our funding agency was on site taking pictures and they were amazed. Seeing those clamps justified why we needed the loan."

Rocks again proved challenging, and required a rock trencher for more than a mile. "At one point, the rock was so hard that C&S advanced 50 to 80 feet per day for five days," says Rogers. Crews bedded the pipe on 6 inches of trucked-in soil or crushed limestone, then covered it with 6 more inches of the same material before backfilling.

"Klingner and Associates had a construction inspector on site at all times," says Rogers. "Our field workers operated valves and oversaw flushing to make sure the disinfection was completed correctly."

Phase 2 and beyond

The second project for $2.135 million upsized 2- to 6-inch mains to 6 inches and above to tie the middle of the distribution system to the outlying areas. Caldwell Tanks, a subcontractor of C&S Construction, built a 250,000-gallon water tower for additional storage capacity, then tied the towers together to improve hydraulic flow between them. They upsized those lines to 8 and 10 inches.

"The two replacement projects reduced our leaks to less than five per month," says Rogers. "They're tough to find because they are so small, but they represent the last 10 percent of water loss."

In 2011, crews evaluated 105 miles of pipe by closing the valves at night, listening, and walking the lines. Rogers is researching leak correlators while staff evaluates Phase 3. "The first two projects revealed some outlying issues such as 2.5- and 3-inch mains," he says. "They're spurs less than a mile, but we want them standardized to keep our repair parts inventory manageable."

Having overcome major water accountability challenges, the next big project for Rogers' team was working with the city to evaluate options that would provide customers with better water quality. They began by each investing $50,000 to conduct an engineering study to ensure the district would comply with reduced disinfection byproduct levels by October 2013.

However, the City of Hannibal's treatment plant, built in 1908, would not meet upcoming drinking water standards for  cryptosporidium, trihalomethanes and haloacetic acids. The district, city and Alliance are looking at options that include changing the treatment process, replacing the plant, or switching from surface water to groundwater because groundwater meets the current standard more readily.

"We're trying to establish a strategy based on what standards could look like in five years, then invest in ways to meet them today," says Rogers. "The cost of capital projects has doubled over the last eight years, so making the best decisions now will keep us compliant, while advancing and saving money in the future."



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