From The Ground Up

Team members in Spring Hill, Tenn., have had the privilege of being with their plant since the beginning. The results show in quality water and efficient performance.
From The Ground Up
Mike Burick (left) and Rex Lee, certified cross-connection operators, test the backflow at the Spring Hill plant.

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If Caryl Ann Giles and her team act like they’ve grown up with the Spring Hill Water System, it’s because they have.

“I came here before the roof was on the building,” says Giles, who arrived at Spring Hill 11 years ago and is now water superintendent. It was the city’s water treatment plant; Spring Hill bought water from neighboring communities for many years, and before the 1970s operated a simple gravity-feed system with a groundwater well, chlorination and storage tank.

“There were less than 1,000 people here in 1980,” Giles says. Spring Hill’s closeness to Nashville, along with construction of the General Motors Saturn car plant, fostered rapid growth. Between 2004 and 2007, the city grew from 13,700 residents to 23,450.

The new 4.0 mgd water treatment plant went online in 2003 and hasn’t missed a beat since. “We isolated the two connections we were purchasing from, started up, and we’ve had only minor issues since,” says Giles. “I’m not surec our customers even noticed a difference with the exception of increased system pressure.”

If the public hasn’t noticed, the profession has. The plant won the 2005 Award of Excellence for small systems from the Kentucky-Tennessee AWWA and in 2013 received the Award of Excellence for medium systems in both treatment and distribution, from the same organization.

Making it pure

Water for Spring Hill’s residential and commercial customers comes from the Duck River. The river is 284 miles long and home to over 50 species of freshwater mussels and 151 species of fish, making it one of the most biologically diverse rivers in North America.

At the intake, 6.5 miles from the treatment plant, Wallace & Tiernan chemical feed pumps (Evoqua Water Technologies) inject hydrogen peroxide to enhance oxidation of natural organic matter and limit disinfection byproducts in the finished water. Farther downstream, the utility adds powdered activated carbon for taste and odor control. “The water plant’s staff takes advantage of the contact time available in the 6.5 mile intake line to the plant,” says T.C. Norman, superintendent of finished water distribution.

At the plant, aluminum chloride is added as a coagulant before the raw water enters the flow splitter box. “We don’t use a flash mix tank,” says Jeremy Vanderford, assistant superintendent. The incoming pressure of the raw water and inline static mixer accomplish effective mixing. After leaving the flow splitter box, each treatment train’s flow enters an upflow Super Pulsator clarifier (Infilco Degremont), then passes through mixed-media Greenleaf filters (also Infilco Degremont).

Before the water enters the clearwell, a corrosion inhibitor is added, and the finished water is chlorinated but not fluoridated (the city discontinued fluoride feed about two years ago.

Coagulated solids and filter backwash material are pumped to a storage lagoon and then to the city wastewater treatment plant, about two miles away.

A SCADA system (Trihedral) monitors and controls the operation. The plant is staffed by nine operators who work three shifts, rotating in and out of the midnight shift. “We do all the maintenance ourselves, including changing oil, packing, even pulling motors,” Giles says.

Sending it on

To distribute finished water to its 12,800 service connections, Spring Hill maintains four above-ground storage tanks totaling 4.3 million gallons, five booster stations, and 198 miles of water main from 2.5 to 18 inches. The system has 1,400 hydrants and 2,300 backflows. The two larger tanks contain SolarBee mixers (Medora Corporation) to prevent stored water stratification.

Norman’s staff of five operators maintain the system, checking pump stations, dealing with customer relations, maintaining meters, detecting leaks and cross-connections, and flushing hydrants daily. The system has 100 percent radio-read meters; as they are taken out of service because of age or malfunction, they are being replaced with data profile meters that allow retrieval of up to three months of customer water usage information. About 40 percent of the original radio-read meters already have been replaced.

It’s a program that works, as evidenced by the recent plant and distribution awards. “The awards are based on record-keeping, equipment operations and maintenance, cleanliness of facilities and staff qualifications,” says Giles. “2013 marked the 10-year anniversary of the plant and system. There have been a few bumps along the way, but we’ve never been out of compliance.”

Good chemistry

Violation-free performance and association awards don’t just happen. At Spring Hill, Giles and her crew have taken a number of steps to improve operations and further ensure that customers receive the best water for their money.

The water plant staff, in addition to Vanderford, includes Brandon Gibson, John Lang and Garth McCrary, certified operators; Chris Bailey, Tim Westbrook and Stacey Jones, operators; and Ed Knowles, maintenance and operations.

On the treatment front, Spring Hill continues to study changes in advanced oxidation at its raw water intake. The river water contains a fair amount of natural organics, especially since the intake lies in a shallower part of the river, and the river can stagnate during the summer. Therefore, the process adds hydrogen peroxide as an oxidant. “We were adding sodium permanganate, but it’s much more costly than hydrogen peroxide,” says Giles. “We are also experimenting with dual oxidant feed to determine if there is a further reduction in TOC.”

While results have been good, the team continues to seek improvements and last summer tested ferric chloride in combination with hydrogen peroxide. “A number of plants have been trying it,” says Giles. “We conducted a three-week trial and had good results oxidizing organics. We had a 10 percent reduction at the plant and a 30 percent reduction in distribution system DBPs, as well as a reduction in raw water TOC.”

Spring Hill also analyzes daily for UV 254, a surrogate measurement of natural organics in water, using a Hach DR 5000 analyzer. “We saw an 18 to 19 percent reduction in UV 254 from the raw water at the river, to the water entering the treatment plant,” Giles reports. “With ferric chloride and powdered activated carbon feed, we realized a 30 percent reduction. We want to stay away from chlorine dioxide.”

The switch from sodium permanganate also made a significant difference in manganese levels, both in the piping systems and in the treatment plant. As for taste and odors, the powdered carbon addition seems to do the trick. “The river water can sometimes have a musty odor,” says Giles. “But we test frequently at the plant and have had no complaints here.”

The carbon is added half a mile downstream from the raw water intake. A small portable building houses a 400-gallon tank where the powered carbon slurry is mixed at a ratio of one pound of carbon per gallon of water. It is injected into the raw water at 5 mg/L. “We take advantage of the contact time as the water travels through the intake line to the plant,” Giles says. More contact time is achieved as carbon builds up in the plant clarifiers’ sludge blanket.

Directional flushing

Norman’s distribution team has been improving operations, as well. The staff includes Rex Lee and Mike Burick, certified in cross connection; Brian Love, certified in distribution; and Tyler Scroggins, distribution operator.

Norman reports excellent results with a change in the direction of the system’s flushing practice. “We start at the plant and flush outward, into the system, rather than flushing back toward the plant,” he says. The directional change yields better results and uses less water. “We’re pulling water with us, and we don’t waste as much that way.”

Since 2008-2009, Spring Hill has been using profile data meters (Badger Meter). Norman says the change has drastically curtailed the time his personnel spend reading the system: “When we were completely manual, it would take 20 people 2 1/2 weeks to read the entire system. Now with radio read, we can record our 12,000-plus connections in six hours, using just three people.”

The meters pull the previous 90 days’ worth of data. “When we have a customer complaint, we can show water use each hour, with a date and time printout. We can now verify volume and flow. It’s extremely helpful.”

Another important factor during design, construction and operation of the plant and distribution system has been Jerome Dempsey, P.E., with Dempsey, Dilling & Associates of Smyrna, Tenn. Says Giles, “He’s been the city’s consulting engineer for the past 25-plus years and has provided invaluable expertise with the design of the plant and water distribution system, along with operations and ongoing improvements and technical support for city staff.”

Home-grown expertise

Part of the pride Giles, Vanderford, and Norman take in the system stems from the fact that the Spring Hill team has learned by doing. “Everyone came here 10 years ago with essentially no water treatment experience,” says Giles, who started her water treatment career in 1979. “We hardly knew how to turn on the faucets, and when we did, we didn’t know the magnitude of the operation that was behind the scene.”

As employees came on board, they underwent six to eight weeks of intensive training, covering operation of the facility, the system and the laboratory, before they moved onto a shift. While the basic training had value, Giles maintains that the best learning is through experience. “After the training, you take a shift and build from there,” she says. “Just the other day, someone calibrated a chemical feed pump but didn’t shut off the suction valve. That’s when they realized they didn’t do it right. When people have actually done it, that’s when they actually get it.

“Day after day we do what is expected of us by our ratepayers. I don’t take that responsibility lightly, and our operators don’t, either. Every drop of water we produce has value as it goes out the door to our customers and ratepayers. It has value to our own families as well.”

More Information

Badger Meter, Inc. - 800/876-3837 - www.badgermeter.com

Evoqua Water Technologies, LLC - 866/926-8420 - www.evoqua.com

Hach Company - 800/227-4224 - www.hach.com

Infilco Degremont Inc. - 800/446-1151 - www.degremont-technologies.com

Medora Corporation - SolarBee / GridBee - 866/437-8076 - www.medoraco.com

Trihedral Engineering Limited - 800/463-2783 - www.trihedral.com



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