Remote but in Control

Operations team members at the Maryville Water Filtration Plant are proud of producing quality water and the steps they take to keep improving the process.
Remote but in Control
The Maryville team, shown near the flocculation sedimentation basins, includes (from left): Darrell Lewelling, senior operator; Eric Holder, chief operator; Jamie Dyer, relief operator; Keith Adams and Henry Hill, senior operators; Todd Hall, operator in training; and Doyle Prince, water and wastewater plant manager.

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Separated from their city by 5 miles, the six operators at the Maryville Water Filtration Plant in the eastern Tennessee foothills work as a tight-knit family to provide customers with drinking water that meets and surpasses all regulations.

Eric Holder, chief operator, has taught the staff about every operational detail, written procedure manuals for them from an operator’s perspective, and cross-trained them to handle any situation or emergency.

In 2003, the surface-water plant’s $3.1 million improvement project to address turbidity won the Award of Excellence for innovation and quality from the Rebuild Tennessee Coalition. Far from the limelight, Holder and staff continued to make major contributions, enabling the plant and equipment to operate at the highest level.

“Being a small staff, we take on numerous projects that many larger facilities would not,” says Doyle Prince, water/wastewater plant manager. “I give Eric a lot of credit for making that possible because he instilled a sense of ownership in the team. He’ll tell you they are just doing their jobs, but they continually do more than what is expected.”

In 2012, the Tennessee Water and Wastewater Association recognized their diligence with the Julian R. Fleming award for best water treatment plant in the state. Winners are chosen for having the best maintained and operated facility.

Conventional process

Drawing water from the Little River, the 6 mgd (design) plant delivers 3.9 mgd to 38,200 customers. Two 2,100 gpm Floway pumps (Weir Minerals) with 300 hp motors (GE Energy) deliver screened water 1,500 feet to the static flash mixer, which adds about 450 pounds of DelPAC 2020 polyaluminum chloride (PACl) solution (USALCO) per day, along with caustic soda and chlorine gas. The mixed water flows to two 78,100-gallon flocculation basins, each with three trains and fast-medium-slow mixers.

Flocculated water then enters two 353,000-gallon settling basins before flowing over the weir to four 288-square-foot sand and granular activated carbon gravity filters. From the filters, water flows to the 300,000-gallon clearwell and is finished with 132 pounds per day of chlorine gas, 141 pounds per day of caustic soda, 150 pounds per day of fluoride, and 35 pounds per day of polyphosphate. Three 2,100 gpm high-service Floway pumps deliver 3,125 gpm of finished water to the distribution pipes, three in-ground storage tanks, and four elevated storage tanks totaling 6.75 million gallons.

Operators use Hach equipment to monitor turbidity and feed PACl. They use a surface scanner at the river, turbidimeters at the plant, and a streaming current detector (Milton Roy) to control coagulants. Holder, who was promoted to the plant in 1999 after working nine years for the city, collects samples that one of three certified operators test for coliform and E. coli in the plant laboratory. Microbac Laboratories in Maryville handles tests that require a certified lab technician.

First in line

Maryville is the first plant to draw water off the river, which begins in Great Smoky Mountains National Park. Turbidity fluctuates from 1.50 NTU in dry weather to as high as 500 NTU when it rains. In 2008, operators switched from alum to feeding PACl. “It produces better floc in cold water, the pH doesn’t drop, and we don’t have to feed as much caustic soda because PACl isn’t as acidic as alum,” says Holder. “Those were big advantages, and they helped us immensely.”

Those weren’t the only changes the plant team made — they take pride in improving things wherever they see a need, and often with no outside help. A case in point was the replacement of a bar screen at the raw water intake that often clogged with leaves. “We decided to replace the screen in-house, and it was a hefty chore,” says Holder. “We ordered a wedge wire intake screen with 1/8-inch openings and assembled the parts.”

The staff waited until the river dropped below 8 feet deep, but by then it was January and the water temperature was 36 degrees F. Prince hired a crane to swing the screen out over the river, and a certified diver to position it with help from a staff member. “Eric is old school and will never ask somebody to do something that he won’t do himself,” says Prince. “However, there wasn’t a dry suit large enough for his 6-foot-6-inch frame.”

Prince suited up to help remove the bolts holding the bar screen to the intake pipe, maneuver it out of the water, guide the new screen onto the pipe, and tighten the bolts. They also positioned and bolted bracing for the intake screen. The entire installation took 90 minutes.

One giant leap

Holder and staff also installed an air compressor to blow leaves and debris off the screen. A sensor setpoint tells when the water level in the pump station wet well begins to drop, indicating that the screen is clogged. Hitting a button on the SCADA system activates the air compressor. “Improving the intake was an interesting project that really helped the plant and equipment operate as designed,” says Prince.

Mechanical obstacles were dwarfed by the challenge of switching from manual operations to a SCADA-controlled environment. The operators, accustomed to turning valves and flipping switches, had limited computer skills. “We had never dealt with anything like SCADA, so it was a steep and rapid learning curve,” says Holder. “But we hung in there and no one quit.” Holder not only mastered the system; he began readjusting setpoints to guarantee sufficient time for operators to respond to alarms.

“True operators are called on to do many different things,” says Prince. “When this team sees a need, they figure out what to do, then do it.” After the plant upgrade, they poured and finished a concrete slab on which they installed a metal storage building. Then an operator suggested it would be handy if the chlorine building had a loading dock for the 1-ton chlorine cylinders.

“We all jumped in,” says Holder. “We built a frame from 12-inch concrete block, poured and finished the concrete, painted it, and installed a safety railing.” Hiring a contractor to do the work would have cost the city $15,000.

Freeze prevention

When the plant switched from feeding lime to a 50 percent solution of caustic soda, the line would freeze at 53 degrees F. “The pipe runs 5 feet above ground from the chlorine building to the plant,” says Holder. “Over the years, operators have tried to insulate or wrap the pipe, but the caustic still froze occasionally.”

Henry Hill, senior water plant operator, suggested building a small concrete block enclosure over the exposed section. The operators dug the foundation around the pipe and poured concrete, and Hill laid the block. After sealing the structure against the chemical storage building, they cut a hole through the wall, allowing heat from the building to fill the enclosure. That eliminated the caustic freezing.

Energy improvements also are on the team’s radar. The operators expected the upgraded plant to use more energy, but they also knew energy was being wasted. To find out how much and where, Steve Davis, from the city’s electrical department, contacted the Tennessee Valley Authority to analyze usage.

“The raw water pumps and high-service pumps for finished water were running either wide open or they were stopped,” says Holder. The staff installed variable-frequency drives on the raw water pumps and on two of the three high-service pumps. “We’re really proud of that project and continue to enjoy the benefits of what we did,” says Prince. The plant now saves some $5,000 a month on electricity.

Never missed a beat

Prince is equally proud that during the renovation the plant continued to produce quality water with no violations. “That was a huge accomplishment,” he says. “The operators had to stay focused and not allow the commotion and upheaval to distract them. If they closed a valve or started a motor, they had to be aware of what problems that could cause in an entirely different area.”

During the renovation, Holder was always looking over the shoulders of construction workers or programmers, intrigued by what they were doing. “Eric has a very inquisitive nature,” says Prince. “He not only wants to know what something does, but how it does it. He takes nothing at face value.”

Holder’s thorough comprehension of the treatment process enabled him to help other operators better understand the plant. As the plant’s safety watchdog, he continually offers ideas on how to make the facility safer and employees work more safely. He also has served on the city’s safety committee.

“We appreciate Eric’s experience and leadership,” says Prince. “Those qualities have helped everyone achieve the highest level of excellence.”


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