To Save Money, They Built A Membrane Treatment Plant

A Tennessee utility district builds an award-winning membrane water treatment plant, saving money and ensuring a quality supply to meet rapid growth.
To Save Money, They Built A Membrane Treatment Plant
Membrane filters at the J. Isom Lail plant yield high-quality water. Tom Flynn, assistant plant manager, is shown performing a pH analysis and alkalinity test with an Oakton Ion 510 Series multimeter (Cole-Parmer).

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Eleven years ago, the South Blount County Utility District was buying potable water from two utilities in neighboring cities. This posed problems: increasing costs and the possibility of water shortages, especially in summer.

When the price of water from one supplier more than doubled over two years and the number of customers increased by a third, the district had to act. In 2004, the district commissioned its own water treatment plant, the first in eastern Tennessee to use membrane filtration for a municipal water supply. Today, the J. Isom Lail plant in Maryville provides an average of 2.6 mgd for 14,300 customers.

The plant benefits from exceptionally pure source water (0.4 NTU turbidity) from Lake Tellico, a hydroelectric reservoir in Blount County. The operating team solved a lead and copper issue in 2011 and went on to win the 2014 Award of Excellence in the midsize treatment plant category from Kentucky/Tennessee AWWA. The utility has saved some $100,000 per month on water costs since it built the plant.

Treating its own

The district began providing water service in 1958 to 1,300 customers and purchased water from neighboring communities until September 2004. “Our district manager, Isom Lail, had a vision to begin treating our own water,” recalls Danny Gregory, plant manager. “He presented his idea to our board commissioners, and they agreed. We had to lay 30 miles of new waterlines, but it was worth it.”

Plant construction began in 2002, and the facility went online in summer 2004. Besides the membrane filtration system (Pall Corporation) and UV disinfection (WEDECO), the $20 million project includes:

  • ClorTec sodium hypochlorite generator (Severn Trent Services)
  • Cal-Flo lime system (Burnett Inc.)
  • Carbon dioxide tank (Tomco2 Systems)
  • Three large air compressors (Atlas Copco)
  • SCADA system (MR Systems)

The engineering firm that designed the plant recommended the membrane technology. Preliminary water sampling and a pilot study showed that microfiltration followed by UV would do the best job.

“Isom and our commissioners talked to several membrane companies and liked the membrane plant’s small footprint compared to a conventional plant,” says Gregory. “They also liked the finished water’s low turbidity [average 0.02 NTU] and the system’s low maintenance.”

The UV system enhances log removal of parasites and helps ensure that the plant can meet future disinfection rules. “We get great log reduction credits with the microfiltration system, but the UV gives us one more log credit, for a total of 8.5 credits,” explains Tom Flynn, assistant manager.

The engineering firm selected the pumps, and plant operators choose the valves and laboratory equipment. Since 2004, the plant has added or upgraded some equipment:

  • 120 membrane filter cartridges for more capacity
  • Turbidimeters (Hach 1720e) 
  • Additional UV bulbs and programming
  • SCADA programming

Training the team

Since the J. Isom Lail plant was the district’s first treatment facility, it had to hire and train an operations and maintenance team. Danny Pardue, lead operator, came on board in January 2004, along with Eugene Durant, maintenance supervisor. Operator Danny Davis was also hired at that time, while Flynn, David Borum, Luther Crass and James Lawson joined a few years after plant startup. Pardue had worked at a conventional treatment plant, and Flynn at a membrane plant.

Gregory, a 15-year district employee at the time, helped train the team. “Before the plant went online, Pall came to the facility and conducted hands-on training,” he says. “Now, they visit quarterly to answer questions. Learning the system is a never-ending process. We make notes when we have a question so we can ask when they stop by.”

Says Flynn, “Although the plant is 10 years old, we still run into new situations, like changing cleaning recipes on the filters because of water temperature changes, or valves not closing fast enough. Pall comes in every quarter to calibrate the system and check valve programming and recipes. This plant is so high-tech. A conventional plant looks like a swimming pool, but we never see the water in this plant, since it’s pumped from the lake and goes through the system. Fortunately, the system can’t produce bad water.”

Training on the UV system involved learning how to clean the quartz sleeves and change the lamps. Pardue came from a plant with a manual system and had to learn how to operate the SCADA system; Pall and MR Systems provided that training.

Getting the lead out

In 2006, the district’s drinking water exceeded the 15 ppb U.S. EPA standard for lead — the concentration sometimes went as high as 110 ppb. The source turned out to be corrosion from lead-rich pipes and solder in older homes.

The district invited Dr. Marc Edwards from Virginia Polytechnic Institute to conduct a nine-week study to solve the problem. Water from the plant was subjected to various phosphate inhibitors, disinfection with free chlorine and pH adjustment to simulate nine different conditions. A solder-copper coupling was then exposed to each water sample.

It was Flynn who contacted Edwards after the plant team had battled the problem for five years. “It was a slow process, and Tom saw it through to a successful conclusion,” says Gregory.

Recalls Flynn, “The study concluded that dosing with orthophosphate would bring us in compliance with the lead and copper rule. Additional studies showed that the lead levels were significantly reduced, indicating that the orthophosphate treatment effectively reduced solder corrosion in the system.”

But then, SBCUD noticed a rise in lead leaching out of brass in household plumbing. “Virginia Polytech noted that orthophosphate had not been shown to control lead leaching from brass,” says Flynn. “They recommended adding liquid lime and carbon dioxide to the orthophosphate to obtain an alkalinity of 40 mg/L at 7.6 pH.” The new treatment protocol went into effect in June 2011, and within six weeks the lead and copper in all 40 samples fell below EPA standards.

Winning awards

The district’s total of 37 team members take pride in their work and the facility’s appearance. “We all work well together,” says Gregory. “Most of us started at the bottom and worked our way up, so we take pride in what we do.” The plant is staffed around the clock with two operators per shift. The operations team meets once a week to review operations and discuss budgets, the employee handbook and personnel issues. Gregory and the district leadership team strongly encourage staff input.

For the 2014 excellence award, the plant stood out from among 150 midsize facilities in the state. “They looked at a number of things, including our state sanitary survey score, our maintenance program, employee training and emergency plans,” says A.L. Scott, district assistant manager. In 2013, the district received a perfect score on the Tennessee Department of Environment and Conservation sanitary survey, a two-day inspection of the plant from intake to delivery at the customer’s meter.

Says Pardue, “The excellence award was the result of things we do every day, like running tests in our laboratory, routine cleaning and alternating our pump operation every few days or at least once a week. Preventive maintenance is important — Eugene [Durant] does a great job.”  

“Our biggest maintenance challenge is training,” says Flynn. “A maintenance staff has to be well trained in electrical, programming, pumps, motors and plumbing, and it’s a struggle sometimes to find training schools in each field for them.”

Most team members have many years of experience, and a few have worked for the district for more than 30 years. Gregory has been with the utility for 19 years, and Flynn, who holds Class 4 water treatment and Class 2 water distribution certification, has seven years with the utility. Besides those already mentioned, the team includes:

  • Distribution employees Kenneth Bully, Norman Clark, David Dyer, Melvin Farmer, Stacy Gregory, Shannon Icenhower, Michael Jackson, Allen Lail, William Long, John Myers, Christopher Payne, Michael Russell and Larry Teaster
  • Maintenance/sampling specialist Shannon Boring
  • Backflow prevention specialists Quentin Caldwell and William Thomas
  • Collections specialists Stephen Boring and Ronnie Hutsell

Planning for the future

The plant has plenty of capacity for growth. “We are getting about 16 new taps a month, but of course we’re not growing as fast as before the economy fell,” Gregory says. “We’re running at around 3 to 5 mgd today, and we’re designed for 8 to 12 mgd, which is plenty.”

The utility’s greatest challenge will be keeping up with regulatory changes and finding qualified operators. “I see THM and HAA5 limits becoming more stringent,” Gregory says. “We’re already working on lowering those levels.

“As for qualified operators, right now we have little turnover, but some of our people are planning to retire. The certification test is very difficult, since they changed it a few years ago. The state has to do something to attract people to the industry and make it easier for them to become certified.”

Staying proactive is key, Scott observes. “I think what sets us apart from other utilities is our proactive approach to doing business. We strategically plan for line replacements, infrastructure improvements, plant maintenance and additions so that we will always be prepared to handle our customers’ current and future needs.” 


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