Tammy Hamblen rose quickly from street department employee to wastewater treatment supervisor and leader of a plant team.


Working 10 years for the Street Department in the Missouri city of Carrollton didn’t prepare Tammy Hamblen for her move to the wastewater treatment plant in 2006. “It’s two miles out in the country and I had to ask for directions,” she says. “I’d never been there.”

Attending the 12-day class for her Class D wastewater operator license changed Hamblen’s life. She was fascinated by how much there was to the treatment process: “I had found my career. It’s been a nonstop climb up the ladder ever since.”

The climb was faster than she expected. After only seven years at the facility, Mayor Bryan Mathis promoted Hamblen to wastewater supervisor. She wasn’t sure she was ready for the advancement, especially in the middle of a plant upgrade, but Mathis reassured her, positive that she would “do great.”

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Hamblen lived up to his expectations. In 2015, co-workers nominated her for special recognition at the Missouri Water and Wastewater Conference. The inscription on her Outstanding Supervisor award reads in part: “For 18 years of dedicated service to the water and wastewater industry and for leading her fellow operators by example, giving and receiving respect for hard work, dedication, and a job well done.”

Treatment train

Built in 1980 and upgraded in 2013, Carrollton’s 1.5 mgd (design) activated sludge plant treats an average of 980,000 gpd from 3,600 residents. Grit is removed as wastewater enters the main pump station in town. Three 70 hp pumps send the flow two miles to the plant. During rainstorms, three 25 hp pumps (all Flygt - a Xylem brand) send excess flow to a 1-million-gallon equalization tank next to the building. As the flow at the plant subsides, operators slowly release the contents of the tank into the system.

At the plant, wastewater passes through a grit vortex chamber (Kusters Water, a division of Kusters Zima Corp.), then enters three 30-foot-deep aeration basins, each with two cells and a blower. From there, splitter boxes direct the water to three final clarifiers. Secondary effluent is pumped to a UV disinfection chamber (Glasco Ultraviolet) and a Parshall flume before discharge to Wakenda Creek. Liquid solids from the clarifiers are land-applied or pumped to two anaerobic digesters, thickened and dried in eight beds before land application. Design biosolids production is 1,320 dry tons per year.

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Most laboratory testing is done in-house with various equipment. Inovatia Laboratories in Fayette handles tests requiring a certified technician.

Becoming a supervisor was a goal Hamblen had kept in the back of her mind. She took every class and test offered, knowing that older operators were approaching retirement and the city would need replacements. “Did I think I’d be promoted as quickly as I was? Never in a million years,” says Hamblen, age 41.

With little guidance from the previous supervisor or his assistant before they left, Hamblen used their files to teach herself what to do and how to do it. When in doubt, she called the state Department of Natural Resources, as regulation complexities surpassed the knowledge of her staff — two Class D operators and one laborer.

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Ace in the hole

“Our Street Department is the source for all wastewater personnel,” says Hamblen. “When I worked there, I cleaned sewers with Chad Winfrey, who became my best friend. Now he is one of the two Class D operators.”

The city owns a RamJet jetter truck (Vactor Mfg.) with 1,800-gallon water tank and 50 gpm/2,000 psi pump, and a FX25 trailer-mounted vacuum excavator (Ditch Witch) with 800-gallon debris tank. The first summer Hamblen and Winfrey cleaned sewers together, they pulled 15 tons of grit and gravel from the clay tile mains installed in 1938. They also rebuilt by hand eight disintegrated brick manhole chimneys. Winfrey joined the treatment plant in 2010.

As supervisor, Hamblen has made it a point not to ask workers to do something she won’t do. “If they have to go into the main pump station’s 40-foot-deep wet well, I’m going in first,” she says. “My guys appreciate that I lead by example and don’t mind getting dirty.” The pump station, built using components from the decommissioned 1980 wastewater plant, tested both of them.

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One night a 70 hp pump in the station went down. Hamblen, Winfrey and a laborer responded to an emergency call about sewage in the station basement. “Fortunately, the pump controls were upstairs, so we were able to shut down everything,” says Hamblen.

Following proper confined-space entry procedures, Winfrey and Hamblen went into the basement to close the inflow valve, but it was rusted tight. To reach the pump, the two waded through neck-deep wastewater, then removed the mounting nuts and bolts and attached the hoist chain. “We were working blind because we couldn’t see a thing,” says Hamblen.

Using the pulleys and chain upstairs, the laborer raised the pump, enabling the team to replace the bad impeller with one cannibalized from a defunct pump. Hamblen and Winfrey returned to the flooded basement, then used their fingertips to find the bolt holes and mount the pump. “It had to run,” she says. “Even though flow was low, sewage from town kept coming and the storage tank was full.”

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Winfrey is working toward his Class C license in collections systems and wastewater. “I’m 100 percent positive I could leave this place for a week and Chad could run it,” says Hamblen. Last July, on Hamblen’s recommendation, the city council promoted Winfrey to assistant supervisor.

Working supervisor

James Mason, the second Class D operator, has saved the city thousands of dollars by tackling many small electrical jobs and maintaining the pumps. “He’s been here five years, and knows a lot about how the plant operates and how to maintain those operations,” says Hamblen. “James is my Mr. Fix-It.”

His helper is often laborer Allen “Cookie” Jones, who spent 30 years at the Street Department before being transferred to the plant in 2014. “Cookie does exactly as he is told, and if he doesn’t know how to do something, he asks,” says Hamblen. When his rotation came to work in the laboratory, Jones was nervous because he wasn’t skilled in math.

After giving a pep talk, Hamblen took Jones into the lab and taught him how to test solids. “Cookie worked on that for a week until he was comfortable, and then we moved to testing pH,” she says. “Step by step, he learned how to do the test at each station, and he does them flawlessly now.”

While the plant’s daily routine is seldom mundane, it ratchets up when biosolids application season arrives in late September. “Once the crops are off the fields, we take turns hauling from daybreak to dark and through weekends until we finish near the end of October,” says Hamblen. “Fortunately, we don’t have far to go, as the fields are alongside the plant.”

Liquid solids are spread on 20- by 100-foot drying beds. If the beds are full, biosolids are stored in the 280,000-gallon digesters and from there land-applied as liquid. Once the digesters are empty, the crew removes the dehydrated biosolids from the beds; it is land-applied using a sander truck from the Street Department.

Addressing I&I

Hamblen and her team retain responsibilities upstream of the treatment plant. While the $7 million plant upgrade in 2006 was intended partly to meet higher disinfection standards, Hamblen believes the storage tank and a third final clarifier would not have been necessary if the city had addressed inflow and infiltration. When it rains, flows in excess of 1 mgd hit the main pump station.

One day in late August 2016, a supercell storm dropped 11 inches of rain. “Although we pumped as much water as possible to the plant and storage tank, it still poured over the wet well’s walls,” says Hamblen. Since then, the city has received a grant from the DNR to assess the collections system and prioritize repairs.

Hamblen was too distracted by everything going on at the plant to become suspicious when Mayor Mathis asked her to attend a meeting in his place and bring back the information. “He told me to spend the night in Jefferson City and to attend classes at the state Water and Wastewater Conference while there,” she says. “I knew nothing about the special award and was flabbergasted when I received it.”

Studying and working to master her new position on the ladder of success left Hamblen little time to believe bigger dreams were possible. Then two months after becoming supervisor, she had another life-changing encounter. A DNR wastewater facility inspector announced that he would arrive in 30 minutes. Rather than becoming a moment of despair, the meeting proved inspirational. “He spent two days helping me,” Hamblen says.

She discovered that the plant was making substantial headway. The previous inspection report had listed 30 violations. This time there were only eight, and she rectified them within a month. The experience gave Hamblen a glimpse into her possible future. “I would love to be an inspector,” she says.


Simple fix, big results

Operators at the Carrollton (Missouri) Wastewater Treatment Plant strive to improve efficiency while figuring out easier ways to do things. For example, they rely on eight 20- by 100-foot drying beds to handle liquid solids for most of the year.

One day it dawned on supervisor Tammy Hamblen that the beds seemed sluggish. A little research in the office files revealed the sand hadn’t been changed in 30 years. “We borrowed a backhoe from the Street Department and began removing sand and a little surface gravel,” she says. “Then we hauled four tons of new sand for each bed. The entire change-out took a year, but it made a world of difference. Now the sludge dries so much faster.”


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