Working the Land

While putting plant operations first, team members at a Tennessee treatment plant teach themselves how to apply biosolids and produce a crop.
Working the Land
Native grasses and wildflowers surround the Harpeth Valley plant.

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From a distance, the Harpeth Valley Utilities

District’s (HVUD) wastewater treatment plant could be mistaken for a farm. That’s because it is a farm.

Nestled on 400 acres along Tennessee’s Cumberland River, the plant produces more than 4 million pounds of Class B biosolids, which the operators apply to the land by injection. They prepare the ground and buy and plant the seed to produce a crop for a local farmer.

The 10 mgd activated sludge-extended aeration facility is run by a team of eight who do everything from farming to NPDES permit compliance testing and plant operation and maintenance. It’s a demanding job, and they do it well.

Annual BOD averages 3.16 mg/L, and TSS averages 4.2 mg/L (permit levels are 30 mg/L). They have won awards too: Plant superintendent James Pendleton earned the 2007 Operator of the Year Award from the Tennessee Association of Utility Districts, along with the 2012 William D. Hatfield Award from the Kentucky-Tennessee Water Environment Association.

Although biosolids land application is a large part of their days, the staff members are operators first. “The majority of time may be spent on the farm, but everyone has to put plant operations ahead of everything else,” says Pendleton. This attitude, along with teamwork and excellent communication, are the keys to success. “What makes it all work is the people,” says Pendleton. “I am really proud of the HVUD team.”

Newer plant

Built in 2001, the treatment plant sits in a rural area, minutes from downtown Nashville. It serves more than 13,000 customers in Davidson, Williamson and Cheatham counties and treats almost 2 billion gallons per year. The district also operates and maintains 220 miles of sewer lines and 29 lift stations. Plant equipment includes:

  • Three fine screens (Parkson Corp.)
  • Two Carousel oxidation ditches (Ovivo) with 6.93-million-gallon aerator volume plus anoxic zones
  • Two 160-foot-diameter secondary clarifiers (Schreiber)
  • Three return activated sludge screw lift pumps (Schreiber)
  • TrojanUV4000 disinfection system
  • Three aerobic digesters (Ovivo)
  • Wonderware SCADA system (Invensys Operations Management), integrated by M/R Systems

The team added a Hach LDO dissolved oxygen sensor and sc200 controller in one of the oxidation basins in spring 2012 to improve reliability and reduce maintenance. The plan is to replace the other three sensors with the same model in 2013.

During the first year after startup, the plant purchased a TerraGator vehicle (AGCO) to land-apply the biosolids. In 2012, the team added a 4600-gallon Balzer injection tank, pulled by a New Holland tractor. The savings were significant and the additional application rig allowed them to maximize biosolids application.

The new equipment has streamlined the operation and doubled production during favorable weather. “The equipment is loaded with liquid biosolids at a centrally located point on the property,” says Pendleton. “This maximizes efficiency, as we are able to reach all application sites in a shorter time.”

Learning about biosolids

The plant started land-applying biosolids in July 2001. Operators injected the biosolids in liquid form using the TerraGator. “It seemed logical to land-apply, since we had a large tract of land next to the plant,” says Pendleton. “It meant the operation could be self-contained – everything that came into the plant left as effluent or was converted to grass.”

The plant team worked with the Tennessee Department of Environment and Conservation (TDEC) to get approval for the land application sites and educated operators about federal and state regulations. “We had to become familiar with concepts like agronomic loading rates, management practices, site restrictions, and pathogen and vector attraction reduction,” says Pendleton.

The plant has met both goals. “We constantly test the quality of our biosolids, and we are able to keep up with the amount of material and where it goes,” says Pendleton. There is no biosolids permit in the state, but the NPDES permit language directs permit holders to comply with federal 40 CFR 503 regulations.

“Although the Water Environment Federation has formal classes in biosolids land application that are offered nationally and worldwide, every site and soil has its own characteristics,” says John Brown, HVUD general manager. “We designed a training program that would meet the district’s needs, while preserving the environment.”

The biosolids operation runs year-round. During summer, material is applied mainly to fescue fields. The Bermuda grass fields are higher and dryer, allowing application in fall, winter and spring. “Land application opportunities are less frequent in the winter, but we use this time to catch up on maintenance,” says Pendleton.

Doing it all

“We have specialists on staff, but all operators can perform every job,” says Pendleton. “An operator may perform plant operations today, and tomorrow be land-applying, working in the lab, or doing groundswork and painting.”

Everyone is cross-trained, according to lead operator and laboratory manager Albert Solberg. “They all have to learn how to run digester samples in the lab. After a little training, they pick it right up.”

Pendleton, who has been with the utility for 26 years, 12 at the treatment plant, holds a Grade IV wastewater license and Grade II wastewater collection and water distribution licenses. Solberg has been with the plant for 10 years and holds a Grade IV wastewater license. His duties include overseeing NPDES permit tests, and he developed the plant’s laboratory quality assurance/quality control program from the ground up. Other staff members are:

  • Operators Ryan Williams (5 years, Grade III) and Chris Maheu (7 years, Grade IV)
  • Operator/maintenance worker Nicholas Tatum (2 years, Grade III)
  • Operator trainees Jimmy Victory (12 years), Cody Raley (one year) and Ronnie Edmondson

Williams assists with NPDES laboratory analyses. Maheu serves as the wastewater treatment plant safety coordinator, maintaining Material Safety Data Sheet (MSDS) files for the entire facility, including the lab. He also conducts monthly safety meetings. Operator trainees are involved in land application. The staff members are encouraged to attend biosolids conferences and learn as much as possible about the subject. They also take seminars and courses, such as activated sludge and basic math.

Stepping up

The plant is successful largely because of the staff’s caliber. “None of them came from a wastewater treatment background,” says Pendleton. “One came from a large retailer, two others from a maintenance background, and the other three from factories. We look for responsibility and a good work ethic. We can teach wastewater operation or lab technique, but we can’t teach character. Each person brings that with them the first day.”

Williams came from a manufacturing background, and received his Grade III certification after joining the plant in 2007. “He’s developed into a real asset, capable of performing practically every task we have here,” says Pendleton. “When Albert suggested training someone to help with the NPDES laboratory analyses, Ryan was the natural choice.”

Operator trainee Victory joined the plant as a maintenance employee and handled all the plant maintenance for 10 years, adding biosolids and farming. When maintenance and land application became too much for one person, Tatum took on maintenance.

“Nick was already a journeyman pipefitter and had some mechanical aptitude, and more important, he displayed the ability to take on responsibility and was self-motivated,” says Pendleton. Tatum handles as much maintenance as he can and coordinates the rest with utility machinists, electricians, SCADA and PLC experts, and the vehicle mechanic.

“A lot of mentoring is going on at the plant,” says Pendleton. “When we hired Ronnie Edmondson in early August 2012, we asked Ryan to take responsibility for training Ronnie to do lab work, plant operation and land application. Ryan has done the job very well, and it allowed him the opportunity to be a mentor.”

Mutual support

Pendleton is modest about why he won the Operator of the Year and Hatfield awards: “I am fortunate to be surrounded by good people. I am supported by my supervisors and the plant’s staff. I think I won because the people here do such a great job.”

He credits Solberg with much of his success: “Albert and I share the load of directing day-to-day operations, and developing strategy for the future. That includes workload scheduling and deciding when and where to apply biosolids. Our mutual support provides stability to the operation that carries over to the team.”

Teamwork and the ability to meet a challenge head-on are other reasons for the plant’s success. In summer 2011, seven scrapers in the plant’s two clarifiers became badly worn and needed replacing. “As a team, we discussed whether to contract the work out or tackle it ourselves,” says Pendleton. “We opted for the latter.”

They planned the installation for July and August when low flows and minimal rainfall allowed one clarifier to be offline. “We had to coordinate how quickly to drain the clarifier, as doing it too fast would have overwhelmed the return activated sludge pumping system,” says Pendleton.

They drained it over a day and a half, overlapping all shifts. The staff also made sure replacement scrapers were on hand. They emptied and washed the clarifier, inspected it for defects, and made sure a crane and operator were available. The utility’s machine shop inspected the work before the clarifier was placed back in service.

Moving forward

Beyond operating the plant and the farm, the team has helped enhance the local environment. “We’re one of the last undeveloped properties in Nashville, and we have all kinds of wildlife: deer, wild turkeys, bald eagles and a variety of waterfowl,” says Pendleton. “The fact that we operate a successful biosolids program while providing a habitat for wildlife shows that doing one does not necessarily exclude the other.”

Establishing native grass habitats at the treatment plant has long been general manager Brown’s vision. “John and I met with John McClurkan of the state Department of Agriculture and discussed our desire to develop some acreage for this purpose,” says Pendleton.

McClurkan referred them to Joey Woodard of the nonprofit Tennessee Wildlife Resources Foundation. “Joey introduced us to Brian Flock, who is with the Tennessee Wildlife Resources Agency,” says Pendleton. “He surveyed our property and came up with a plan to start developing a wildlife habitat on a little over 40 acres.”

The plant team prepared the ground in late fall 2011, killing the fescue and Bermuda grass so that native seeds could take hold. In spring 2012, they began planting seeds of sideoats grama, little bluestem, lanceleaf coreopsis, purple coneflower and other prairie plants. Native habitat takes several years to establish.

“It’s difficult to put a pretty face on a wastewater plant, but, if you’re a wastewater operator, you have a great opportunity to be one of the best friends the environment has,” Pendleton observes. “We don’t want to operate at a bare minimum, but to set an example for the people who follow us, while providing a safe and beneficial wildlife habitat for years to come.”

Farming on the Side

Staff members at the Harpeth Valley Utility District Wastewater Treatment Plant are operators first and farmers second. Besides operating and maintaining a 10 mgd activated sludge-extended aeration facility, the plant’s eight operators land- apply about 4.3 million pounds of Class B biosolids. Stabilized material is injected into the soil at agronomic rates based on nitrogen content.

The operators do it all, from preparing the ground to buying and planting the seed for the wheat, fescue and Bermuda grass. The plant has an agreement with a local cattle farmer who cuts, rolls and transports the hay to his farm.

“There are no landfill disposal costs or liability, we don’t have to leave the property to land-apply, and we raise a beneficial crop. It’s a very green way to do business,” says James Pendleton, plant superintendent.

Wheat and fescue are planted in fall and harvested in early summer. Bermuda grass is planted in May and harvested in mid- to late summer. Wheat is sown as a cover crop that grows through the winter, protecting the fescue seed.

“Good communication is vital for planning the farming operations,” says Pendleton. “Purchasing seed and other supplies, preparing the ground, and the ultimate harvesting of hay are planned well in advance.

“We operate our plant and our solids program, and maintain a sanctuary for wildlife, all within minutes from an urban area. In the future, we hope to continue to enhance and expand this concept. Where will the future eventually take us? I don’t know, maybe a forest?”


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