North Carolina Water Plant Team Members Earn Community Awards For Innovation

Water treatment personnel in a North Carolina city earn their fair share of the community’s annual awards for innovation.

The Innovation Awards Program may be unique to Hillsborough, N.C. Eric Peterson, town manager, started it in 2009 to recognize employees for exceptional contributions, ideas and efforts resulting in superior service or cost savings to citizens.

Anyone can nominate full- and part-time town employees throughout the fiscal year. A review committee selects the finalists, who receive Gold ($500 and one day’s vacation), Silver ($250) and Bronze ($100) awards or honorable mentions. The 2013 Silver award winners included six team members at the Hillsborough Water Treatment Facility.

Russell Bateman, plant superintendent (27 years with the town)

Howard Hobson, acting plant superintendent and chief operator (25 years)

Larry Williams (19 years), Steve Baker (16 years), Malcolm Hester (16 years) and Randall Lloyd (seven years), operators

Bateman and Hobson also won Bronze awards. All have Grade 3 (highest) water treatment operator certification. Williams, Baker and Lloyd are also certified laboratory technicians, and Williams and Lloyd were former superintendents at other plants.

“Eric came from a town that didn’t have a water or wastewater treatment plant,” says Hobson. “We’re a small town with both, so it was challenging for him to understand how everything worked.” In June and July 2013, the water division faced multiple obstacles during a dredging project at the Lake Ben Johnston reservoir. Assisted by the utilities division, operators provided quality service to customers through innovative plant management and operation.

Conventional treatment

The 3 mgd (design) water plant, built in 1972, was upgraded in 2005 with new raw-water and finished-water pump stations, a 1-million-gallon clearwell and three dual-media filters with air source. Finished water is delivered through 123 miles of mains to 14,700 customers.

The plant draws raw water into a 20-inch main via two vertical screened 24-inch intakes on the Lake Ben Johnston reservoir on the Eno River. After treating the water with 0.5 ppm sodium permanganate, two 44 hp pumps (all Floway pumps from Weir Minerals) deliver it 2,500 feet to the static flash mixer (Philadelphia Mixing Solutions), which feeds liquid alum and pre-caustic if needed.

Water flows from the mixer through three flocculation tanks (total 100,000 gallons) with Anco mixers (Enviropax) before entering two 250,000-gallon sedimentation basins. It then flows to three FilterWorx dual-media filters (Leopold – a Xylem Brand). The liquid drips through anthracite coal over sand with a Leopold IMS cap porous plate support instead of gravel.

Post-caustic, AQUA MAG blended phosphate (Alexander, a Carus company) and fluoride are fed to the finished water as two 100 hp/1,050 gpm pumps and a 200 hp/2,600 gpm pump send it from the 200,000-gallon pump well. Ammonium sulfate is added at 85 pounds per day as the water leaves the plant for four storage tanks totaling 6.45 million gallons. Except for Accumet pH meters from Cole-Parmer, monitoring sensors are from Hach. Operators make chemical adjustments manually.

Fluctuating levels

Controlling turbidity is a key operations challenge. Water from the 4-mile-long, 16-foot-deep Lake Ben Johnston averages 20 NTU in summer. Complicating matters, an “island” of sediment, vegetation and logs formed around the raw water intake 24 feet from shore. “We could see the entire island shift when we blew the intakes once or twice a month,” says Hobson. Within a day or two, mud was back on the screens.

As sediment increased in the lake, the plant’s ability to remove TOC decreased, enabling trihalomethane levels to rise above the average 0.057 mg/L. This was not the operators’ first brush with fluctuating THM levels. Shortly after the 1-million-gallon clearwell came online, its THM levels reached 0.087 mg/L. “We normally keep the clearwell less than half full,” says Hobson. “Nevertheless, the water just cooked until it was pumped to the system.”

At the time, operators fed chlorine at 2 ppm before the filters, then post chlorine after them. State consultants Mike Hicks and J.D. Monroe introduced a program to calculate chlorine contact times at different locations throughout the plant. They also moved the chlorine contact point from after the filters to between the clearwell and the pump well. The modifications lowered THM levels in the clearwell to 0.047 mg/L.

Alternative action

Dredging behind the dam was the only solution to the sediment problem, but the lowest bid was more than $100,000 over budget, prompting town officials to delay the project for six months. This increased the difficulty for operators in controlling THM levels.

To buy time until the dredging contractor arrived in June 2013, William Baker, assistant utilities director, suggested using the town’s trailer-mounted 40 gpm/2,000 psi Mongoose 402 water jetter to blast sediment away from the intake. To reach the pipe, Baker purchased and assembled two 8-foot-square floating dock sections to form a stable work platform. Then, as Sam Dunevant, utilities maintenance technician II, rowed a jon boat, Baker fed out 65 feet of rope and anchored it to trees on either side of the lake.

After hooking the line to the platform, Baker boarded it with the jetter hose and pulled himself hand over hand to the intake. Meanwhile, Dunevant stood on the bank and fed out the hose. Once in position, Baker signaled to Bryant Bailey, maintenance technician I, to start the jetter parked on the hill. For their actions, the team won Bronze Innovation Awards.

According to Kenneth Keel, engineer/utilities director, flushing the screens in April and May was the most significant factor in reducing THM levels at the plant. Other factors in reducing THM levels were dredging and moving the finished-water chlorine feed to after the clearwell.

Maintaining capacity

As the dredging date approached, plant operators anticipated purchasing water for two months from the City of Durham and the Orange Water and Sewer Authority. However, recent changes to both systems made them incompatible with Hillsborough’s. That meant turbidity would have to be controlled via numerous manual chemical adjustments.

“We already monitor our water every two hours instead of the required four hours,” says Hobson. “Once dredging began, we’d have to do it every 15 minutes and add a third operator to cope with the changes.”

Williams and Lloyd proposed another option: Why not fill the storage tanks and clearwell at night when turbidity was lowest, then shut down the plant when the night shift quit at 7 a.m. and pump from the clearwell during the nine hours of dredging? The solution lasted through the first week of May.

“Normally, we have drought in May, June and July, but 2013 was one of the wettest years on record,” says Hobson. “Every week for a month we had an inch or two of rain, interspersed with cloudbursts dumping 4 and 5 inches over three days.”

The rain overwhelmed the contractor’s two dewatering pumps set upstream of the dam to lower the lake level and expose more sediment. The only way to maintain the level below the spillway was if the plant drew water during the day. A half-hour after dredging began, operators watched turbidity levels shoot from 20 NTU to 400 to 700 NTU.

“We used as much chemicals for flocculation in two weeks as we normally use in a month,” says Hobson. “We were feeding pre-caustic at $4,800 per tank to boost alkalinity, then adding more alum at $4,500 per tank to optimize coagulation.” The normal alum feed rate of 32 to 36 mg/L occasionally reached 123 mg/L.

Throughout the dredging project, utilities personnel played key supportive roles for water operators. Earning Silver Innovation Awards were:

  • Nathan Cates, utilities inspector
  • Joel Lashley, utility maintenance technician III
  • Lacy Painter, utility maintenance technician II

Cates monitored turbidity in the river. He also met with the dredging contractor every morning and shared the daily agenda with the operators. “Everyone worked as a unit, enabling the contractor to meet the landowner’s July 31 deadline to remove the bypass pumps,” says Hobson. Throughout the project, the plant met the monthly average water demands of 1.5 to 1.6 mgd without imposing restrictions.

The dredging contractor removed 3,600 cubic yards of sediment from behind the dam. To accommodate the volume of mud reaching the plant, the 100-foot-circumference sludge drying bed needed a facelift. “It’s nothing but a big pond dug on a peninsula jutting into the river,” says Hobson. “After 23 years of neglect, the pond was full of sediment, vegetation and trees with 6-inch-diameter trunks.”

After a contractor cut down the trees, Lashley and Painter cleared the vegetation. They also searched for the two vertical 6-inch drains that discharged the pond’s decanted water to the river but never found them. Consequently, they excavated 12 feet down to the bed’s original depth and installed two new 6-inch drains.

“When the mud hit the plant, we ran the main and backup alum pumps simultaneously to keep up with it,” says Hobson. “That’s odd for us and a little scary. If one of them went down, it would mean a huge price tag to overnight a replacement – and that would be our best case scenario.”

Anticipating such events, the city replaces a pump every three years, usually the oldest one. Operators rebuild it for emergencies, but the spares aren’t always available on site. “More than once, we’ve had to borrow a pump from another department during a tense moment,” says Hobson.

Keeping it safe

Bateman and Hobson also received Bronze awards after David Moore, safety director, nominated them for introducing a new ammonia product. “We were using ammonium hydroxide,” says Hobson. “To enter the chemical feed room, we had to pass an annual physical and wear a self-contained breathing apparatus. In the last few years, only two people could pass the physical.”

Their research revealed many water plants preferring ammonium sulfate (Univar) because it is safe enough to use as a food additive and is almost odorless. The team tested a sample and received Moore’s approval to change the system. When it went online in spring 2013, operators found it effective and easy to use.

Although the product costs about as much as the original chemical, operators use more because it is less concentrated. They save money by no longer calibrating detection instruments and being able to dispense with safety gear.

“Receiving an award is never a one-man show,” says Hobson. “If it weren’t for my fellow operators and utility workers, a lot of this wouldn’t happen. It’s always a team event here, and every day brings a new challenge.”  

More Information

Carus Corporation - 800/435-6856 - www.caruscorporation.com

Cole-Parmer - 800/323-4340 - www.coleparmer.com

Enviropax - 801/263-8880 - www.enviropax.com

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

Leopold - a Xylem Brand - 855/995-4261 - www.fbleopold.com

Mongoose Jetters by Sewer Equipment - 800/323-1604 - www.mongoosejetters.com

Philadelphia Mixing Solutions - 800/956-4937 - www.philamixers.com

Univar - 331/777-6000 - www.univar.com

Weir Minerals - 559/442-4000 - www.weirminerals.com



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