On a Mission

The team in Norman, Okla., thrives on communicatIon, shared responsibilIty, and a clear, simple goal to deliver safe water at low cost to the community.
On a Mission

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Utilities superintendent Steven Hardeman says the Norman (Okla.) Water Reclamation Facility runs like a business. In truth, most businesses could learn a thing or two from the plant. Its operating platform includes:

  • A mission statement everybody embraces.
  • Job descriptions stated clearly in just three words.
  • Uncompromising commitment to product quality and customer service.
  • A makes-sense management style that puts operations at the hub of the communications and decision-making process.

"We have a product, stakeholders, customers, employees and a budget given to us by our customers," says Hardeman. "Our mission statement is simple: Produce safe water for the environment, at the lowest cost to our ratepayers."

It's more than words on a plaque. The facility produces effluent clean enough for recycle and reuse at the University of Oklahoma's golf course and for several in-plant processes. And the 24-member operating team has instituted energy-saving measures that have already lowered the plant's power consumption dramatically.

Teamwork, starting with the operators, is instrumental. "It used to be that communications centered around administration," recalls Hardeman, who has 25 years of experience as a clean-water professional. At Norman, ideas and recommendations emanate from anybody and are communicated throughout the team.

All ideas are considered based on the mission, and operators play a critical role in decision-making. "They are the ones who know what's going on; they listen, they hear, they see," says Hardeman. "They're in the center, with the support staffs around the outside, like a wheel. It's a different mindset."

High-powered secondary

The Norman facility may be one of the best-performing secondary treatment plants in the field. It has no disinfection requirement and uses no tertiary filters, yet it records typical effluent values of 0.1 mg/L for ammonia,
2.4 mg/L for suspended solids, and 4.0 mg/L for BOD.

Treatment starts with fine screens and vortex grit removal (both from WasteTech, a Division of Kusters Water). The flow then passes through a Parshall flume and splits on its way to two sets of primary clarifiers (Siemens Water Technologies and Hi-Tech, a Division of Kusters Water). The north plant handles about 40 percent of the flow, while the south plant takes the remaining 60 percent.

The clarified water is merged again and passes to the activated sludge system, operated in the plug flow mode and equipped with anoxic selector zones for nitrification-denitrification.

The plant was one of the first to incorporate such zones, back in 2000. "I'm amazed at how well they perform," Hardeman says. "The zones enable us to nitrify and denitrify, as well as control filamentous growth. We keep the dissolved oxygen low in the selector zones ahead of oxidation, and increase it to 3.0 parts per million in the oxidation zones."

Three trains are designed for 900,000 gallons each. Blowers are Gardner Denver, and Sanitaire (Xylem) supplied the aeration system. The design calls for mixed liquor suspended solids (MLSS) of 3,500 mg/L, but the Norman team likes to keep the levels around 3,000 mg/L. "We were higher during our sludge processing improvement project in 2008, getting up around 8,000 mg/L," Hardeman notes.

InsiteIG probes monitor mixed liquor and DO. The Norman staff has made adjustments to promote nitrification-denitrification during the colder winter months. "Our ammonia-reducing microorganisms don't like the cold, so we've had to add more microorganisms in the winter to sustain the desired levels of biological activity," Hardeman says.

After settling in a quartet of secondary clarifiers (WesTech and Conjet AB/National Hydro), the clear water passes through another Parshall flume, and some of the water is diverted for reclamation and reuse. The remainder is discharged to the South Canadian River.

Emergency cogen

Future plans include a disinfection and filtration station, followed by post-aeration, to improve effluent quality even further and meet a 2013 limit on fecal coliform. The plant will operate under an interim permit until 2013 while the new system is being installed.

Solids wasted from the system are pumped to gravity thickeners and then moved to anaerobic digesters by double disc pumps (Penn Valley Pump). Digester heat recovered via heat exchangers is used to bring feed solids up to proper temperatures. Most of the system components were furnished by Siemens.

While digester gas is normally flared, the plant maintains a cogeneration system (Waukesha Engine/GE Energy) to supply power during emergencies. There are plans to add more cogeneration capability in the future.

After digestion, solids are further thickened, then dewatered on Siemens centrifuges. A nearby 430-acre farm field accepts the dewatered cake at about 21 percent solids. In the winter, the material can be stored at the plant.

Return activated sludge is routed to an RAS/WAS station and then pumped back to the aeration basins. A new iFIX system (GE Intelligent Platforms) automates and controls plant processes, and enables remote monitoring. One SCADA node will be set up in the utility manager's office in city hall. Control of the city's 17 lift stations will be incorporated into the SCADA system in the near future.

Water for the future

Like many areas in the Southwest, Oklahoma has seen its share of droughts in recent years, and the Norman treatment plant is doing its best to make sure the community has an adequate supply of fresh water in the future.

"We have been practicing water reuse here since 1995," says Hardeman. "But we've had major droughts in 2005-06 and again in 2009-10. We're asking ourselves how we can help save our citizens water that comes from the lake (Lake Thunderbird, the city's main source of drinking water)."

So, since 2009, the Norman plant has been using effluent water wherever practical for in-plant purposes, like washdown of headworks equipment and seal water for pumps and motors. "We've been brainstorming and looking at other treatment plants to find new ways to use our water," Hardeman says. He estimates that the university uses 2 million gallons a month, and up to 7 million gallons a month during summer. At the plant, between 9 million and 10 million gallons are recycled each month, increasing to 14 million gallons in summer.

"That's water that we don't have to get from our water treatment plant, and it's water that's available for others to use," Hardeman observes. Meanwhile, the Oklahoma state legislature is working on new legislation that will encourage reclamation and reuse of water. Expect more reuse ideas from the team at Norman.

Saving energy

While water reuse represents economy at the Norman facility, energy reduction presents even more opportunities for the plant to live up to its mission of reducing operating costs and saving ratepayers money. Like many other water and wastewater operations across the country, Norman has been closely examining its electricity bills, searching for areas to cut costs.

"Normally, our electricity bills were running between $34,000 and $38,000 a month, and $28,000 to $34,000 of that total went to our aeration tank blowers," Hardeman reports. He and his staff looked into the situation and consulted with a local expert on power usage. They determined that their motors were running at peak kilowatt usage on a 4,160-volt system, irrespective of the air output. "We were squeezing down the air use, but the motors were running at 100 percent," Hardeman says.

The solution was to install variable-frequency drives. "We changed out motors and switchgear and converted everything to Square D [Schneider Electric] 480-volt VFDs," says Hardeman. "Now our air demand is based on the motor, not the valve."

Funding for the modifications came from the U.S. government stimulus program via a $1.1 million grant from the Department of Energy, and already the move is paying off. "We have seen a significant drop in electrical cost this year," says Hardeman. "We'll have to wait and see what the next few monthly bills look like before we have a celebration."

The Norman facility also looks for other ways to save energy. Sensor-based lighting has been installed throughout the facility so that lights go off when rooms are not occupied. In addition, modifications are being made to the digester gas and cogeneration system to further reduce the plant's energy bill.

Self-improvement

Like many other improvements around the Norman plant, the energy savings modifications are often driven by the facility staff. "We're always looking for ways to make things better," Hardeman says. "And we do most of it ourselves." The utility had budgeted about $50,000 for new chopper pumps in the clarifiers, but the plant halved that cost by installing the pumps with in-house labor. In another cost-saving measure, crew chief Mike Bates got online and found vendors that specialized in 4,160-volt equipment. "We sold the 4,160-volt motors and associated equipment to them for $26,500," says Hardeman. "We're proactive in what we do."

With the central role that teamwork plays here, staff communications are critical. "We've actually trained ourselves to communicate with one another," Hardeman says. "We have weekly, monthly and mini meetings. Our operators communicate with maintenance. When we do that, we can prevent breakdowns and fix something before it burns up and we have to replace it."

Communications at Norman extend beyond just the internal staff. Steve Rice, project manager for Garver, the engineering firm designing the next expansion of the Norman facility, spent several days at the plant. "It was extremely valuable," he says. "I went on rounds with the operators, talking with them and gathering input; they pointed to issues not even on the radar, and their suggestions made it into the final design."

An example involved new biosolids dewatering centrifuges proposed in the expansion.

"There were issues with the pumps that take the drainage from the centrifuges back to the head of the plant," says Rice. The meetings with operators pinpointed the problem, and the new design now includes an upgrade to the pumping station.

"We value their input," Rice says. "We don't want a situation where plant designers are identifying solutions without input from the guys who actually make the equipment work."

And what about those three-word job descriptions? "They're designed to provide each group with a simple way to remember their mission at the Water Reclamation Facility," explains Hardeman. For operators, it's Monitor, Collect, Input.

For the maintenance staff: Prevent, Repair, Maintain.

"We all do other things within our organization, but these are the core duties and responsibilities of each person," Hardeman explains.

And for him? Plan, Procure, Oversee.



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