Always Listening

Staff members’ ideas help turn the City of York (Pa.) treatment plant into a highly efficient, smooth-running, top-performing facility

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If you’re looking for general manager Steve Douglas at the City of York (Pa.) Wastewater Treatment Plant, you probably won’t find him in the office. More than likely he’ll be out in the plant, walking the rounds in jeans and a T-shirt, talking with his operators, asking questions and soliciting ideas.

His approach reflects an esprit de corps here that has made this 12-mgd (average) advanced facility one of the best in EPA Region III, if not the nation. “As managers, we don’t just sit around a table and talk,” he says. “We get out in the plant, and talk with our operators. We encourage their input, which we call Employee Initiatives. It’s not a formal program — it’s just part of what we do here.”

The approach works, as evidenced by the list of process im-provements and cost-cutting ideas implemented almost monthly. It also bolsters the self-image of the operators and makes them part of the success of the operation, factors that Douglas believes ought to be promoted as the wastewater profession attempts to recruit new talent.

Flexible processes

York, about 20 miles south of the state capital (Harrisburg) and part of the Chesapeake Bay watershed, is a biological treatment operation with a configuration that gives it great flexibility. It features three Kruger A/O anaerobic-oxic treatment trains. Train 1, a pure-oxygen activated sludge plant, was decommissioned in the 1990s.

Train 2 is made up of two flowpaths, each with one anaerobic and four oxic compartments. Train 3 consists of three flowpaths set up in a similar fashion as those at Train 2. This design allows for biological phosphorus removal, in addition to which the process converts ammonia to nitrates.

­Raw wastewater enters the plant through a headworks structure containing a pair of mechanically cleaned bar screens. A tandem of fixed bar screens is on standby for bypass conditions. Two grit chambers use differential settling rates to remove inorganic material and prepare the wastewater for biological treatment.

After primary clarification, about 42 percent of the flow passes to anaerobic-oxic Train 2 by gravity. The other 58 percent is pumped to Train 3. The primary effluent is then mixed with return activated sludge and distributed equally between the treatment train flowpaths.

Next, the wastewater flows through the anaerobic zone before entering the first of four oxic zones. While in these tanks, the water is treated for conventional pollutants as well as phosphorus removal and ammonia conversion. The configuration gives Douglas and his staff a great deal of flexibility to meet changing conditions and conserve energy.

“If I see 15 to 25 mg/l of ortho-phosphorus at the end of the anaerobic zone, I can expect to see around 0.3 mg/l coming out of the last oxic zone,” he reports. “Depending on flow conditions, we can take a train or a particular pathway out of service if we don’t need it, and thereby save on our energy consumption. It makes for easier treatment.”

Following treatment, the effluent from Trains 2 and 3 moves on to secondary clarifiers, and then to the advanced treatment section of the plant. A traveling bridge sand filter (Siemens Water Technologies) removes additional BOD and suspended solids, and a UV system (TrojanUV3000Plus series) disinfects the effluent before it cascades through a re-aeration channel and into Codorus Creek. The effluent achieves a minimum dissolved oxygen content of 5.0 mg/l. Because York is in a region with abundant limestone deposits, pH adjustment is not necessary.

Contractor takes the cake

Most of the solids accumulating in the secondary clarifiers are returned to the biological processes. The typical return sludge rate is between 20 and 25 percent of the plant influent flow, an adjustable amount based on laboratory analysis of the mixed liquor suspended solids (MLSS) and the sludge settling rates.

Waste activated sludge goes to flotation thickeners and then to anaerobic digesters for further biological stabilization. All solids removed from the five primary clarifiers are also sent to the digesters, where they are stabilized over 15 to 30 days.

Digester gas containing 65 to 70 percent methane fuels Caterpillar engines (one 1,150-kW, three 460-kW units) driving Kato generators to provide about 21 percent of the power needed for the treatment processes. Heat recovered from the engines is used in the digesters and to heat several of the treatment plant structures.

For dewatering, York uses centrifuges (Andritz) to obtain an 18-percent solids cake. Synagro, a private contractor, hauls the cake to area fields for beneficial reuse.

A major feature of the treatment plant is a Westinghouse distributed control system, which monitors and controls the facility. Special capabilities include controlling the speeds of the high-horsepower aeration and pumping equipment to prevent wasted energy. The computer system also controls the electrical generation system to reduce purchased-power costs. All large motors are powered from variable-frequency drives.

Employee power

As much as electricity and gas, employee ideas power the York facility. “We used to have a formal employee suggestion program,” says Douglas. “While that got us started, it was too impersonal. I’d rather talk to people and have people talk to me.”

Today, the plant uses an informal process of communication between management and staff that is as much a part of standard operating procedures as safety and environmental compliance. “We brainstorm a lot,” says Douglas. “We’re approachable. And we always let employees know what happened to their ideas. Basically, if it makes things easier or cuts costs, we’ll get it done. We believe that the only bad idea is the one that is never expressed.”

The list of good ideas and benefits derived from them over the last 10 to 15 years is impressive. In just the last few months, Douglas counts a number of key changes and improvements that have saved significant operational dollars while making life easier for the operators. For example:

• A leaf blower added to the sand filter dries off the track the bridge travels on, preventing condensation that would cause the wheel to slip, especially in cold weather.

• To avoid freeze-ups of the bar screen combs during the winter months, operators added curtain walls and old belt press media to act as insulation and help hold heat in the bar screen housing.

• Sliding gate operators added to the primary clarifiers mean the operator doesn’t have to get a mechanic to use a backhoe to slip a plate down the opening.

• Motorized gate operators make it easier and faster to open and close gates, especially critical during storms.

• An automatic sampler in the process return flow gives operators a better feel for plant loadings and makes mass balances easier to do.

• A UV-wiper testing system, developed by plant mechanics, allows the operator to see how well the wiper runs up and down the lamp shield when it’s out of the water. That makes it easier to spot and correct problems.

All told, Douglas estimates that ideas generated by operators and mechanics over the last several years add up to over $5.6 million in total savings. “We have a union shop here, but we’re all on an equal plane,” he says. “Bureaucracies simply delay good ideas.”

Working with engineers

Besides employee participation, Douglas feels a key to success is communication between plant operators and the engineering consultant.

“As you plan a treatment process, it’s really important that you get your operators involved in the design,” says Douglas. “It may take longer to do it this way, but you’re much happier with the end result. Also, you get a more practical design that’s tailored to the specific operating conditions of the plant.”

As examples, he mentions the skimmers on an old 145-foot-diameter clarifier. “No thought was ever given to the prevailing winds,” he says, “so the wind hinders rather than helps move scum to the scum box.”

Cleaning UV lamps is another. “Cleaning 728 bulbs by hand outdoors in the spring when it’s 40 degrees is not very comfortable work,” he says. “It wasn’t very long before operators put up a simple greenhouse that requires no heat but keeps the lamp cleaning area warm and comfortable.”

York is working with hometown firm Buchart Horn on the designs for coming upgrades. The engineering firm’s Larry Lutter says meeting with operators and soliciting their ideas is standard procedure for his company.

“We meet with the York staff on a bi-monthly basis to see what’s going on in the plant,” he says. “Then we’ll do our homework and come back with suggestions that might help make the operation smoother.”

Lutter says operator input is critical when his firm designs a new project. “We sit down with the staff first and see what works, what doesn’t, and what their needs are,” he says. “The final design is based on their input.” Lutter, who began his career as a certified operator, says not all ideas are practical from a cost standpoint, and there have to be some compromises. “But they are the people running the plant and making it work,” he says.

Get the kids interested

The environment of candor and responsiveness may be one reason Douglas feels so strongly about the worth of the wastewater treatment profession, and its attractiveness to young people searching for a worthwhile career. He wrote to TPO magazine recently about the need for the profession to work harder to bring new blood into the business.

“It just took us 14 months to fill a vacancy for a plant operator II position,” he says. One of the barriers is a local requirement that operators live within the city limits. He says the rule might have made sense in the past, but today, prospective operators like to live in rural areas and be outdoors.

“It’s an issue with us,” he says. “We’re an aging population. One-third of our people will be eligible for retirement in five years. There’s going to be a void.”

Douglas believes the profession is undersold. “It’s a good job,” he says, noting that treatment plant personnel earn good wages, have good benefits and job security, and gain the satisfaction of knowing they’re doing something to protect water resources.

“You’re outdoors a lot, or working with computers,” Douglas says. “That’s what makes it fun.” When school students visit the plant, he often asks them if they’ve ever thought of working in a treatment plant. “No one raises their hand, and then we tell them, ‘We never thought we’d be working here either, but we wouldn’t trade the job for anything else.’

“That’s one of my goals over the next year or so — to get out into the schools, and tell them what we do and how much pride we have. Everything’s going green right now. It’s a good time to get the kids interested.”


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