Always Shipshape

Whether for effluent qualit­y or basic maintenance and housekeeping, the Tomah (Wis.) Wastewater Facility gets consistently high marks

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Don Pierce will be the first to admit he’s “a fanaticabout cleanliness.” That explains why the Tomah (Wis.) Wastewater Facility, where he is plant supervisor, still looks brand new after 10 years.


Of course, Pierce and his team of five operators are no less meticulous about the quality of the effluent the plant discharges to the Lemonweir River. A biological nutrient removal process built around oxidation ditches helps the plant achieve greater than 98 percent removal of BOD, TSS, ammonia and total phosphorus.


Pierce and his fully cross-trained team monitor the treatment processes closely and, when challenges appear, share observations and ideas freely. They also keep the mechanical equipment reliable with a rigorous maintenance program, guided by a computerized maintenance management system (CMMS).


All that, along with effective sewer system maintenance and aggressive measures against inflow and infiltration, ensures high-quality, cost-effective service to the city’s 9,000 residents and a growing business community.


At a crossroads

Tomah lies in hilly southwestern Wisconsin, at the junction of Interstate 90 and 94. The community has grown in recent years with industrial players such as The Toro Company, Cardinal Glass Industries, and a Wal-Mart distribution center.


The city built its new 2.2 mgd (design) treatment plant in 1999. Besides seasonal BOD and TSS limits, it meets stringent standards for ammonia and total phosphorus.


Pierce rose to the plant supervisor position three years ago and has 25 years of experience with the city to go with nearly two decades as a sewer and water line installer in the private sector. As he approaches retirement, he holds his team to high standards, in part because one of them may ultimately replace him.


“I want all these younger guys coming up to learn our process well and get their Grade 4 licenses [highest level in Wisconsin], so one of them can take over when I’m gone,” Pierce says.

Besides running the plant, Pierce and his team maintain seven lift stations and 56.5 miles of sewer, much of it 60 to 70 years old, and 75 percent of it installed below the water table. “We’re working to replace older, problematic lines with PVC pipe,” Pierce says. “In the next two years, the city will bond about $5 million to replace about 50 blocks of sewer lines.”


Talented team

Some team members came to their jobs with especially relevant experience. Brandy Leis, a 12-year operator with his Grade 4 license, programmed and wired lift stations on a previous job. “He’s a real asset,” says Pierce. “He maintains our lift stations and does all the troubleshooting in those facilities.”


Brad Noth (Grade 4, five years) is an accomplished mechanic and takes the lead on equipment maintenance. The other operators are Mike Wetzel (Grade 4, 12 years), Rod Sherwood (Grade 4, six years) and Tom Beemis (operator in training, two years).


“Tom, Brad and Rod take one-week rotations on the sludge presses,” says Pierce. “Mike and Brandy rotate in the lab. We would like for everybody to be able to do everybody else’s job.”

The city helps operators get up to speed and advance in the profession. “When we first hire operators, we send them to the Introduction to Wastewater Treatment school, which is a six-day program offered at Western Wisconsin Technical College,” says Pierce. “We give them one year to study for and pass the test for their entry-level Grade 1 license. If they don’t pass, we can let them go — but we’ve never had that happen.”


He believes that’s partly because the job’s compensation structure motivates operators to stay. Each operator works five hours per day on every fifth weekend, earning ten hours of overtime, plus four hours per day of regular pay for standby duty.


As operators progress, the city sends them to the classes they need for their higher-level licenses and pays their exam fees (one time only — an inducement to pass).


Pierce likes to draw on the collective expertise of his team. “You have different people who watch different things,” he says. “We’ll sit down at the break table and discuss what we observe. We work together like a football team. I tell them, ‘If you see something that’s going a little haywire, don’t keep it to yourself. Tell everybody else, because someone might come up with a solution that will help us all out.’”


Removing nutrients

Pierce believes the team’s work is made easier by the plant’s EWT Carousel biological nutrient removal system, supplied by Eimco Water Technologies. “It’s a very consistent process,” he says. “The oxidation ditch will take a shock load. It’s amazing how well the process works.”


Four pumps (Weir Specialty Pumps - WEMCO) raise influent to the head of the plant, where it passes through a bar screen (Parkson Corp.) and a vortex grit removal system (Jones and Atwood, part of Eimco Water Technologies) and enters a 90-foot-diameter fermentation tank (Eimco Water Technologies), where biological treatment begins under anaerobic conditions.

The wastewater then enters a selector basin, where it is mixed in the absence of oxygen and phosphorus is released.


Next comes an anoxic basin where nitrogen removal occurs as the material is mixed to prevent solids settling. From there, the wastewater enters the front of the oxidation ditch, where mixing continues and dissolved oxygen is kept between 0.2 and 0.8 ppm. As it goes around the ditch, aeration is added and phosphorus uptake occurs. Dissolved oxygen at the back end of the ditch is kept at about 2.0 ppm.


From the oxidation ditch, the flow proceeds to the final clarifier (Eimco), where scrapers with spiral rake blades provide thorough mixing of the sludge blanket, which is maintained at a thickness of 2 feet. Activated sludge wasted from the bottom goes to three sludge tanks and then into the Class A biosolids process (see sidebar). Effluent from the clarifiers goes through a UV disinfection (Trojan Technologies) that uses 24 bulbs outfitted with an automatic cleaning system to reduce maintenance.


Pierce and his team keep a sharp eye on process parameters, often drawing their first clues from test results in the laboratory. Experience has taught them to adjust the process seasonally. “In winter, we’ll slow our wasting down because we need more bugs in the system to eat the BOD and TSS,” he says.


Running efficiently

While the process performs reliably, the plant’s efficiency has been enhanced by an aggressive program against I&I. “We recently completed an extensive sewer replacement, where we went through one part of town where the sewers were built during the second World War,” says Pierce. “We dropped 300,000 gpd infiltration.


“I’ve been here for 25 years, and our flow back then was 1.7 to 1.8 mgd. In early December, our flow on one Sunday was 840,000 gallons. For a week and a half during that month, we didn’t have a flow over a million gallons.”


Pierce attributes that partly to a rate increase that encouraged residents and businesses to conserve water. “It’s surprising that people are conserving that much,” he says. “Our engineers say that people are changing. It used to be that when we had a rate increase, everybody would lie low on using water for a month, and then go back to the same way they were. Not anymore.


“We have two oxidation ditches and two final clarifiers, and right now we only have one ditch and one clarifier online. The way people are conserving now, I don’t anticipate having to put that second ditch and clarifier on for another four or five years.”


Contributing to the plant’s efficiency and reliability is a CMMS from OPS Systems (now owned by Hach Company). “It organizes our entire maintenance program,” says Pierce. “Every week, we have 70 maintenance items to look at, from the Vac-Con Inc. jet-vacuum unit we use for sewer cleaning, to motors, to pumps.


“Of course, the software is only as good as the people behind it. The computer can tell you what to do, but it’s our job to get it done. We perform the maintenance, and as a result we have very few major problems.”


In 2005, the plant received a U.S. EPA Clean Water Act award in its region: second place for operation and maintenance among plants serving communities with populations under 10,000.


Ready to help

Maintenance includes general housekeeping, which Pierce insists upon. “Our landscaping looks good,” he says. “The plant is immaculate. I attribute that to our whole group. When the guys come in on weekends, they mop the floors and do general cleaning. If you don’t let it get grungy, it’s not a big deal to clean it up. Just because it’s a wastewater plant doesn’t mean it has to be dirty.”


While running his own facility effectively, Pierce is always willing to help his neighboring professionals. “We give a lot of waste sludge to neighboring communities if they need to sustain their processes,” he says. “Three or four operators call me now and then and say, ‘Hey, can you bring a load of sludge so I can reseed?’ I let them have it for nothing, because by giving it away we don’t have to run it through our press, and that saves us money. All I ask is that they pay for the hauling.”


Being a good neighbor is just another part of running a quality operation.


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