BETHEL – Call him a bug manager, or a turd farmer, but Jeff Warden, who is superintendent of the Wastewater Treatment Plant for the Town of Bethel, says it’s all about keeping the bugs happy.
Bethel uses what’s called an aerobic system, where natural organisms – or bugs – use oxygen to digest waste. Keeping the right balance of bugs is vital to keeping the system functioning, Warden says.
Its what is called an “enterprise fund,” explains Town Manager Loretta Powers. “Ideally it’s supposed to pay for itself, but we don’t have enough users.”
“The plant was redesigned and rebuilt in 1999 assuming a certain amount of growth per year,” says Warden. “But that didn’t happen. So now we have this process that can handle 340,000 gallons per day. Our average is closer to 90,000 gallons per day. So it’s also hard to operate it as designed because we don’t get enough flow in.”
“We use a biological process,” he explains. “We have a giant tank full of bacteria that do all of the work and there isn’t much food for them, so it’s a tricky balance. A couple years ago something came through the system and killed all the bugs. It takes a long time to grow them back. They are very sensitive; bacteria don’t like change. We have a sign in the office: Just remember we’re bug farmers. Ultimately, if they’re happy we pass our permit, no problem.”
The Clean Water Act 1972 freed up money to build rural infrastructure that no one could afford to keep up, Warden says.
“Aging infrastructure is my biggest concern,” he says. “A lot of this equipment is pretty old. We borrow a lot of money from USDA rural development. They give us loan/grant packages. We’re still making payments on the 1999 upgrade. Bethel is so fiscally conservative sometimes, which can be tough for us. All rate payers are taxpayers, but not all taxpayers are rate payers.”
It’s not a huge system. There are 550 to 600 residential and commercial connections to the system along nine miles of pipe – seven of which are gravity fed and the rest are forced from pump stations. Expanding the system would require adding pump stations, which are expensive.
“We don’t have that many problems,” Warden adds, “but like with many wastewater plants, the potential is huge.”
Highest on their list of concerns is the pipe along Mayville Road from the river to the old Forest Service building, which needs replacing. A camera run through the pipe showed missing chunks, misaligned sections, and other breaks. They may skip cleaning it this year, fearing it might do more damage than it solves. The plan is to replace it next year.
The Mill Hill pumping station is also in dire need of being replaced or risks overflowing into Mill Brook. Warden anticipates a price tag of $650k to $800k to replace it.
“It’s a rusty tin can in the ground,” says Warden. “Over the summer, we had a grease/rag plug cause an overflow through the sewer manhole onto the street.”
Warden, a master plumber for more than 20 years, has worked at Sunday River and the Bethel Inn before becoming the code enforcement officer in town. Four years ago he moved to the wastewater plant. He is part of a three-man team that includes Randy Autrey (10 years), and Toby Walker (also a former code enforcement officer).
Here’s a simplified overview of how the plant works:
Sewer lines enter the plant at the headworks building for primary treatment, where rags and larger chunks of waste are filtered out. Then heavy grit that washes into the system is removed because it creates too much wear and tear on the machinery.
In the next series of tanks, called the wet well, there is a visible rim and a floating island of grease. Once or twice a year, they have to get down in there and physically shovel out big chunks of grease.
Grease, wipes, and hair don’t break down in a biological process. And flushable wipes are not flushable. (There are numerous lawsuits over use of the word and the damage wipes cause to household and municipal systems.)
“That’s the interesting thing about being a wastewater operator,” says Warden. “On the same day, I get to look at bacteria in a microscope and then I get into safety gear and get all the permits and go down and shovel out a poopy hole. We also have a tractor. It’s an interesting job for the right person.”
After that, water is pumped to the oxidation ditch – an S-shaped channel, eight feet deep, that they call “the chocolate river.” Here, surface aerators help oxygen penetrate the water and keep the solids from settling.
The two white domes you can see from the road are called the secondary clarifiers, where the water slows down, and solids settle out.
Sludge is pulled from the bottom. Some is returned to the oxidation ditch, with added magnesium hydroxide used for alkalinity control. Bugs can break ammonia down but they require alkalinity and oxygen to do it, Warden explains. Lime is cheaper but less efficient and adds weight.
“Everything is interconnected,” he says. “We knew magnesium hydroxide was better (than lime) for the bugs. But it turned out way better than we expected. When we switched to magnesium hydroxide in July, the number of trips we had to make to haul solids dropped off.”
And because bugs reproduce, some sludge also need to be drawn off regularly in a process called “wasting.” This get dried out in the dewatering garage, built in 2019.
When it enters the dewatering machine, the sludge is roughly 1.5% solids, he says. Now with the dewatering machine, it’s 22% solids. The equipment has paid for itself in a short period of time because it dramatically reduces the solids they have to pay – and truck two hours each way to Unity – to dispose of when their trucks are full.
Back in the clarifiers, water is drawn off the top and treated with chlorine from mid-May to the end of September (swimming season) – but not rest of year – and then released to middle of the Androscoggin River, below Davis Park.
“Our capture rate for total suspended solids (TSS), compared to what comes in, is 98%. For BOD, or biological oxygen demand – meaning, if we release into river, is it going to absorb oxygen – that reduction is 99%. We’ve never had issues with heavy metals in our system,” he adds.
For its license from the Maine Department of Environmental Protection, the plant must test for BOD and TSS twice each month. They test once a year for mercury, twice a year for priority pollutants, and – since January – twice each week for Covid.
“We are well, well, well within our permit limits on what we can release,” says Warden. “We’re trying to see ourselves as environmentalists. The popular phrase in wastewater is ‘You get paid for your effluent.’ Whatever else is happening here is secondary to whatever is going out to the river. If that’s good, we’re good. But we have to get creative. If we can’t get a half million dollar piece of equipment, we have to figure out another way to get there.”
“Overall, Bethel is a well run facility with good effluent quality,” says Brian Kavanah, director of the Bureau of Water Quality for the Maine Department of Environmental Protection in Augusta.
Maine has 160 municipal and quasi-municipal wastewater plants. Bethel is a mid-sized plant (roughly half are larger and half are smaller). The plant’s license is up for renewal this year, and when renewed two additional months of chlorination will be added.
“Our process can’t capture phosphorous,” says Warden. “I’d love to be able to play with the reed beds and see how much they could absorb. It would be great to partner with schools and do some experiments.
Gould Academy science teacher Sarah Kamilewicz recently took her Environmental Science class to the wastewater treatment plant since their focus for the term was hydrology.
Students were surprised at the amount of cooking grease that goes down the drain and rises up as floating grease balls in the tanks, she says. They also noted the smell isn’t actually that bad as one imagines. They could even smell laundry detergent in the wastewater on their visit.
“It is a true eye-opening learning experience that wastewater treatment is not thought of on a daily basis,” says Kamilewicz. “Once water goes down the drain or is flushed away many do not think of the next steps of treatment before it is returned to the environment.
“Students cringed at the first bar screening station, but once they see the biosolids turn into fresh dirt and the clarity and quality of the water going into the Androscoggin at the end, they are appreciative of the science and workers behind this important treatment process.”
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