The biggest public works project in the city’s history–a $94 million reconstruction and renovation of the wastewater treatment plant–is almost done, and it smells marvelous.

That’s the first thing to strike me on my third trip to the plant since 2009. On my first visit, the original West Plant, which dated to the 1930s, had deteriorated so badly that it had been shut down. That left the 1970s-vintage East Plant as the only thing standing between the city’s sewage and the Huron River.

When I came back in 2013, they were demolishing the old West Plant. Now, at the turn of the year, it’s almost completely gone, replaced by a brand-new West Plant. The new plant went online in November–and the smell that hung over the bend of the Huron River below Gallup Park is gone.

Mike Amicangelo, the plant’s senior utility engineer, starts my tour of the new plant at the end. “This is our final purifier,” he says, pointing to two huge round basins of calm water. “This is where the solids settle out. From here the flow goes to the tertiary filter building, and from there it goes to UV disinfection and then into the river.”

We next step into the blower building, where three massive machines blast the flow outside with oxygen. “We use one or maybe two [at a time], but we always have a backup,” Amicangelo shouts over the noise.

The blowers feed two new “trains,” interconnected tanks filled with roiling water where the oxygen hits the sewage. “You can look at it and tell if it’s working,” says Amicangelo. “When it rolls like that, you know you’ve got it about right. By starving the bugs [bacteria added to digest the sewage], as soon as they hit the oxygen they start consuming all the nutrients in the wastewater.”

A faint smell hangs in the air above the trains. It grows stronger as we approach the new splitter building, where wastewater enters the plant. Compressed by massive metal screws, it’s under so much pressure, Amicangelo tells me, that “if you were to cut a hole in that pipe, it would shoot fifty feet in the air!”

Amicangelo is overseeing the third great construction project in the sewage plant’s history. The original West Plant was built in 1936 by the federal Works Progress Administration. The feds also paid half of the cost of the neighboring East Plant in the 1970s. The new West Plant, though, was paid for entirely by Ann Arbor’s ratepayers–and there’s still more work to be done.

The first phase of the work, the Residuals Handling Improvements Project, started in 2009 and was completed in 2012 at a cost of $45 million. The current Facilities Renovations Project started in June 2012; now that the new West Plant is done, they’ll move on to refurbishing the East Plant, which should be complete around September 2017. After that, the utilities department hopes to replace part of the plant that purifies the city’s drinking water (see box, p. 28-29).

Something like the Flint water crisis won’t happen here because Ann Arbor has never used lead water pipes. But that doesn’t mean that we could never have dirty water pouring from the tap or sewage spewing into the Huron. That’s what all this rebuilding and renovating is designed to prevent.

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Inside the wastewater plant’s new administration building, Amicangelo shows me the new control room, where one guy is looking at a couple of computer screens.

“I was expecting a big control system,” laughs Amicangelo. “You can see what’s going on with every component in the plant and control it from that little computer. We’ve got these [computers] located throughout the entire plant, so 90 percent of the time this room is empty, because they can control it from wherever they are.”

The original West Plant, he says, “had more than gone past its useful life.” Since it went off-line in 2006, “we’ve spent about $69 million, and the [new] West Plant is essentially done outside of landscaping.” The project was on budget, but several months behind schedule.

“We had two very cold winters, so a lot of winter work got shut down,” says Amicangelo. “And we had soils with high metal content. It’s naturally occurring, but higher than [the state’s Department of Environmental Quality] limits, so you can’t just take this stuff anywhere.”

Hence the mounds of dirt outside the new plant. Naturally occurring or not, the high metal levels meant that the excavated soil would have to be landfilled if it left the site, at $10 a ton. “We were looking at an extra million dollars [in costs], so we cut a deal with the contractor,” Amicangelo says. “Instead of removing the soil and bringing in clean sand, we reuse it on-site, which means excavate, stockpile, build, and backfill with the same stuff. It’s cheaper but delayed construction.”

The plant was going through its testing phase during my tour. So far it’s passed. “We’re getting good numbers,” Amicangelo tells me. “Phosphorus is low. Nitrogen is good. It’s more advanced than the last system and more efficient at removing phosphorus and nitrogen.” In a later email, he adds that “[t]he new biological system is more efficient, consistent and reliable than the previous system. With a few exceptions resulting from construction activities, we consistently met our permit limits”–the maximum amount of pollutants that the EPA allows the city to discharge into the Huron.

Next up is the East Plant. “The whole electrical grid needs redoing,” says Amicangelo. “We’re replacing all the computer control systems, and more importantly we’re going to refurbish the aeration basins.”

How long till that’s done? “We gave it two more years,” Amicangelo smiles. “The contractor thinks a year and a half. So we wish him luck and do everything we can to help him achieve that goal!”

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Through it all, the plant never stopped processing wastewater. “We’re doing about eighteen million gallons a day,” says Amicangelo. “The highest [day] of the past twenty years was over seventy million.”

That was during the March 2012 storm that spawned the Dexter tornado. Unlike many older cities, Ann Arbor has separate sewers for wastewater and stormwater–but some buildings still discharge stormwater into the wastewater pipes. At the height of the storm, “we were pumping it into the retention basin, which is seventeen, eighteen million gallons,” says Amicangelo. “We had every train online, and we still couldn’t handle it.

“We got it under control, but some of it went down into the river. We weren’t fined because the DEQ understood that this was beyond our control.”

It could have been worse. Since 2001, the city’s footing drain disconnection program has diverted stormwater from almost 2,000 homes into basement sump pumps for discharge on-site. But several residents have sued the city over the program (see Up Front, p. 9), and it’s currently suspended for review.

At the wastewater treatment plant, at least, disconnecting footing drains remains popular. “Resumption of the program will only make things better here, as it will further reduce peak flows during rain events,” Amicangelo emails. “The change in the East Plant will be beneficial as well. It will take a lot of stress off our shoulders during the warm-weather months.”

The city built up nearly $60 million in reserves before starting the project; the rest of the cost is being paid for by bonds. To pay them back, the city has been steadily raising water and sewer rates for the past decade. The work is being done in stages because former utilities chief Sue McCormick “put limits on us,” Amicangelo says. “No more than 4 percent rate increase per year, for a total of 8 percent between the water department and us.”

After the East Plant’s done, Amicangelo figures the pumping stations are next. “We’ve got eight around the plant that are in poor condition. We’re maintaining them, but we need to start designing replacements. That should be small. A brand new station is under a million dollars.”

Amicangelo reckons the new West Plant will serve the city for most of the twenty-first century, “if we take care of it with upgrades and electric replacements. Your basic limit is the concrete.”

But that will be someone else’s problem. He plans to retire this month.

“I’m sixty-one now, and people say ‘You’re retiring too early,'” he says. “I say, ‘There’s a lot of stuff I want to do: work on the house. I’ve got ten acres between Dexter and Chelsea. I love wildlife, and I want to put in nesting boxes.”

As it turns out, Amicangelo’s home is on a septic system. “It’s only been cleaned once in twenty-four years,” he laughs.

Amicangelo used to be a wildlife biologist working for the federal government. Funding was so volatile that “you never knew if you would have a job or not,” he smiles.

Keeping the Huron River clean has been steadier work. “One thing people need no matter what is water,” he says. “It’s something they can’t do without.”

Water’sNext

The Wastewater Treatment Plant is the last stop in the city’s water system. The first is the Water Treatment Plant on Sunset Rd. And overhauling it is next on the city’s agenda.

The plant is surrounded by metal fences topped with barbed wire, and its gate opens only after a pleasant-sounding woman approves visitors over the intercom.

“Homeland security,” explains water treatment services manager Brian Steglitz. “You don’t want to be the utility that’s had a security breach, and someone contaminated the water supply.”

We meet in a low-ceilinged conference room in the main building. “The original plant was constructed in 1938, and there’ve been expansions in 1949, 1965, and 1975,” says Steglitz, who’s soft spoken and very serious. Like the sewage plant, the Water Treatment Plant is actually two parallel plants. The original can process twenty-two million gallons a day, while the second can handle twenty-eight million.

“Before the plant, there was an open reservoir on this property called the Chubb Road Reservoir,” Steglitz explains. “This whole area used to be apple orchards.” As it does today, most of the water came from Barton Pond, with a small supplement from wells. The only treatment was to disinfect it with chlorine.

Things are much more complicated now. Steglitz explains that the plant’s “heart and soul is primary treatment, which includes flocculation basins and clarifiers.”

Flocc-u-what? “Our water is particularly hard, so we are a lime-softening plant,” the civil engineer explains. “If we didn’t soften, people would be replacing their hot water systems more frequently than they already have to. Along with softening, you’re mixing chemicals in and creating this stuff called floc, which captures particles and settles them out in clarifiers.”

After flocculating and clarifying, the plant disinfects, filters, fluoridates, and finally distributes the water to 125,000 utility customers in Ann Arbor and parts of Scio and Ann Arbor townships.

“We have one of the more complex water treatment plants in the state,” says Steglitz. “It has to do with the nature of our water supply. With a river supply, water quality changes. If it rains, you have all this runoff coming off the roads and getting into the river. It affects the chemistry and the treatment process.”

Steglitz says they want to replace the older plant because “we have some 1938 technology that we’re still using.” In the clarifying basins, for instance, the water is stirred by wooden boards running on chains and sprockets–an antiquated system that requires constant maintenance. “We spend a lot of time trying to keep this functional,” Steglitz says.

The final filtering process, on the other hand, is right up-to-date. “Our filters are made of twelve inches of sand and eighteen inches of carbon,” Steglitz explains. “They can remove particles down to micron size.” Steglitz says that level of cleanliness compares well with the rest of the state. “We’ve won awards. People see us as leaders.”

Working with public services area administrator Craig Hupy, they’re currently studying what it would take to replace the oldest parts of the plant.

“It would probably be a couple of years’ worth of design and a few years’ worth of construction, so start to finish would probably be five years,” Steglitz says.

Assuming, that is, that city council approves: “The plan we’re proposing needs the support of council because there’s going to be a rate impact,” Steglitz explains. “It’s going to cost tens of millions … Council approved the study [and] the contract to hire a consultant, so they are aware.”

Steglitz says he’ll likely update council on the project this spring. If they get the go-ahead, work could start in 2017 or 2018. But even when it’s done, Steglitz says “people will probably not notice a difference.

“This is for future generations,” he concludes. With the updates, “We should be able to be here for seventy-five years.”