“In my business, we always need three pumps–two pumps and a standby,” says Mike Amicangelo. “And we get very nervous when one of the two pumps goes down and we’re running on standby.”

Amicangelo is senior utility engineer at Ann Arbor’s sewage treatment plant, and he’s been nervous for the last year. To understand why, hold your nose and follow him into the venerable West Plant.

Built by Roosevelt’s WPA back in 1936 on a bend in the Huron River east of Dixboro Road, the plant processed three generations of Ann Arborites’ wastewater–all the unmentionable stuff that’s gone down our sinks, drains, showers, toilets, sewers, and in some cases manholes. But the city shut it down last January.

Outside, the huge primary settling basins have ragged cracks, and their massive concrete foundations are crumbling. Inside, the pumps that moved the sewage are silent, and there are dried sludge and pigeon droppings on the floors. It’s dingy, dusty, dirty and above all smelly–because even with the temperature below freezing on this frosty winter morning, the stale but stinging stench of decades of filth and excrement hangs in the air.

“The West Plant’s offline not because we want it to be, but because it’s got to be,” says Amicangelo. “Because even if we did repair it and put it back online, it wouldn’t meet current standards and it would be continually breaking down.

“I use the analogy of a rusted eighties pickup truck. You keep putting parts into it, but it keeps breaking down because it’s so old-so old that pretty soon they’re going to stop making parts for it, and then what are you going to do?”

Next door, in the solid waste removal building, the stench is much stronger. The mammoth plate-and-frame machines here work round the clock, squeezing waste from water. But here, too, are signs of creeping decay: some of the stainless steel holding vats have corroded straight through. Water oozes and drips through the holes, like a slow-running sore.

Most of the equipment here dates to the mid-1970s, when the newer East Plant was built. More than forty years later, these facilities, too, are far from young. And, as Amicangelo points out, since the West Plant closed, the East Plant is all that stands between the city’s sewers and the Huron River.

Any failure of the East Plant would be offensive, environmentally irresponsible, and extremely expensive–fines for discharging untreated sewage can hit $25,000 a day. As Amicangelo says, “For reliability–and reliability is crucial–we’ve got to have a new West Plant.”

Amicangelo, an amiable fifty-four-year-old Detroit native, has been cleaning up Ann Arbor’s wastewater for twelve years. “I was in the private sector before that, about ten years as an environmental-civil engineer and about seven years as a wildlife biologist with federal agencies,” he says. “After a while, I just hated getting on a plane every week and flying off somewhere.

“I took a big cut in pay to come here, but I love it. For a guy like me,” he grins, “it’s like having a huge chemistry set to play with.”

It’s a chemistry set with weighty environmental consequences. “The flow never stops,” Amicangelo says. “It comes in twenty-four seven. We usually handle about nineteen million gallons of wastewater per day. We can handle up to 29.5 million gallons, but sometimes we get more than that–one day last week, we got 34.8 million gallons because of rapid melt-off.” (Though storm runoff is supposed to go into a separate system, many buildings discharge it into the sewers.)

“Now, the system can only handle so much, so when that happens, we equalize the flow with the retention basin,” he says, pointing to a vast featureless concrete building enclosing three giant tanks that can hold up to seventeen million gallons of untreated wastewater. “When the water does enter the system to be processed, it first goes to the lift station”–where huge screw pumps raise it fifteen feet–“and after that, gravity does the rest.”

Treatment begins in a pair of huge metal vats. The water is unspeakably filthy and the stink is eye-watering, but if it bothers Amicangelo, he doesn’t let on. “This is primary treatment, where we screen the grit out,” he explains. “We get all sorts of stuff coming in, mostly sanitary napkins, tampons, and condoms. But we’ve also had cinder blocks and even two-by-fours-all sorts of stuff gets dumped down manholes. So first we have to run the water through metal screens”-foot-and-a-half-long steel teeth-“that rake the solids out, and then we bag them and send them to the landfill.” The solids used to be incinerated, but the plant’s incinerator was shut down in 1997.

Next, thankfully, it’s back outside, where the screened sewage flows into four round tanks, each 100 feet wide and holding 600,000 gallons. Here it sits for about nine hours, while the solids gradually drift to the bottom. From there the water flows into four dozen 200-foot-wide rectangular concrete tanks. From this point on, the engineer explains, the treatment process is a “biological reactor” that uses microorganisms as the active ingredients.

The first tank is calm; the organisms at work here are anaerobic, that is, they don’t require oxygen. “But look at what happens when we blast them with air,” says Amicangelo. The surfaces of the rest of the tanks writhe and bubble like witch’s cauldrons, as air bubbling up from the bottom feeds the oxygen-loving bacteria at work here. “That’s them consuming the biological materials producing biomass,” explains the engineer cheerfully.

“After that, we add the secondary clarifiers to settle out biomass,” continues Amicangelo. This takes place in four circular tanks, each 120 feet in circumference and holding 900,000 gallons of freshly treated water–and dozens of happily splashing ducks. “That’s how clean the water is after we add the secondary clarifiers,” he says proudly. “You and I might not want to go in, but the ducks love it!”

The “secondary solids” removed by the clarifiers–so called to distinguish them from the “primary” solids screened out up front–are thickened then treated with lime “to bring the pH up to twelve to destroy pathogens.” Then they pass through the big presses in the solid waste removal building. “We apply it as soil amendment–really more of a soil conditioner–that gets used like cow manure in farm fields all over Washtenaw County and out in Jackson County,” Amicangelo says.

The cleaned water, meanwhile, flows onward into a series of raised tanks in open metal sheds lined with banks of electrical equipment. “Now, at this point, most municipalities just take the water, treat it with disinfectant, and put it into the river,” Amicangelo says. “But in Ann Arbor, we run the water under an ultraviolet light. This doesn’t kill the microorganisms, but it does stop them from reproducing.”

The last thing Amicangelo shows me is the Huron east of the plant, downstream from the plant’s discharge point. The river’s rapidly rushing waters look and smell crisp, clear, and fresh–especially after viewing and smelling the primary treatment building’s waterborne horrors.

It hasn’t always been this way. Nobody now with the city knows for sure, but before the West Plant was built, Ann Arbor presumably used the easiest, cheapest method of disposal: discharging its sewage straight into the Huron.

The WPA plant was a big step forward, and it worked well enough for its time. But between 1950 and 1970, the city’s population more than doubled, and Ann Arbor ran out of capacity to treat its sewage.

“We’d reached a real crisis in the early seventies,” recalls former mayor Lou Belcher. “We had a moratorium on development in the city. Plus, we were getting huge fines from the EPA for dumping raw sewage into the Huron whenever it rained hard enough.”

City council debated joining the “super sewer” project–a huge expansion of Detroit’s sewer and water systems–but ultimately opted out. Instead, the city agreed to split the cost of a new wastewater treatment plant with the federal government. That had a big upside–it would cut the city’s share of the estimated $55 million bill in half–but also a big downside: it meant the city had to play by the feds’ rules, which included taking the lowest bid.

The contractor who got the job, says Belcher, “was notorious for being late and for running up his bill after he got the contract.” But the feds insisted, he says, and “in the end, the project was months late and the price went up to one hundred million.”

The city’s share of the project, funded by bonds, jumped from $27.5 million to $50 million. “It was a very unhappy experience,” Belcher says.

This time around, capacity isn’t the issue. It’s simply that the facilities are falling apart and out of date.

“We ignored the infrastructure in the nineties–the storm water system, the water treatment plant, and the wastewater treatment plant-and now we have to play catch-up,” says city council member Stephen Rapundalo. “The council back then put it off and put it off and put it off until it became our problem.”

This time, says Rapundalo, the impetus came not from council but from public services administrator Sue McCormick. “I met Sue when she first came on board,” Rapundalo recalls, “and her take-charge attitude was a breath of fresh air.

“Sue has taken a real close look at the system and provided a detailed and rational analysis for an integrated wastewater system that will improve services [and] provide cost efficiencies and increased environmental standards.”

McCormick, smart, direct, and earnest, came to Ann Arbor from the Lansing Board of Water and Light. Replacing the West Plant and refitting the solid waste removal building weren’t part of her initial brief. But a few years into the job, McCormick says, “I began hearing from the front line people that the equipment was bubble-gummed and rubber-banded together, that they were doing reactive maintenance, not preventative maintenance.”

McCormick eventually proposed two extremely ambitious and extremely expensive building projects: gutting and refitting the solid waste removal building with up-to-date equipment, then demolishing and rebuilding the whole West Plant. At a total estimated cost of $140 million, the combined projects will be far and away the biggest civic building project in the city’s history.

How can a city that’s laying off staff afford to spend $140 million on sewage? The short answer is that sewers are paid for by user fees. That means the system isn’t subject to the strict tax limitations that restrict spending on everything from police officers to parks. And because state law bars cities from diverting user fees for other purposes, it’s not subject to the tense tradeoffs that mark the rest of the city budget.

Asked how the projects are going to be paid for, McCormick has a simple answer: “They’ll be funded by bonds,” she says. “And the bonds will be paid for by the users.”

Under McCormick, the city has been increasing the sewage rate gradually, by about 4 percent a year. No individual increase was so big that the citizens would take to the streets in protest-indeed, the project enjoys unanimous support on City Council. But they’re already adding up to real money. When the increases began four years ago, customers paid $2.35 per 100 cubic feet. By the time the last scheduled hike takes effect in 2014, the cost will be $3.27. The result is that even as the rest of the city budget shrinks, the wastewater budget is flush-McCormick says it has $39 million in cash reserves and user fees are generating an extra $5 million a year above operating costs.

At the planned rate of spending, the reserves will be exhausted sometime next year–leaving the city needing to borrow close to $100 million. Despite the current credit crunch, city administrator Roger Fraser emails, he anticipates “no particular problems getting the bonds approved by council or sold. Standard & Poor’s just upgraded our rating (on a storm water issue) from A+ to A++.”

“We’re aware these will be extremely expensive projects,” McCormick acknowledges, “and we’re trying to find help paying for them. . . . We will pursue all avenues to reduce the costs to our users.” She says the department has applied for federal stimulus money, “but we think bridges and streets are going to receive those funds–which we think is good. The Stadium [Boulevard] bridge is a forty-million-dollar project that needs to be done soon, or it’ll be so restricted by weight it’ll be a walkway.”

Back at the sewage plant, work began in March with demolition to make room for a new solid waste removal building. The existing “equipment is worn out, and we’ll be lucky to get through two years without it breaking down,” Amicangelo says. “So we have to do that first.” They’ll remove the unused incinerator, rebuilding the area it occupied with new plate and frame machines, and then refit the rest of the building.

Then it’s on to the new West Plant, with a hoped-for start next February. The project should take five years.

“But when we’re all done,” concludes Amicangelo, “we’ll have a system that’ll be good until 2025”–when it’ll be time to replace the East Plant. But a new generation of engineers will have to worry about that one. “By that time,” Amicangelo laughs, “I plan to be retired.”