E-Mail This Article to a Friend The Tao of poo (continued)

There are four headworks in the Boston area: one at Columbus Park, in South Boston; one at Ward Street, in Roxbury; one at Chelsea Creek, in Chelsea; and one at Nut Island, in Quincy. Except for the newer Nut Island location, these facilities were all built in the 1960s, and all share an identical design. The Chelsea Headworks, located in a rundown neighborhood near the Chelsea River, is a squat, pinky-brown building roughly the size of a two-family house. Inside, the décor has the feel of grim municipality about it: moss-green wall tiles and mottled linoleum. As you enter the building, on your right is the control room, whose walls are filled with the kind of hardware you see in ’50s sci-fi films: dials, switches, gauges, flickering lights.

It takes a special kind of person to work at the Chelsea Headworks, especially to have worked here as long as Bill Harris and Roger Burly have — 15 and 11 years, respectively. Harris and Burly are large, solid-looking middle-aged men. Both sport varying degrees of facial hair, and both approach their job with a kind of defiant good humor. "We’re number one in the number-two business," says Harris. And then, pointing to a life preserver hanging beside what can only be described as a river of shit, "That’s to knock you out in case you fall in."

The river of shit passes through the headworks basement, a large, dimly lit room that hums with machinery and, at times, the roar of rapids. On a good day — or a bad day — 300 million gallons of raw sewage can flow through here. It comes in through a channel maybe six feet wide, churning and slopping against the walls, stinking to high heaven. The air in this room is recycled 12 times an hour, but still the guys who work here go home with an unsavory essence permeating their hair, their clothes, their skin. "Don’t touch your eyes!" says Burly after I grab hold of a bar to lean further over the river. Burly goes on to say that, even after he has showered and changed, he is cautious about ingesting any bacteria he may have picked up. "You know how you lick your fingers when you turn the pages of a book?" he asks. "Well, I spit on mine."

Shortly after entering the processing area, the river is channeled into three conduits, where it passes through filters called bar screens. These screens are designed to weed out anything from tree limbs to tin cans — anything larger than a tennis ball will not pass through. Every so often, an automated scraper lifts the contents from the screen and dumps them into a trough. Burly and Harris scrape this matter into a pipe, which carries it to a dumpster waiting outside. The stuff is pretty uniform in color — gray — and consists largely of tampon applicators, panty liners, condoms, rags, hair, and lumps of congealed fat, all wadded and matted together. Occasionally, they will get a dead rat. "They’re bald and bloated by the time they get to us," says Harris as I peer into the trough. "Look for a big purple thing."

At the tail end of the plant, the river of shit is funneled once more into a single conduit, where it churns and roils at the entrance to an outfall pipe. Because of the agitation, perhaps, the smell here is unbearably strong — the mere memory of it is enough to excite the gag reflex. As a friend of mine puts it, "You have smelled the devil’s ass." Burly and Harris, however, insist that you get used to this after a while — though Burly does add, "Somehow, I’m not in the mood for a Baby Ruth when I leave here." At the very least, theirs is a highly dramatic work environment, especially when the river, "still 100 percent poop," reaches the enormous outfall pipe, where it plummets 250 feet, with a Niagaran thunder, to another pipe below, one which will transport it to the Deer Island Treatment Plant, about five miles away.

The cluster of red-brick buildings at the entrance to Deer Island, each restored to its original 19th-century splendor, seems like something you’d expect to find in a tarted-up New England mill town. In fact, you wouldn’t be at all surprised to see a sign pointing the way to Ye Olde Candy Shoppe. Even the fact that one of the first signs you see says PRIMARY SCUM BUILDING doesn’t fully detract from the complex’s charm. What is immediately apparent — from both the pristine red bricks at the entrance and the massive, space-age structures beyond — is that a lot of money has been spent on this place. The second thing that strikes you is the odor hanging over the island. Or, more precisely, the fact that there isn’t any.

Indeed, if there is anything more impressive than the ingenious, intricate process by which the waste of 2.5 million people is treated here, it’s the lengths to which the MWRA has gone to conceal the grim realities underlying this process. There is barely any evidence at all that up to 1.3 billion gallons of raw waste can pass through this place on any given day. Indeed, I recently spent about five hours wandering around Deer Island’s 150-acre complex, and during that time I did not see one single piece of shit. Four billion dollars, it seems, will pay for a very effective, very elaborate sleight of hand.

The process itself is worth detailing, if only in a simplified fashion. First, the stuff is pumped up from its subterranean tunnels into a "grit facility," which, as its name suggests, sifts out granular material. Next, the waste is subjected to "primary treatment," in which it passes through four tanks, each of which is about three times as big as an Olympic-size swimming pool, called "slow-flow clarifiers." Here, the sludge — i.e., the poo — settles to the bottom of the tank, and the scum — condoms, panty liners, candy wrappers, fat, etc. — rises to the top to be skimmed off and taken to landfills. There is so much of this floating stuff, says Charles Tyler, Deer Island’s chief engineer, "you could walk on it."

Meanwhile, the sludge is whisked off to so-called digester modules. These egg-shaped tanks — 131 feet tall, 84 feet in diameter, and with a capacity of three million gallons apiece — are already a fixture on the Boston skyline. And they, more than any other aspect of the Deer Island plant, are responsible for the improved water quality in and around Massachusetts Bay. Until 1991, the sludge that now goes into the digesters was dumped directly into the bay, much of it, to the horror of local residents, bobbing back into Boston Harbor with the evening tide. Now, after spending a couple of weeks being worked on by microbes, the sludge is taken away on a barge, turned into pellets, and sold as fertilizer.

As for the condom-less, sludge-less wastewater, that passes through another series of tanks, where whatever organic materials that remain are fed on by what Tyler describes as "a biological community." After a few hours in these tanks, what remains are "fat and happy" organisms and water that looks pure enough to drink (it isn’t). Finally, there is a secondary skimming process to remove the last renegade panty liners and candy wrappers, this performed by people with hand-held rakes, followed by a disinfecting process, which basically uses double-strength household bleach to kill off whatever harmful bacteria is left.

It’s impressive to view the end result of all this: a seemingly endless series of open-topped tanks, each containing rows of two-sided waterfalls. You’d be happy to have one of these things in your back yard. From here, the water plunges, in a roaring torrent, 420 feet down into a massive outfall tunnel, where it flows 9.5 miles out into Massachusetts Bay. Even now, the effluent doesn’t simply get dumped into the ocean. Over the last mile and a half of the outfall tunnel are 55 diffusers — objects the size and shape of an Apollo re-entry module — each of which is fitted with dozens of nozzles that disperse the water quietly and harmlessly into the sea.

And so the journey reaches its happy conclusion. About three days after I flush my toilet, my muck is on its way to a farmer’s field somewhere, and the water that washed it away is tickling the limbs of starfish. The end result of this vast, insanely elaborate game of Mousetrap is itself remarkably simple: people can go to Carson Beach and Constitution Beach and Wollaston Beach without encountering the chicken vindaloo I had for dinner the previous night. And that, for everyone concerned, is a very good thing.

Chris Wright can be reached at cwright[a]phx.com