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D.C. effort to clean rivers goes underground

Colossal tunnel aiming to solve sewage problem

A construction project takes place under Washington, D.C., with residents oblivious to its existence. A machine digs a tunnel, 6 feet at a time, which will one day carry raw sewage.

Jonathan Newton/Washington Post

A construction project takes place under Washington, D.C., with residents oblivious to its existence. A machine digs a tunnel, 6 feet at a time, which will one day carry raw sewage.

WASHINGTON — A massive machine — longer than a football field — is munching away beneath Washington like a giant earthworm. Before it’s done, it will devour about 2 million cubic yards of soil that has been sitting under the city since the days of the dinosaurs.

It is the most amazing and expensive construction project that no one ever will see.

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Like a creature from a sci-fi thriller, the machine will tunnel along — 6 feet at a time — beneath a city largely oblivious to its existence.

One day, raw sewage will roar through Washington’s tunnel, a vital project for a city that now pumps 2 billion gallons a year from its sewers and toilets directly into the Potomac and Anacostia rivers and Rock Creek. With a little help from upstream neighbors, those three tributaries may one day run closer to pure.

The tunnel will come within a center fielder’s throw of Nationals Park, within a corner kick of RFK Stadium, and nibble at the deepest roots from the National Arboretum.

It will go under railroad tracks that carry trains into Union Station and a six-lane roadway used by 60,000 cars a day, gnaw its way under Home Depot’s doorstep, and then chomp more than a mile and a half down Rhode Island Avenue toward Logan Circle.

The machine is a marvel of technology, an underground factory 443 feet long and almost six times the weight of the Statue of Liberty. It does about a dozen things at once, and it moves. Consider just one aspect of that movement: More than 100 feet below ground, how does it know where it’s going?

With a circular face three times the width of a Metrobus, what keeps the machine always within a few millimeters of its intended path?

Washington needs this new 13-mile long, $2.6 billion sewer tunnel because of what might be called, in hindsight, a dumb decision. Were they still alive to defend it, the city’s forefathers might respond much like people who wore bellbottoms in the 1970s or who dye their hair electric green today: It was the fashion of the day.

The “it,” in this case, was something called a combined sewage system. They were all the rage in 19th-century America. The District has one, as do more than 770 other places where 40 million people live.

That is a lot of flushes, and on a rainy day, that matters.

Here’s why: In a combined sewer system, your bath water, your laundry water, and whatever you flush goes into a network of sewers that also handles all the rainwater that flows down sewer grates from the street.

On a dry day, or one with a slow but steady rain, all of that combined wastewater heads obediently to the sewage treatment plant. In the case of the District, that is the sprawling facility called Blue Plains that sits beside the Potomac River in the southeast quadrant of the city.

But in a gully-washing downpour, a serious thunderstorm, or when 10 inches of rapidly melting snow gushes down the sewer grate, the system gets unruly. The path to the treatment plant becomes overwhelmed, and a filthy mix spews from 53 outlets into the three tributaries.

Not by accident, but by design. It’s not an occasional thing. It happens hundreds of times a year, contributing 2 billion gallons of untreated waste to Rock Creek, the Potomac, and the Anacostia, which gets the worst of it. All that unhealthy mess, of course, flows down into Chesapeake Bay on its way to the Atlantic Ocean.

“By 2032 our stated goal is to have water in the Anacostia that’s swimmable and fishable,” said George Hawkins, DC Water’s general manager.

Having the Potomac turned into an open sewer appealed to no one, and perhaps least of all to Lady Bird Johnson, who is said to have berated Lyndon about it when they flew into National Airport. That anecdote has relevance even today.

Though Lyndon B. Johnson had a war and civil rights on his plate in those days, the rumblings about pollution that began on his watch led his successor, Richard M. Nixon, to create the Environmental Protection Agency in 1970.

Fast forward 35 years. Everybody agreed that something had to be done about combined sewer systems, and the EPA and Justice Department ordered Washington and several other cities — including New York, Philadelphia, and Seattle — to stop dumping combined sewer overflow into rivers.

That gave birth to the District’s tunnel plan, and last year, the massive machine began to dig. They named it Lady Bird.

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