DC Installs a Green Sewage Infrastructure

D.C. Water, Washington's main water utility, announced a grand plan: Instead of creating massive tunnels to catch sewage overflow beneath the city's Potomac River and Rock Creek, they'll install green infrastructure

Columbia Heights, Takoma, Petworth and other neighborhoods surrounding the Rock Creek watershed will get rain gardens, bioswales (small planted areas installed just below grade), porous pavement, and green roofs designed to capture and clean runoff, totally replacing original planned tunnels. At the Potomac site, near Georgetown, there will still be a tunnel. But gravity, rather than an energy-intensive pumping station, will passively transfer the contents to the city's Blue Plains wastewater-treatment plant. That stretch will also get some new green infrastructure.

Green infrastructure's ability to absorb water where it falls has been proven to be effective, and to have a number of "co-benefits." After all, a lot of what we're talking about are trees, plants, and soil. Installing green infrastructure in strategic spots creates additional green space for the neighborhoods. That also means a reduced heat-island effect, improved air quality and health outcomes, more wildlife habitats, job creation, and increased property values. It's exciting news for the District, which will join New York City, Philadelphia, and a handful of other U.S. cities embarking on major green infrastructure projects.

But what about the Anacostia River? This less-famous river has, in particular, borne the brunt of environmental abuse over the years—though all of the District's waterbodies have been in infamously terrible shape since the mid-19th-century. At that time, the Washington Canal was D.C.'s dumping ground for waste. Fetid, disease-ridden sewage washed from the waterway, which connected the Anacostia and Potomac rivers to the Capitol via a center-city route, onto the marshy flats near the White House and flooded the National Mall during storms.

The canal was a health hazard, engineers realized, especially as the population surged in the post-Civil War years. But there was a solution:Combined sewers, one of the hottest infrastructure trends of the day. Wastewater and surface runoff were collected, transferred, and discharged together in a single pipe, below-ground. D.C.'s Board of Engineersdredged the Canaland built80 milesof these combined marvels.

That was only the beginning of the District's water woes. On very rainy days, the combined sewer system overflowed into the Potomac and Anacostia—by design. It does the same thing today, and that's a big reason that the Anacostia has been considered one of the most polluted waterways in the nation, despite flowing within spitting distance from the Capitol. Along the Anacostia's 8 miles, combined sewer overflows (CSOs) occur in17 different places. The neighborhoods that flank the river are historically some of the poorest in the district, a fact that has contributed to the city's neglect.

Source: City Lab

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Taxonomy

• Sewage
• Infrastructure
• Green Technology