Capital Domes

Washington D.C.

Words By Claire Howorth
Photos By Hochlander Davis Photography

Eight beautiful egg-shaped sewage treatment facilities will soon have a place in Washington, D.C.'s monument-filled skyline. These "digesters" will filter the area's sludge (the solid parts of sewage, called "biosolids" in polite waste parlance) by churning rods that swirl the waste as microbes eat away the bacteria. The sludge will be converted into soil fertilizer for area farmers and purified water that will flow into the Potomac.

At the Blue Plains Advanced Wastewater Treatment Plant in southwestern D.C., the new digesters—each measuring 303 feet at its waist and 108 feet in height—will process 350 tons of sludge a day. The new technology in the plant will decrease odor emissions, reduce the amount of treated sludge released into the environment, and produce enough methane in the process to provide 20 percent of the facility's power. The angle-free design is to prevent sediment from settling, saving around $16 million a year in cleaning costs. Similar plants are in various stages of construction in Boston, New York, Los Angeles, Baltimore, and San Francisco, but none are as aesthetically attuned as Washington's giant new ova.

Suman Sorg, the architect hired by the city to design the $311 million digesters, made sure that their appearance did not reflect their industrial and unattractive function. "The eggs," says Sorg, "will be seen not only from D.C., but from across the Potomac River and as you fly into Reagan National Airport. I think at night they will really look cool."

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