More Than You Want to Know About the Eco-Impact of Snowmelt
In case you didn't notice, there's a lot of water decorating the District of Colombia these days—many inches of it, frozen into piles on every street and beside every sidewalk. With sunshine and temperatures headed into the 40s later this week, the water's about to make its way into the city sewer system.
That's the province of the D.C. Water and Sewer Authority. Last Friday, LL spoke to its newbie general manager, George Hawkins, who says the the melt doesn't stand to stress WASA's system too much. But it is a good time to check whether your neighborhood storm drains are clear of ice and debris—lest water form pools, get cold, and "you end up with a hockey rink."
There is also an under-appreciated environmental aspect to this, Hawkins notes—which is that as the snow melts, dirt and oil and bits of tire and other pollutants come with it—not to mention tons and tons of salt. That leads to a small amount of hydrological irony.
The oldest parts of the city, which have what considered to be an antiquated sewer system, are actually comparatively enviro-friendly compared to the newer parts of the city. That's because the old sewers are "combined sewers"—both sanitary sewage (from sinks, toilets, etc.) and storm runoff (from street catchbasins) go to WASA's Blue Plains treatment facility, located at the city's southern tip. There, Hawkins says, "It gets one of the best treatment processes in the world."
But in the newer parts of the city, sanitary and storm sewers are separated, with street runoff piped directly back into the city's waterways—Rock Creek and the Potomac and Anacostia rivers. In the case of heavy rains, the separated system is much better; combined sewers can't handle all the street runoff during rainstorms, leading to the dumping of raw sewage into waterways—as much as 2.5 billion gallons of mixed effluent in an average year. But in the case of a light rainfall or snow, the combined sewers are much more green, since all the runoff gets treated.
Unfortunately, the thousands of tons of snow hauled off by the city are being deposited on a parking lot at D.C. General Hospital, just barely outside of the part of the city that has combined sewers—meaning the melt will end up in the Anacostia.
Asked if there's a way to store snow in a place where it might melt into sewers that head to Blue Plains, Hawkins says that "it's been an issue that's been raised." But finding a suitable location to dump snow in the combined-sewer zone—the most heavily developed part of the city—is a challenge, he says.
Perhaps there is a solution: WASA engineers have informed Hawkins that "way back in the old days" the city set up "chutes" downtown to dump snowfall directly into the combined sewer system. But that method fell out of favor when the city starting using sand to maintain traction on city streets—the sand fouls the sewers. But these says, Hawkins says, DPW uses much less sand, so the chutes might be a viable option in the upcoming snowmageddons.