You may have noticed green infrastructure appearing in neighborhoods around D.C. lately — rain gardens next to the sidewalk, permeable pavers in alleys and parking lanes.
These projects are designed to absorb stormwater so the rain doesn’t fill up the city’s antiquated sewers and cause them to overflow into the Anacostia, Potomac or Rock Creek. But green infrastructure is too expensive in a densely built-up city like D.C. to be used on a large scale, according to a new assessment by DC Water.
The water and sewer authority now plans to scale back its green infrastructure projects in the Rock Creek watershed, and instead build a 4.2 million-gallon concrete tunnel — “grey infrastructure” — to capture stormwater until it can be treated.
“When we projected what a 30-year cost would look like, green infrastructure was almost twice as expensive as grey infrastructure,” says DC Water spokesman Vince Morris.