Green Infrastructure Strategies for Rainwater Management.

Let It Rain

Green roofs at Vancouver's South East False Creek retain and use rainwater, while the excess is caught in basement cisterns. The water is used for landscaping, flushing, or circulates through neighborhood water features. Site water makes its way to either an on-site bioswale or False Creek. Image courtesy The Challenge Series 2009

January 2011 - Perhaps my most vivid memory of architecture school comes from a studio in which we built a model of a neighborhood design, and then poured water all over it. The trick was to use enough little pieces of sponge in the model, representing rainwater retention strategies at a variety of scales, so that no water spilled onto the floor. Across North America, regions and municipalities are now trying this trick for real. Why? Because the centuries-old approach of piping water off the land as fast as possible and dumping it into waterways is failing fast.

Each year in Philadelphia, a city with some of the oldest combined storm and sewer infrastructure in North America, billions of gallons of sewage over-flow from 164 outfalls into the city’s creeks, streams, and rivers during major rainstorms. In Milwaukee, a hospital study shows the number of children with serious diarrhea rising whenever the city’s sewers overflow. Run-off pollution from suburban and agricultural sources threatens New York City’s drinking water supply. And it’s estimated that every twenty-four months, rainwater run-off from the streets of Seattle flushes into Puget Sound a volume of oil equivalent to the Exxon Valdez spill. {continued}