If you live in Chicago, the alley behind your building is part of the largest public alley system in the world.
And, soon, it may be part of the greenest alley system in the world.
Although alleys are designed higher on the sides than in the center (so that water flows to the street and then into catch basins), over time, they lose their grade. Water can pool up during storms and then run into yards and basements. Alleys also absorb heat and increase city temperatures.
To address these issues, about four years, the Chicago Department of Transportation explored the possibility of transforming the city’s 1,900 miles of public alleys into permeable alleys.
The “Green Alley Program” emerged and, using permeable asphalt and concrete, the city has succeeded in laying alleys that reflect heat and allow water to flow into the ground.
So far, 40 green alleys have been laid. And, this week, the Chicago Sun-Times announced that the program earned the city a 2007 Chicago Innovation Award.
The permeable asphalt recycles tire rubber in its mix and the concrete uses a byproduct of metal processing to make it reflective.
