The city of Chicago has announced plans to green its 2,000 miles of alleyways by installing permeable ground coverings that will allow rainwater to seep back into the ground and replenish groundwater supplies.
"With nearly 2,000 miles of small service streets bisecting blocks from the North Side to the South Side, Chicago is the alley capital of America. In its alleys, city officials say, it has the paved equivalent of five midsize airports."
"Chicago has decided to retrofit its alleys with environmentally sustainable road-building materials under its Green Alley initiative, something experts say is among the most ambitious public street makeover plans in the country. In a larger sense, the city is rethinking the way it paves things."
"In a green alley, water is allowed to penetrate the soil through the pavement itself, which consists of the relatively new but little-used technology of permeable concrete or porous asphalt. Then the water, filtered through stone beds under the permeable surface layer, recharges the underground water table instead of ending up as polluted runoff in rivers and streams."
"Some of that water may even end up back in Lake Michigan, from which Chicago takes a billion gallons a year."