Chicago has been making interesting strides in its efforts to move toward sustainability. I've noticed recently that the city is starting to compete with green players like Boston, San Francisco, and Vancouver for sustainability news headlines. In this edition, Chicago is repaving its alleys with permeable pavement, allowing water to filter back to Lake Michigan.

Chicago claims 13,000 alleys, amounting to more than 3,000 acres and nearly 200 miles of poorly drained pavement. Many of Chicago’s alleys -- built ahead of the city’s sewer system -- lack basic drainage; when it rains the alleys routinely flood basements and sometimes present problems for ground-floor tenants.

The city's sewer system is already maxed to capacity and the alley issue presented a need for new solutions, such as permeable pavement. Now Chicago’s alleys will be paved with a light colored substrate that is both permeable and heat resistant and peppered with microbes that consume pollution. Once the new surface is in place, Chicago’s alleys will  act like filters, recycling water more safely, efficiently and environmentally back into the aquifer and eventually into Lake Michigan.