Chicagos Green Alley Guide
Starting with a problem flooded basements and storm sewers filling to capacity the City of Chicago responded with the application of sustainable design principles to the humble alleyway, in order to both prevent problems and to deliver a number of financial, environmental and social benefits:
- Preventing basement flooding
- Recharging groundwater supplies with stormwater runoff from alleys
- Naturally degrading [[ ?? "infiltrating"?]] alley stormwater pollutants in [[into?]] the ground
- Reducing summertime temperatures and ozone in neighborhoods
- Extending the life of alley paving
- Creating a more beautiful alley with improved habitat for birds and wildlife
- Saving energy and preventing glare with dark sky compliant alley lighting
- Promoting citizen recycling and composting of solid waste
The Chicago Green Alley Handbook presents numerous sketches of best practices any city can use when rebuilding alleys or building new alleys, along with best practices citizens can adopt to make their blocks more sustainable. The key practice is, where soil conditions are appropriate, to allow water to infiltrate into the soils through permeable pavement (concrete or asphalt or pavers), infiltration trenches under the alley, or rain gardens and bioswales alongside the alley, instead of directing water into the sewer system or onto adjacent property. Other practices include:
- Use of light-colored, recycled-content materials in paving surfaces
- Installation of water-absorbing, temperature-cooling, beautiful green roofs on garages and flat-roofed apartment buildings
- Growing shade trees and native plants
- Use of rain barrels and cisterns
Chicago has completed 46 green alleys. The higher cost of construction is offset by what the City would have paid for maintenance and sewer improvements for the old ones. Adding in the additional benefits of green alleys has convinced the City that every alley it refurbishes in the future will be a green alley.
For more info, read the Worldwatch Institutes story about Chicagos efforts.