National Geographic article by Paul McRandle about Philadelphia’s Green City Clean Waters stormwater management program.
(2012) National Geographic article by Paul McRandle. The Green City Clean Waters program requires that green infrastructure be capable of keeping one inch of rainwater out of the storm-water system in a 24-hour period. The city developed permeable paving in the 1970s that allows water to infiltrate while still providing a hard surface for vehicles. Green City Clean Waters calls for square miles of impervious surfaces to be replaces with permeable pavement. The city is also looking at other green infrastructure hard features like determining which tree well systems perform best.