West North points out that instead of spending $8 billion to build new sewage holding tanks throughout the city, the Philadelphia Water Department plans to conver impervious surfaces to pervious, natural surfaces. The American Society of Landscape Architects has more information on The Dirt:
The green infrastructure proposal would turn 1/3 of the cityâ€™s impervious asphaltÂ surface, or 4,000 acres,Â into absorptive green spaces. The goal is to move from grey to green infrastructure. Grey infrastructure includes â€œman-made single purpose systems.â€ Green infrastructure is defined as â€œman-made structures that mimic natural systems.â€ As an example, networks of man-made wetlands, restored flood plains, or infiltration basins would all qualify as green infrastructure. The benefits of such systems include: evaporation, transpiration, enhanced water quality, reduced erosion / sedimentation, and restoration. Some grey / green infrastructure feature integrated systems that create hybrid detention ponds or holding tanks, which are designed to slow waterâ€™s release into stormwater management systems.
And, like Portland, Philadelphia is accomplishing more than just better stormwater management.
…the city is calling for a triple-bottom line approach, aiming for: more green spaces, improved public health, and more greenÂ jobs. [The Dirt]
Portland is building “Green Streets” that combine bicycle facilities with green infrastructure like bioswales inside curb extensions. This plan did not arise perhaps as altruistically as Philly’s (actually with a little controversy), but more as a way to build bicycle facilities with bioswale funding.