UD-01 · 03 Urban Design
Sponge streets
A street that is asked to drink: rain gardens, permeable paving and a curb that lets water into soil instead of a pipe.
Origin
Sponge-city practice in China; water-sensitive urban design
Materials
- A survey of the block's high and low points
- Curb cuts, rain gardens and a soil mix that drains
- Deep-rooted perennials and trees that tolerate wet feet
Method
- 01
Walk the street in a storm. Mark every place water already wants to go. Design follows that map, not a catalogue of planters.
- 02
Cut the curb where flow concentrates and drop a planted basin deep enough to hold a design storm, with an overflow to the next basin, not to a neighbor's door.
- 03
Use a soil that is sandy enough to drain and organic enough to live. A sealed planter is a bathtub.
- 04
Plant for roots, not for a ribbon-cutting. Trees and rushes do the hydrology; annual flowers do not.
- 05
Agree who weeds and who unclogs the overflow. A sponge street that is not tended becomes a mosquito trench.
What this makes possible
- Less flooding at the bottom of the block
- Cooler air along a planted curb
- A public landscape that is also a piece of infrastructure
This is a field record, not a permit. Adapt to local law, climate and skill. If you have run this method, send what you learned.