De-Paving and Improving Urban Permeability

Removing pavement, it turns out, is not enough to get rainwater to soak back into the ground. After years of being compacted and covered by asphalt, recently sunlighted grounds are far more effective at absorbing rainwater after a good tilling.

"[T]o make that urban hardpan act more like a natural sponge and cut down on storm-water pollution, city officials are trying out the agricultural process known as 'sub-soiling.'

At Yorkwood Elementary School in Northeast Baltimore this week, a tractor plowed deep into a half-acre patch of playground that until recently had been covered in asphalt. The farm vehicle towed a claw-like contraption with long curved blades that slice far into the packed earth."