Monday, May 23, 2011

Terrace rain gardens catch sidewalk runoff


On May 11, a hailstorm knocked maple flowers onto the pavement.  Rivulets traced patterns in the yellow flowers, showing where the runoff goes.  It's clear that most sidewalk runoff flows into the street, where it's flushed quickly by sewers to the lakes.

In my neighborhood--built in the 1950s--the turf bulges above the sidewalk.  So runoff is channeled along the sidewalk until the next driveway, where if usually escapes to the street.

In some level areas, the water just puddles on the sidewalk.  In the winter, these puddles can freeze, creating a hazard.  In the photo above, you can see where puddles are forming on the left.

If you dig out the turf next to the puddles, you can create a lovely rain garden--one that also drains the puddles.  The garden will be lush, because it gets an extra dose of water.

This long slope channels a lot of runoff to the street.

This driveway channels runoff from the downspout to the street.
Rain gardens on the terrace, on either side of the drive, would catch runoff from the sidewalk, drive, and roof.

Terrace rain garden in action--taking water from the sidewalk.

The bottom line

Rain gardens on the terrace can help replenish groundwater, beautify neighborhoods, and eliminate annoying sidewalk puddles.

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