Stormwater Chain, Capturing Stormwater Run-Off (Final in a Series)

Landscape, Street and Parking Swales

It has been stated and proven the need to create greater environmental awareness in dealing with water conservation is evident. Bringing awareness and understanding will create the means to implement some of these simple principles.  Landscape, street and parking lot swales are threads in the stormwater chain and part of these simple and responsible principles.

Landscape swales temporarily store run-off water while reducing pollutants with its vegetation from small to moderate rain events.  These swales are usually low depressions designed to collect, reduce flow, and move stormwater run-off with its greatest attribute of allowing water to infiltrate into the ground, re-charging ground water while cleaning the water of its pollutants.

These swales, as recommended by The Portland Manual are average 6” deep by 2’ in width in private and commercial use, and a maximum of 4’ wide for public swales.  This is one of the main differences between a swale and a bio-retention pond that may include a forebay area to encourage sedimentation and substantially deeper to accommodate greater amounts of water run-off.

Street swales provide tremendous benefits to residential neighborhoods, not only for reducing run-off and flow rates, but also for integration within streets to slow down traffic by narrowing the street and essentially creating green streets.  These street swales are small scale features designed to take run-off from the street.

Typical parking lots have been designed with raised or curbed greenspaces dividing parking rows.  To take advantage of collecting stormwater, they are now being properly designed with depressed sunken greenspaces that are vegetated within these large scale non-pervious parking areas.  Again, the vegetation is essential to filtering contaminants that may be within the run-off water.  Landscape architects & designers are now looking at ways to actively and aesthetically install these swales alongside domestic driveways and parking areas near gardens and residential yards to continually expand the possibilities of capturing stormwater.