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demonstration rainwater garden system

demonstration rainwater garden system
City of Burnsville

gardens successfully decrease stormwater runoff

To protect Crystal Lake from excess phosphorus and large volumes of stormwater, the Metropolitan Council and the City of Burnsville funded a prototype rainwater garden system in a nearby residential area to catch runoff from streets and driveways.

Retrofit of the 1980s neighborhood involved individual designs for each participant’s property and close attention to education and maintenance. The shallow depressions feature gradual side slopes, limestone retaining walls, and colorful plantings. Deep-rooted vegetation was planted to facilitate infiltration, filter pollutants, and create bird and butterfly habitat.

To assess the system’s effectiveness, Barr helped city staff compare the neighborhood with the 17 new rainwater gardens to a similar residential area without them, which served as a control site. Data collected for two seasons before and two after the gardens were installed determined that the rainwater gardens reduce runoff volumes by approximately 90 percent.