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® • According to a 1992 Inventory by the U.S. Environ- Stormwater systems can be designed as an ame- • Opportunities to reveal the natural terracing to mental Protection Agency, more than one-third nity, a multiple use civic Infrastructure that makes the Minnesota River and to reconnect people of American rivers and nearly one-half of Its lakes water processes legible,sustainable,and expressive. experientially to the Minnesota River Valley. are unfit for drinking,swimming or fishing,Non-point If stormwater Is perceived as a replenishing amenity . Opportunities for practicing responsible regional source pollutants such as pesticides, fertilizers, and resource, rather than a waste that should be watershed planning at the site scale. heavy metals, urban sediments, dumpster hidden away, stormwater systems can Incorporate g leachate, oils and detergents pose the greatest earth and vegetation to serve as cleansing filters. • Opportunities to create public gathering spaces threat to water quality. Burnsville's adjacency to at larger water collection areas which celebrate the Minnesota River necessitates a responsibility to Several innovative technologies have been devel- the ephemeral qualities of a rainstorm or spring protect water quality. The Heart of the City rede- oped to ameliorate poor stormwater quality. Using thaw. velopment project affords a unique opportunity these strategies to daylight stormwater processes • Opportunities to create a common vocabu- to address this Issue in an Integrated and Innova- benefits overall water quality by: lary of streetscape elements rooted In place tive way. through the use of native plants and the rev- Lowering peak flow velocity and volume. elation of ephemeral climatic events. Nineteenth century perceptions of water as a Lessening possibilities of erosion. carrier of filth and disease are still prevalent in cur- A. DETENTION PONDS OR rent stormwater design.Stormwater traditionally has Settling heavy metals and silt out of stormwater been regarded as a waste to be disposed of as flow. MARSHES efficiently and Invisibly as possible.This requires large Filtering pollutants,silt,phosphorous and nitrogen. amounts of Impervious surface replete with curb Regenerating groundwater. Detention ponds and marshes detain and store and gutters and elaborate subterranean pipe Cooling water before it reaches a water body, stormwater runoff to allow for settling of particulate matrices,which,Ironically,contribute to lower wa- Reusing ater for irrigating pollutants,vegetative uptake,and control of peak ter qualify In rivers and groundwater due to: g g g parks and gardens flood rates. They may be constructed above or • Increased I rather than installing expensive systems. below grade, be wet or dry. Although these sys- • Thermal polllutiluti on n Ameliorating the heat Island effect of urban ar- tems control peak rates, they do not mitigate in- • Heavier pollutant nitrogen and phosphorous eas. creased runoff volumes. loading Other benefits Include: • Increased erosion 0 Enhancing the amenity value of the commu- nity. In vegetated areas possessing little Impervious sur- a Supporting biodiverstly at the street level by build- face, a minimal amount of water drains Into wa- ing ecological structure. terways In the first few hours during and after a 0 Lowering capital costs for municipal Infrastruc- storm event. Most of It Is either absorbed by veg- ture. etation or the ground and takes days to months to reach the river. In contrast, a large amount of Educating the community about drainage and Impervious surfaces speeds up the process: cleansing processes of degraded water. stormwater can reach the river in a matter of min- Opportunities to Incorporate art and education utes. with the use of follies celebrating the hydrologic event.