BIORETENTION — “RAIN GARDENS”
“Bioretention” is a broad term. “Rain garden” is still broader. Indexed here are projects with relatively small depressed areas designed to retain water for a short time in order to slow down and reduce storm runoff peaks, as well as reduce pollution. A common slogan is “slow it, spread it, sink it.”
Keeping a runoff pattern reasonably similar to what existed before development generally requires some 3-5% of the project area, as well as excavation and plumbing: Raised drains to prevent flooding, underdrains to carry heavy flows to storm drains, and layers of crushed rock and highly permeable soil.
Not indexed here are (a) larger ponds or (b) projects with bioretention areas that are a relatively small part of a more complex system. Large parking areas, for example, often have both elongated swales and small corner bioretention areas.
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Alameda County Juvenile Justice Center
Albany School District’s Cougar Field
Penney’s, Antioch; Lowes, Concord
El Cerrito Sidewalk Rain Gardens
El Cerrito City Hall
Emeryville: Doyle-Hollis Park
Martinez: Slowing runoff on a slope
Oakley City Hall
Pittsburg City Hall and Richard E. Arnason Justice Center
Pleasant Hill: Hidden Creek
San Pablo: Shopping area at El Portal Drive and San Pablo Avenue
UC Berkeley: Grinnell Glade
Walnut Creek: AAA and Varian Headquarters
Walnut Creek Downtown Public Library