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EPA's Region 8 Green Roof
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| Green Roof Vegetation Growing Over Drip Irrigation |
Regional Information |
The primary objective of EPA's green roof is to absorb the precipitation which contacts the roof surfaces and release it at a reduced and measured pace. The green roof is expected to reduce peak flow and runoff volumes from rain and snowmelt events to mimic a more natural landscape. Reducing the peak flow will minimize deleterious impacts to the South Platte River from concentrated stormwater runoff.
Natural landscapes like forests, wetlands, and grasslands trap rainwater and snowmelt and allow them to filter into the ground slowly. In contrast, impervious surfaces like roads, parking lots, and rooftops prevent rain and snowmelt from infiltrating, or soaking, into the ground. In an urban environment with mostly impervious surfaces, rain and snowmelt remains above the surface, where it runs off rapidly in unnaturally large amounts.
Storm sewer systems concentrate runoff into smooth, straight conduits. This runoff gathers speed and erosive power as it travels underground. When this runoff leaves the storm drains and empties into a stream, its excessive volume and power erode streambanks and streambeds, damaging streamside vegetation and dramatically altering aquatic habitat. These increased storm flows carry sediment loads from construction sites and other denuded surfaces and eroded streambanks. They often carry higher water temperatures from streets, roof tops, and parking lots, which are harmful to the health and reproduction of aquatic life.
