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Low Impact Development Greens Facilities to Reduce Risk and Water Contamination
Low Impact Development Reduces Stormwater and Urban RunoffHistorically, America's community motto for stormwater management has been "conveyance" -- moving water away from the site where it falls as quickly as possible. Traditional stormwater management tools include street gutters and curbs, pipes, and canals to remove water from the developed areas by reshaping creeks and rivers and lining them with concrete. And detention ponds, some with water quality filtration devices, regulate discharge to reduce peak flow impacts on receiving waters. For the most part, these practices reduce flood impacts, but do not completely address water quality, and aquatic and riparian habitat degradation issues.Low Impact Development Reduces Cost with Source Control and InfiltrationIn contrast with these long-practiced, expensive approaches, the guiding principle of low impact development approaches is not conveyance; it is "source control and infiltration". LID techniques maximize the area available for absorbing water into prepared soil through infiltration so that runoff volume and pollutant concentrations are reduced. Low impact development is achieved through a variety of site design and engineered infiltration techniques.Benefits of Low Impact Development that Save Money and EnvironmentSome of the benefits of low impact development include:
Retrofit a Parking Lot to Increase Permeability.Over sixty-five percent of impervious areas are associated with "habitat for cars". Using porous pavement in parking lots is a simple way to provide infiltration and reduce runoff.Adding bioretention cells to landscaped areas and disconnecting downspouts can reduce peak runoff without losing parking space. Re-design of parking and driving space can reduce runoff without decreasing the amount of parking spots -- and reduced peak runoff and pollution protects and helps restore our streams, rivers, lakes and the ocean...the ultimate catche basin for all our urban runoff stormwater and pollutants. Retrofit Streets to Reduce Runoff..and Increase ShadeBuilding vegetated swales, bioretention cells, and narrower streets without curbs promote effective drainage and filtration systems that use natural filtration by soil to keep pollutants, fertilizers, and other chemicals out of our precious fresh ground water system.The basic components of a bioretention cell, or rain garden, are water flow from impervious areas; a filter strip that allows infiltration; a detention and filtration zone to hold rapid runoff, amended soil for hardy, native vegetation, and a buried under-drain discharge pipe for excess water. These beautifully disguised water systems provide natural water storage, filtration and watershed flow of rains. Local watershed systems not only are natural storage for our fresh water supplies, but they are the nurseries for local wildlife such as fish, frogs, dragonflies, and even mammals. After all, what life doesn't need fresh, potable water for drinking and bathing? Replace lawns with rain gardens.Rain gardens are small bioretention cells landscaped with plants, trees, and grasses. They are a particularly good way for small lot owners to enhance their landscaping while protecting water quality. By planting easy-care native wildflowers, hardy perennials and grasses, attractive gardens can be landscaped that have added environmental benefits.More information on rain gardens is available at: Rain Gardens.
You can find more information about bioretention cells and stormwater management using rain gardens,etc. at the following resources:
There are challenges with low impact development, such as cost and maintenance, but the economic benefits offset these with environmental integrity: reduced cost of stormwater infrastructure, reduced utility fees, increased land value and decreased spending on some other environmental conservation programs. The natural way is pretty good -- and low impact is always a cost saver in the long run!
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