Low impact development

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Low Impact Development - using vegetation and structural BMPs to mimic the pre-existing hydrologic conditions

Low Impact Development (LID) is a term used in the United States to describe a land planning and engineering design approach to managing stormwater runoff. LID emphasizes conservation and use of on-site natural features to protect water quality. This approach implements engineered small-scale hydrologic controls to replicate the pre-development hydrologic regime of watersheds through infiltrating, filtering, storing, evaporating, and detaining runoff close to its source.^[1]

LID is similar to Sustainable urban drainage systems (SUDS), a term used in the United Kingdom.

1 Alternative to Conventional Stormwater Management Practices
2 Typical LID Practices and Controls
3 Benefits of LID
4 See also
5 References
6 External links

[edit] Alternative to Conventional Stormwater Management Practices

A concept that began in Prince George's County, Maryland in 1990, LID began as an alternative to traditional stormwater best management practices (BMPs) installed at construction projects.^[2] Officials found that the traditional practices such as detention ponds and retention basins were not cost-effective and the results did not meet water quality goals.

The LID design approach has received support from the U.S. Environmental Protection Agency (EPA) and is being promoted as a method to help meet goals of the Clean Water Act.^[3] Various local, state, and federal agency programs have used materials supplied by the LID Center (a non-profit group dedicated to advancing the practice). LID techniques can also play an important role in Smart Growth and Green Infrastructure land use planning.

[edit] Typical LID Practices and Controls

Planning practices include several related approaches that were developed independently by various practitioners. These differently-named approaches include similar concepts and share similar goals in protecting water quality.

Conservation design, also called Conservation Development
Better Site Design
Green Infrastructure.

Planners select structural LID practices for an individual site in consideration of the site's land use, hydrology, soil type, climate and rainfall patterns. There are many variations on these LID practices, and some practices may not be suitable for a given site. Many are practical for retrofit or site renovation projects, as well as for new construction. Frequently-used practices include:

Bioretention cells, also known as rain gardens
Cisterns and rain barrels
Green roofs
Permeable paving, also called "porous pavement"
Grassed swales, also known as bioswales.^[4]

[edit] Benefits of LID

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Habitat protection
Improved management of water quantity (e.g. reduced risk of flooding)
Reduction of impervious surfaces and runoff (peak flow volume and rate)
Groundwater recharge through infiltration
Water quality improvements
Community value (i.e. increased aesthetics)
Cost savings.^{[citation needed]}

[edit] See also

[edit] References

^ Prince George's County, Maryand. Department of Environmental Resources. Larry Coffman et al. Low-Impact Development Design Strategies, An Integrated Design Approach.Published by U.S. Environmental Protection Agency, Washington, D.C. Document No. EPA 841-B-00-003, June 1999.
^ Prince George's County, Maryland. Department of Environmental Resources. 1997. Landover, MD. Low Impact Development Design Manual.
^ U.S. Environmental Protection Agency. Washington, D.C. Low Impact Development (LID): A Literature Review. October 2000. Document No. EPA-841-B-00-005.
^ U.S. Environmental Protection Agency. Washington, DC. "Fact Sheet: Low Impact Development and Other Green Design Strategies." June 1, 2006.