Low Impact Development (LID), often referred to as Conservation Development, combines a number of design, pollution prevention and treatment Best Management Practices (BMPs) to minimize the amount of untreated storm water runoff leaving a site. More than a treatment, LID is a design strategy to match the pre-development and post-development storm water runoff conditions as closely as possible. Innovative planning can result in a site yielding the same number of houses or buildings but with significantly less impervious area. What results is an area with increased infiltration and decreased storm water runoff.
Conservation design or LID design employs concepts like clustering, where buildings are situated closer to one another, which leaves for greater common green space. The design still yields the same number of structures and lots yet they are designed to maximize protection of the stream and maintain areas that provide important natural functions.
BMPs like vegetated filter strips, porous pavement, bioretention areas and vegetated rooftops are often included in an LID design. Rather than utilizing just one BMP, LID employs multiple BMPs to achieve the most substantial water quality benefit.
Some additional benefits of LID include reduced land clearing and grading costs, a potential reduction in infrastructure costs, increased lot and community marketability and a reduction in impacts to local terrestrial and aquatic ecosystems. Savings on infrastructure can be illustrated in a reduction in street lengths, sidewalks and lengths of sewers.
In short, LID allows for the full development of the property with reduced associated costs. While Low Impact Development concepts are still rather new, they provide an effective alternative to those wishing to explore the connection between development and environmentally-conscious design.
Additional information regarding Low Impact Development can be obtained from the following suggested resources:
Low Impact Development Center
http://www.lowimpactdevelopment.org/
Center for Watershed Protection
http://www.cwp.org/
Low Impact Development Urban Design Tools
http://www.lid-stormwater.net/
U.S. EPA Low Impact Development Page
www.epa.gov/owow/nps/lid/
U.S. EPA Green Streets Guide (PDF, 5.7 MB)
www.epa.gov/npdes/pubs/gi_arra_green_streets.pdf
Land Choices
http://www.landchoices.org/
Puget Sound Action Team
www.psat.wa.gov/Programs/LID.htm
Minnesota Land Trusts (includes case studies)
www.mnland.org/prog-consplanning.html