Low impact development is a planning and design approach that manages runoff near where it falls using site-scale practices.
Definition
Low impact development, often shortened to LID, is an approach to planning and site design that seeks to manage rainfall close to where it lands. Project practices may include preserving open space, limiting impervious area, infiltration, or vegetated stormwater features. The particular definition and required practices depend on the jurisdiction, client, and project criteria. A firm may evaluate soils, groundwater, grading, utilities, and maintenance needs before including LID features in a design. Different firms may use the term for different combinations of practices, so the scope should name the proposed measures and intended outcomes. LID is not a single facility or a promise that runoff will be eliminated. Its effectiveness depends on site conditions, design, construction, and upkeep. The approach may work alongside conventional drainage systems where project needs call for both.
How owners use it
- Consider site layout options that manage rainfall near its source.
- If a site reduces impervious area from 6 acres to 4 acres, the reduction is 6 - 4 = 2 acres.
- Coordinate infiltration or vegetated practices with grading, utilities, and maintenance planning.
- State the particular practices and criteria included when a proposal uses the LID label.
