Low Impact Development (LID) Design for New and Re-Development: The New Normal for Site Design

By Bill Taylor

With the release of the new 2013 NPDES Municipal Stormwater Permit, local jurisdictions must put into place minimum requirements for controlling runoff from new and re-development, and from construction sites. These requirements are prescribed in the new 2012 Stormwater Management Manual for Western Washington (SWMMWW) – or equivalent standards – and rely heavily on promoting Low Impact Development (LID) as “the preferred and commonly used approach for site development.” With the inclusion of the SWMMWW into local jurisdictions development codes, stormwater management using LID is a new and expected standard in our region’s land use development.

LID emphasizes minimizing native vegetation and soil loss and reduction of impervious surface. Once these impacts are reduced, the focus is on promoting infiltration of stormwater runoff through on-site bioretention and pervious hard surfaces (e.g. porous concrete or asphalt). Stormwater reduction through site building layout is also encouraged through reduced building clearances and pedestrian circulation rather than road networks.

While the design standards for this rapidly developing discipline of LID can appear complex, expected reduced costs can include additional useable space, reduced clearing and grading quantities, and elimination or reduction of traditional hard infrastructure for stormwater control. In addition, local jurisdictions’ development review staff are increasingly experienced in facilitating design review and recommendations to support the inclusion of LID in development design.

Nonetheless, the overall process of planning and implementing LID design in site development will call for new guiding visions, creativity, and development team organization. Raedeke Associates is developing these capabilities together with our natural resources management and landscape architecture services to help you develop ways to apply LID concepts as part of an integrated site design.