Curtis Hinman, WSU Puyallup Research and Extension Center, on “Flow Control and Water Quality Treatment Performance of a Residential Low Impact Development Pilot Project in Western Washington”:

LID will become the first approach to dealing with water quality issues.

Pilot Project: Meadow on the Hylebos (35 home community): partnership between local government (Pierce County), designer, owners, and developer

Goals: mimic native hydrologic function (for Hylebos Creek) and provide “an affordable and livable neighborhood” 

Monitoring Objectives:  how well the project matches flood-control standards, effectiveness of LID techniques, stormwater runoff quality, and provide accurate scientific data

LID features (‘LID light’): bioretention swales along roads, pervious concrete, compost amended soils and sloped biodentention

For 0.3 ha sub-basin, project exceeded design objectives and met forested duration standard.  Also exceeded objectives at Hybelos Creek.  Water quality results from 2 storms:  metals were below detection threshold.

If largest planned bioretention area was functional, modeling shows this would have met forested duration standard at Point of Compliance.

“The LID applications appear to be robust.”