King County Road Services - Low Impact Development (LID) for Roads - Military Road S. at S. 272nd St. Project - Bioretention facility/rain garden

What is a bioretention facilty?

A bioretention facility, also known as a rain garden, is a vegetated closed depression that retains and filters stormwater runoff from an area of impervious surface such as pavement. This project will be constructing a vegetated bioretention facility. It will be used primarily for water quality treatment, but the amended soil layer, which acts as a sponge holding water, will also provide some flow control.

Example design of a bioretention facility

Drawing of the bioretention facility for this project

Related documents

• King County Surface Water Design Manual 2005, Appendix C, Rain Garden Section (393KB .pdf)
• LID Technical Guidance Manual for Puget Sound, Rain Gardens Section (384KB .pdf)

Related Web sites of interest

• Wikipedia - Definition of "Rain garden"

• King County
  
  • Surface Water Design Manual
  • Surface Water Design Manual, Appendix C, Small Project Drainage Requirements, pg. C-56 (9MB .pdf)

• Puget Sound Action Team
  • LID Technical Guidance Manual
    
    • Pg. 65
    • Design criteria pg. 151

• Washington Department of Ecology
  • Stormwater Management Manual for Western Washington (revised 2005)
  • Appendix III-C, pg. C-13

• EPA
  • Stormwater Terminology Fact Sheet
  • Low-Impact Development Design Strategies: An Integrated Design Approach, pg. 4/8

• Federal Highway Administration
  • Stormwater Best Management Practices in an Ultra-Urban Setting: Bioretention Fact Sheet