New & Redevelopment Stormwater Management

As of May 16, 2022, all new and redevelopment construction projects, both private and public, must comply with the 2021 King County Surface Water Design Manual.

2021 King County Surface Water Design Manual

Burien's surface water features (lakes, wetlands, streams, and Puget Sound) are a significant part of our natural beauty and rich heritage. Spawning salmon, meandering streams, and clean water are important natural resources that must be managed wisely to protect their value. With this in mind, the City of Burien has taken steps to preserve and restore the natural environment through managing the stormwater runoff created by new and redevelopment projects within the City.

Through the end of 2016, the City required construction projects to meet standards set in the 2009 King County Surface Water Design Manual. In order to comply with the City’s current NPDES Stormwater Permit from the Washington Department of Ecology, the City adopted the updated 2016 King County Surface Water Design Manual, which became effective for all new development and redevelopment projects submitting applications beginning January 1, 2017. This Surface Water Design Manual contains the requirements and standards for designing stormwater management systems in the City of Burien. As part of the permit approval process for certain types of permits for proposed projects, Burien requires the construction of surface water and stormwater management systems to mitigate the impacts on natural and existing man-made drainage systems.

Changes from 2016 Manual

The most significant change to the new King County manual is the addition of Low Impact Development (LID) BMPs (called Flow Control BMPs in the manual), which will be required for nearly all development projects within the City. These BMPs include facilities such as bioretention (rain gardens), permeable pavements, dispersion, and onsite infiltration.

As described in the 2021 King County Surface Water Design Manual, existing site conditions shall be considered historic site conditions. Historic site conditions are those that existed on the site prior to any development in the Puget Sound region (ref. BMC. 13.10.140). Historic site conditions shall be assumed to be forest cover.

Summary of Changes from the 2016 manual

For current and past projects still utilizing the 2016 King County Surface Water Design Manual, information regarding the 2016 manual is available here: 2016 King County Surface Water Design Manual.

More information

Please direct your comments or questions to Heungkook Lim at (206) 248-5516, or [email protected].

Updated September 29, 2022