Surface Water Management
Snohomish County Drainage Manual
Revised Drainage Manual Adopted Sept. 2010
Snohomish County Department of Public Works (DPW) has adopted a revised Drainage Manual. The Drainage Manual, adopted by rule in accordance with Chapter 30.82 SCC, is effective on September 30, 2010. The current version of the Drainage Manual applies to any development or redevelopment projects vested after September 30, 2010. The current Drainage Manual also applies to pollution-generating activities at sites with existing development. The past edition of the Drainage Manual is posted at the bottom of this page, for use with projects vested to it.
Current Drainage Manual (effective Sept. 30, 2010) |
The documents listed below compose the entire Snohomish County Drainage Manual. The Drainage Manual is used in concert with Snohomish County code and Snohomish County Engineering Design and Development Standards.
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Past Edition of Drainage Manual (prior to Sept. 30, 2010) |
Drainage Manual Intro (pdf)
Volume I - Minimum Technical Requirements
Volume I of the 1992 Ecology Stormwater Management Manual for the Puget Sound Basin was adopted by Snohomish County in 1998. The 1998 Snohomish County addendum applies to this Volume.
Volume II - Construction Stormwater Pollution Prevention
Volume II of the 2005 Ecology Stormwater Management Manual for Western Washington was adopted by Snohomish County in 2005. The 1998 Snohomish County addendum does not apply to this Volume.
Volume III - Runoff Control
Volume III of the 1992 Ecology Stormwater Management Manual for the Puget Sound Basin was adopted by Snohomish County in 1998. The 1998 Snohomish County addendum (see above) and the 2008 amendment related to facility maintenance (see below) apply to this Volume.
2008 Snohomish County Drainage Manual Volume IV
This document was written by Snohomish County and adopted in 2008 to replace previous Volume IV. The 1998 Snohomish County addendum does not apply to this Volume.
2009 Snohomish County Drainage Manual Volume V
This volume contains only a reference to the drainage maintenance standards in Volume III Chapter III-9. When the Drainage Manual is fully revised in 2010, maintenance standards and other information will be moved to Volume V.
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DPW Project Administration Rule Adopted (Sept. 30, 2010) |
In accordance with the recently-revised land disturbing activity code (Chapter 30.63B SCC), DPW has also adopted a rule setting forth procedures DPW will follow to ensure compliance with the land disturbing activity code, drainage code (Chapter 30.63A SCC), and low impact development code (Chapter 30.63C SCC).
Comparison of 2010 Snohomish County Drainage Manual to
2005 Ecology Stormwater Manual |
The 2010 Snohomish County Drainage Manual is a significantly revised version of the 2005 Ecology Stormwater Manual. The document in the link below describes the specific changes made to the 2005 Ecology Stormwater Manual, and also describes the general rationale used by Snohomish County in making the specific changes.
Contact
Please address any questions to: Bill Leif, (425) 388-3148
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