Single Family Residence Stormwater Requirements

The 2014 Stormwater Management Manual for Western Washington was adopted by the City as of January 1, 2017. New and re-development projects must follow new design requirements which are now often triggered with just a Single Family Residence project. The City is currently developing a toolkit for developers to navigate the new requirements, and help compile submittal materials and documents.

In the interim, read through the information below for a general overview of the new requirements.

Stormwater Submittal Requirements

Prior to building permit submittal, you will have to determine what minimum requirements for stormwater management are required to be address with this development/design, based on the State mandated guidelines described in the 2014  Stormwater Management Manual for Western Washington (SMMWW). The flow charts that walk you through which minimum requirements that you will have to address are located in Volume I of the SMMWW, section 2.4.

If you trigger minimum requirements #1 through 5 or #1 through 9, a Civil Engineer must be utilized to address the required minimum requirements with the building permit submittal. Please review the step by step analysis mentioned in Chapter 3 –Preparation of Stormwater Site Plans that is located in Volume I of the SMMWW for what we will expect to see with the design submittal.

Specifically, to satisfy minimum requirements 1-5 or 1-9: 

  • Please include the information required per Vol I, section 3.1.1 items 1 through 3 under ‘The analysis shall include, at a minimum, the following information for projects required to meet Minimum requirements 1-5’ or ‘The analysis shall include, at a minimum , the following information for projects required to meet Minimum requirements 1-9’ as applicable.
  • Include all information in your design submittal as required in section 3.1.5.
  • Per Volume I, section 3.1.6, a SWPPP (Stormwater Pollution Prevention Plan) must be included with your submittal. Requirements for the SWPPP are included in Volume II section 3.2 of the SMMWW
  • Please follow Vol. I, section 3.1.7 closely regarding information required in the Stormwater report including an Operations and maintenance manual and maintenance agreement for the onsite stormwater controls. The maintenance agreement can be found in the City Standards Appendix C. After review the maintenance agreement will have to be recorded through the County Assessor. A copy of this document will then have to be supplied to the City to keep on record. The owner will need to read the agreement to make sure they understand what their responsibilities are.

If per the flow chart, you are only required to address Minimum requirement #2 then you must provide us with the flow chart filled out to justifying the determination and a sediment and erosion control site plan that addresses the 13 elements specified in the 2014 SMMWW.

You are required to submit a sediment and erosion control site plan with every building permit application. In instances of (re)development where the site will be proposing less than 2000 square feet of new or replaced hard surface a sediment and erosion control site plan will be required to address the 13 elements mentioned in Volume II of the 2012 Stormwater Management Manual for Western Washington(2012 SMMWW). All of the elements may not be applicable depending on the site size or topography. A link to Volume II of this document discussing each element in detail is:

  • If the new plus replaced hard surface is less than 2000 square feet the sediment and erosion control Site Plan submitted with for the building permit application can be fairly rudimentary as long as you include the applicable City and 2012 SMMWW BMP details with the submittal (for example: Show clearing limits, construction access, silt fence, and/or drainage inlet protection as required. Include any details, notes or call outs required to give specific information about the BMPs proposed or to address any other element depending on the situation). Applicable City standards could be located in sections 2 ( or 5 ( of the Standard City details. Along with any other details required, please ensure that Standard City detail 05.02.01 is included with the Sediment and erosion control site plan submittal.
The cost of review for the Stormwater site plan is $260 plus $130 per hour for any time required to review the plans submitted beyond the first 2 hours. 

If you have any questions regarding these requirements please contact Paul Marrinan, PE at 253-841-5498 or Mark Higginson, PE at 253-841-5559

SFR Resources - coming soon