General Grading and Drainage Requirements

Basically, grading and drainage submittal documents must meet Snohomish County Code Chapters 30.63A, 30.63B and Engineering Design and Development Standards (EDDS), and the Snohomish County Drainage Manual. There are development restrictions and code requirements related to Critical Areas (link below). For example, development is prohibited within Channel Migration Zones (SCC 30.63B.330(3)a). Developments within Little Bear Creek Watershed Southwest UGA expansion areas must use Low Impact Development techniques where possible (SCC 30.63C.025). There are unique frontage improvement standards required for portions of Serene Way.  In Lake Stevens UGA, storm drain tightlines are required over steep ravines (SCC 30.63A.225). And for developments within Lake Stevens UGA Weiser Creek, Burri Creek or Fox Creek basins, see SCC 30.63A.226 regarding storm detention requirements.  Development requirements of outside agencies such as the Snohomish Health District, Washington Dept. of Fish and Wildlife HPA permits, federal Army Corp of Engineers, and WSDOT permits are the applicant’s responsibility to research and meet. Plans should reflect any requirements of those agencies.

Technical drainage design requirements are found in the Snohomish County Drainage Manual, which is composed of serveral documents that can be downloaded from the Drainage Manual web page linked above.

Paper or CD versions of the EDDS standards are available from the Department of Public Works.

Please go to the following links for questions on status, requests for appointments, or general questions askpermittech. For all other inquiries, please call or visit the Customer Service Center at the address shown below.

Complete and submit the appropriate checklist because incomplete submittals may be rejected.

All Developments: All new development must use adequate temporary erosion control Best Management Practices (BMP’s).  If developing in a floodplain contact the Flood Hazard Specialist at 425-388-3311 extension 2731. If your development will occur within 300 feet of a FWHCA fish bearing stream, demonstrate compliance with SCC 30.62A.320(1)(c) and Rule 6225: Chapter 30.62A SCC Infiltration Standards.  The following links apply:

Engineering Design and Development Standards (EDDS)
Snohomish County Code (SCC)
Drainage Ordinance 30.63A
Grading Ordinance 30.63B
Critical Area Regulations 30.62A, 30.62B, and 30.62C
Channel Migration Zones
General Notes

Full Drainage Plan: Major Development proposals (more than 5,000 sq. ft. of new impervious surface area, or more than 5,000 cubic yards of gross cut or fill) generally require storm water detention and water quality treatment facilities designed by a professional engineer licensed in Washington. The following links apply:

Construction/Full Drainage Plan Checklist
Pollution Source Control BMP's:  Snohomish County Drainage Manual, Vol IV
Drainage Facility Maintenance Covenant (DFMC) – subdivisions
Drainage Facility Maintenance Covenant (DFMC) – other
DFMC - Applicant's Submittal Instructions
Record Drawings (as-built) Checklist
Rule 3044 - Standards for Stormwater Pollution Prevention Plans
2005 DOE Stormwater Management Manual, Vol. II
Drainage Information Summary Form

Targeted Drainage Plan: Other Developments (more than 200 but less than 5,000 sq. ft. of new impervious surface area) generally have no detention or water quality treatment requirements. A Targeted Drainage Plan can either be for construction, or can be a conceptual plan usually associated with a land use action going to hearing. The following links apply:

Targeted Drainage Plan Checklist

Grading Plan: A grading permit is required for all grading that does not meet the exemption requirements of 30.63B. When no impervious surfaces are proposed but a grading permit is still required, use the following checklist:

Grading Plan Submittal Checklist

Low Impact Development (LID) is now available for projects meeting LID Ordinance 30.63C, and is offered as an alternative.  Use the 2005 DOE Manual if claiming credits in your detention pond sizing for using LID techniques.  See the following applicable links:

Low Impact Development Manual 
Request for Low Impact Development (LID)  Pre-Application Meeting
Notice
Stormwater Management Manual for Western Washington (revised 2005)

Other Information Links:

Drainage Needs Report and Maps
EDDS Deviation Request
NPDES Draft Ordinance
Public Drainage Easement Form
Public Drainage Easement - Applicant's Submittal Checklist
Waiver and Modification Request (pdf)
Waiver and Modification Request (for computer entry)
W.S.D.O.T. Highway Runoff Manual
W.S.D.O.T. Hydraulics Manual

Location & Phone Number:

Administration Building, 2nd Floor East, 3000 Rockefeller, Everett, Washington 98201

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