2010 Drainage Design and Erosion Control Manual 

The 2010 Drainage Design and Erosion Control Manual (DDECM) sets standards for reducing and managing stormwater runoff for all new development and redevelopment projects within the City of Tumwater.

The 2010 DDECM replaces the 1994 DDECM and the 2005 Department of Ecology Stormwater Manual for Western Washington (DOE Manual), which was implemented for qualifying projects as required by the City's NPDES permit since 2007. While this update replaces the DOE Manual, it is still considered "technically equivalent" and consistent with the 2005 manual.

The 2010 DDECM is applicable to all development and redevelopment projects within the City of Tumwater.

Printer-friendly versions (PDFs) of the current 2010 DDECM are available below.

2010 DRAINAGE DESIGN AND EROSION CONTROL MANUAL FOR THURSTON COUNTY
FACT SHEETS
MODELING INFORMATION
  • The 2010 DDECM requires the use of the Western Washington Hydrologic Model, Version 3 (WWHM3) with Thurston County enhancements for BMP design. The Thurston County enhancements include the use of additional rain gage stations and 15-minute time steps and also include a recharge calculator to demonstrate minimum infiltration requirements for projects. The program is available for download by clicking here.
  • Guidance for Using the Recharge Calculation in WWHM3 with Thurston County Enhancements (PDF)
  • Department of Ecology memo approving Western Washington Hydrologic Model with Thurston County Enhancements (PDF)
2010 DDECM Contacts

Have a question or comment? Fill out this form and return it to the Water Resources department.

Development Services – responsible for implementing the manual and reviewing projects for compliance with City standards.              

Contact: Matt Webb, Engineer III
Phone: 360-754-4180
Email: mwebb@ci.tumwater.wa.us

Public  Works – responsible for administration of the manual and providing updates as necessary.  Public Works also oversees the maintenance and inspection program of public and private facilities.

Contact: Dan Smith, Water Resources Program Manager
Phone: 360-754-4140
Email: desmith@ci.tumwater.wa.us

Updated: June 4, 2010