Policies & Regulations - Stormwater Drainage Manual
Olympia adopted its 2005 Stormwater Manual in anticipation of the NPDES Phase II Permit being issued by the Washington State Department of Ecology (WDOE). The permit requires implementation of specific stormwater management programs including regulations for new developments. The current manual is based upon the Washington State Department of Ecology's 2001 Western Washington Stormwater Manual.
New Proposed Revisions for 2009
To be in compliance with the now-released NPDES Permit, the City must adopt a manual which is equivalent to the 2005 WDOE Manual. Most of the proposed 2009 changes provide this equivalency. Other proposed revisions respond to community concerns. A Public Hearing was held in July 2009; the Stormwater Drainage Manual is scheduled on the Council consent calendar for adoption on October 20, 2009 as the Drainage Design and Erosion Control Manual for Olympia / October 2009.
Review the Current and Proposed Manuals
Printer-friendly versions (PDFs) of the current 2005 manual and the proposed new manual are available below. For your convenience, we have provided an overview of each volume.
Volume I (Current 2005 Manual) / Volume I (2009 Proposed Manual)
Volume I of this manual serves as an introduction and covers several key elements of developing the Stormwater Site Plan. The remaining volumes of this manual cover Best Management Practices (BMPs) for specific aspects of stormwater management.
Volume II (Current 2005 Version) / Volume II (2009 Proposed Manual)
Volume II covers BMPs for short-term stormwater management at construction sites. Examples include:
- Providing guidance for avoiding adverse stormwater impacts from construction activities on downstream resources and on-site stormwater facilities.
- Minimization of stormwater flows, prevention of soil erosion, and capture of water-borne sediment that has been unavoidably released from exposed soils.
- Protection of water quality from on-site pollutant sources are all readily achievable when the proper BMPs are planned, installed, and properly maintained.
Volume III (Current 2005 Version) / Volume III (2009 Proposed Manual)
Volume III covers hydrologic analysis and BMPs to control flow volumes from developed sites. For example:
- It presents techniques of hydrologic analysis and BMPs related to management of the amount and timing of stormwater flows from developed sites.
- It provides guidance on the estimation and control of stormwater runoff quantity.
Volume IV (Current 2005 Version) / Volume IV (2009 Proposed Manual)
Volume IV addresses BMPs to minimize pollution generated by potential pollution sources at developed sites.
- Prevention of water-quality impacts from potential pollutant sources.
- Source control BMPs are structures or operations that are intended to prevent pollutants from coming into contact with stormwater through physical separation of areas or careful management of activities that are sources of pollutants.
- This volume also identifies certain treatment BMPs that apply to specific types of pollutant sources.
Volume V (Current 2005 Version) / Volume V (2009 Proposed Manual)
Volume V presents BMPs to treat runoff that contains sediment or other pollutants from developed sites.
- BMPs addressing treatment of runoff to remove sediment and other pollutants at developed sites.
- This volume provides guidance for selection, design, and maintenance of permanent runoff treatment facilities.
Contacting Public Works: