The Highway Runoff Manual is the guidance that WSDOT, engineering consultants, and many local agencies use to design stormwater systems for transportation projects. Together with WSDOT's Hydraulics Manual, (pdf 11.06 mb) the HRM provides tools for designing effective stormwater collection, conveyance, and treatment systems for highways, ferry terminals, park and ride lots, and other transportation-related facilities.
The Highway Runoff Manual represents years of extensive research, collaboration, and negotiation by an interdisciplinary technical team of water quality, stormwater, and erosion control specialists; designers; hydrologists; geotechnical and hydraulics engineers; landscape architects; and maintenance staff. The technical team also includes several county representatives and benefits from a close working relationship with Washington State Department of Ecology (Ecology) staff, with work also contributed by consultants and outside reviewers. The technical team recognized that it is inefficient, and in some instances ineffective, to try to emulate how local jurisdictions manage runoff from residential, commercial, and industrial land uses. Consequently, their approach to developing the HRM takes into consideration that WSDOT:
- Needs a statewide approach for managing stormwater that recognizes the differences in climate, soils, and land uses.
- Has limited control of pollutants entering its right of way (including pollutants generated from atmospheric deposition, vehicle operation, litter, organic debris, and surrounding land uses).
- Highway projects are linear in nature and, as such, are faced with practical limitations in terms of locating and maintaining stormwater treatment facilities within state-owned right of way.
- Lacks funding mechanisms (such as stormwater utility fees) and land use controls (zoning and land use ordinances) available to local governments.
- Must be accountable to taxpayers to provide cost-effective stormwater facilities.
The HRM receives periodic updates to enhance content clarity as well as reflect changes in the regulatory landscape, advancements in stormwater management, and improvements in design tools.
Comments and suggestions for improving the HRM should be e-mailed to:
firstname.lastname@example.org or mailed to:
Highway Runoff Manual
Attention: HRM Program Manager
PO Box 47329
Olympia, WA 98504-7329
Highway Runoff Manual Revision
The Washington State Department of Transportation (WSDOT) is planning a major revision of the 2011 Highway Runoff Manual (HRM) to correspond with the scheduled 2014 reissuance of WSDOT’s NPDES municipal stormwater permit. The HRM revision is intended to:
- verify methodologies and assumptions
- address Low Impact Development options
- clarify and streamline design guidance and procedures
- update requirements and correct errors
Our goal is to have the revised HRM approved by the Department of Ecology as equivalent to Ecology’s stormwater manuals and approved for use under the 2014 reissued NPDES permit. To aid in the manual’s revision process, we are asking for your suggestions on how we can improve the current HRM’s usability, clarity, organization, and layout.
We would also like your suggestions for potential new Best Management Practices (BMPs), design or testing methodologies, and research topics that would be applicable for highway projects. The 2011 HRM is located at: http://www.wsdot.wa.gov/Publications/Manuals/M31-16.htm
The comments received will form the basis of guiding the HRM revision. To submit comments, please do the following:
- download and use the 2011 HRM Comment Form (xlsx, 164kb) and be as specific as possible with your comments;
- provide your proposed solution in the proposed resolution column and designate a priority in the priority for each suggestion; and
- consolidate comments from your organization to limit the amount of redundant comments and the number of comment forms
Return completed comment spreadsheets electronically to Mark Maurer at email@example.com by October 12, 2012.
Below are the post publication updates for chapter 5 of the Highway Runoff Manual. There are two files, one with track changes as well as the final document.
Upon issuance of the WSDOT Municipal Stormwater Permit in February 2009, WSDOT and the Department of Ecology adopted an implementing agreement (pdf 309 KB) calling for WSDOT to apply the June 2008 version of the Highway Runoff Manual throughout Washington State.
Stormwater Retrofit Guidance for WSDOT Projects in the Puget Sound Basin
The February 2009 permit was appealed and the settlement directed WSDOT to retrofit existing pavement, if feasible and cost effective, on projects within the Puget Sound Basin that add more than 5,000 square feet of new impervious surface.
HRM Section 3-4.1 gives guidance on this stormwater retrofit requirement. The Retrofit Cost-Effectiveness and Feasibility (RCEF) document gives the designer detailed instructions on how to perform the analysis. The designer must use the guidelines contained in RCEF along with the information in HRM Section 3-4.1 to complete the analysis. Include the completed RCEF analysis in the project’s hydraulic report.
Training on the analysis methods used to design stormwater runoff treatment and flow control facilities has been incorporated into the HQ Hydraulics Section's curriculum. Training on guidance and procedures for temporary construction-related erosion and sediment control facilities has been incorporated into the Environmental Services' erosion and sediment control program curriculum. Training for applying other elements of the HRM is under development. All consultants who prepare Hydraulics Reports for WSDOT must have completed the 2008 Highway Runoff Manual training course. 2008 HRM training is required for WSDOT staff who write Hydraulics Reports.
To receive e-mails announcing updates, training opportunities, and improvements in design tools, please subscribe to the Stormwater Issues listserve.
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To receive announcements for updates to the HRM, please subscribe to the HRM Update listserve.
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Frequently Asked Questions (FAQs)
The HRM FAQs page answers a variety of questions about the Highway Runoff Manual.