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Operations Office
2001 DRAFT HIGHWAY RUNOFF MANUAL
Until the 2003 Highway Runoff Manual (HRM) is competed, IL 4020.02 and LA Instructional Letter 03-02 provide guidance for project development. Included in that guidance for local agencies is an interim step where the 2001 Draft HRM would be used for projects advertised before October 2005.
One of the primary changes in the 2001 draft addresses ESA issues. It attempts to consider sensitive areas and evaluate their treatment level as Protective, Corrective or No Action, which was the basis for how to apply the 140% Rule.
In Section 3-3.5 and 6-2.1 there were a few paragraphs added that discuss the use of a continuous model (KCRTS or HSPF) using "pre-disturbance" conditions (as opposed to pre-European baseline) as an alternative design method to applying the volume correction factor for flow control but did not go into detail.
Chapter 6 assumed that treatment would be for TSS unless specific pollutants are targeted through a TMDL or watershed plan. However, the 2001 draft never went into any detail about other types of BMPs that could be used to remove those pollutants.
For comments or suggestions contact:
Ron Pate
Highways and Local Programs
E-mail:paterd@wsdot.wa.gov
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