Title
Drainage Design and Erosion Control Manual Update Project Briefing
Recommended Action
Discussion only. No action requested.
Report Issue:
Receive a briefing on the Drainage Design and Erosion Control Manual update project.
Staff Contact:
James Patton, PE, Senior Engineer, Public Works Water Resources, 360.753.8749
Fran Love, Project Engineer, Public Works Water Resources, 360.753.8397
Presenter:
James Patton, PE
Background and Analysis:
The City of Olympia (City) Drainage Design and Erosion Control Manual (DDECM) sets standards and provides guidance on the measures necessary to control the quantity and quality of stormwater produced by new development and redevelopment within the City of Olympia.
To ensure that the City continues to effectively manage stormwater from new development, redevelopment and construction activities, the City’s 2024-2029 Western Washington Phase II Municipal Stormwater Permit (Permit) requires a review of our DDECM for equivalency with the 2024 Stormwater Management Manual for Western Washington (Ecology Manual). The review and any necessary revisions must be completed by June 30, 2027 to maintain compliance with the Permit.
The City’s DDECM was last updated in November 2022 and is equivalent to the 2019 Ecology Manual, as was required by the City’s previous Permit.
A workgroup was formed to review and update the DDECM. The workgroup consists of City staff responsible for public and private development review, permitting, inspection, maintenance and Permit compliance.
To ensure that the 2027 DDECM is fully consistent with the 2024 Ecology manual, the workgroup used the 2024 Ecology manual as its “base” and then added Olympia-specific requirements. By taking this approach, the usability enhancements in the 2024 Ecology Manual, which include consolidating repetitive information, revising text for clarity, and reordering sections for a better flow of concepts, are incorporated.
Revisions to the 2024 Ecology Manu...
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