City of Kennewick
Stormwater Management Manual for Eastern Washington (SWMMEW)
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Regional Ecology SWMMEW used for Kennewick MS4; confirm city adoption ordinance / local amendments.
Other manuals in Washington: City of Bellevue, City of Bellingham, City of Everett, City of Lacey, City of Olympia, City of Seattle, City of Seattle, City of Tacoma, City of Vancouver, King County, Spokane County / City of Spokane / City of Spokane Valley, Washington, Washington State Department of Transportation (WSDOT)
Document Metadata
Jurisdiction level
City
No evidence cited
State
Washington
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Version / edition
July 2024 (Ecology Pub. 24-10-014)
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Adoption / effective date
2024-07
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Last revised date
2024-07
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Relationship to state manual
adopts state manual directly
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Design Criteria
Design storm return periods (years)
2-year
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Water quality volume method
Ecology SWMMEW Core Element 5 (Runoff Treatment): water quality design storm is the 6-month, 24-hour precipitation computed as Pwqs = Cwqs × P2yr24hr (Cwqs by climate region, Table 4.5). Runoff treatment BMPs sized per Ch.6; infiltration BMPs must infiltrate the 6-month, 24-hour design storm where required. Kennewick is in Eastern Washington — use SWMMEW rather than SWMMWW.
“The frequency of the water quality design storm is a 6-month recurrence interval or return period”
Ch.4 / Equation 4.1
Peak flow calculation method(s)
Core Element 6 Flow Control, Hydrologic analysis methods in SWMMEW Ch.4, Runoff treatment and flow control BMP library (Ch.6)
No evidence cited
Hydrologic/hydraulic software
Not found in document
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Approved BMP categories
Runoff treatment BMPs (infiltration, biofiltration, wetpool, media filtration), Flow control BMPs, LID BMPs, Pretreatment BMPs
No evidence cited