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HomeMy Public PortalAboutResolution 16-10 Stormwater Design Criteria ModificationsCity of McCall RESOLUTION NO. 16-10 A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF McCALL, VALLEY COUNTY, STATE OF IDAHO, APPROVING STORMWATER DESIGN CRITERIA MODIFICATIONS TO THE CITY OF MCCALL'S DRAINAGE MANAGEMENT GUIDELINES. WHEREAS, Ordinance 822 and Title 9, "Subdivision and Development Regulations" of the McCall City Code authorizes the use of the Drainage Management Guidelines (Toothman-Orton Engineers, 1997) for designing stormwater management systems and preparing stormwater drainage reports; and WHEREAS, the City Council of the City of McCall has determined that it would benefit future land development, improve stormwater management facility design, and facilitate engineering approval and administration of stormwater regulations within the City, to adopt certain design criteria defined in this resolution: NOW, THEREFORE, BE IT RESOLVED BY THE MAYOR AND COUNCIL OF THE CITY OF McCALL, IDAHO, AS FOLLOWS: Section 1: The following alternative criteria may be used for sizing first flush treatment systems or other detention systems where the 2 year, 24 hour storm is currently identified: A. Storm Size = 0.81", 95% storm based on McCall historic rainfall (1960-2015) B. When site specific soils information has been provided and validated by a geotechnical or otherwise qualified professional engineer or published soils report, such soil definitions may be considered for sizing first flush water quality treatment systems. Final approval of alternative soil classifications must be affirmed by the City Engineer. For all other hydraulic modeling (peak flow attenuation, conveyance pipe sizing, etc.) Type C soils, as defined in the Drainage Management Guidelines (Toothman-Orton Engineering, 1997), shall be used. Section 2: For purposes of sizing stormwater management facilities (excluding first flush water quality treatment facilities), the following 24-hour storm sizes shall be used: A. 10-year storm = 1.83 inches B. 25-year storm = 2.05 inches C. 100-year storm = 2.32 inches Resolution 16-10 Stormwater Criteria March 24, 2016 Page 1 of 2 Section 3: This Resolution shall be in full force and effect immediately upon its adoption and approval. PASSED and approved by the City Council of the City of McCall this 24 day of March, 2016. ATTEST: 1 certify that the above Resolution was duly adopted by the City Council of the City of McCall on March 24, 2016 by the following vote: Ayes: 3 Noes: -e - Absent: o) Resolution 16-10 Stormwater Criteria March 24, 2016 Page 2 of 2