(a) Hydrologic Design. The hydrologic methods and criteria used to estimate storm water runoff facilities shall comply with the Ohio Department of Transportation Location and Design Manual, Volume II – Drainage Design, latest edition, unless otherwise stated in these regulations or as required by the City Engineer. Those waterways and drainage facilities set forth in the most current City-adopted master plan (if available) for drainage in the City of Louisville shall be designed and constructed for the flow rates and quantities of water indicated in such master plan.
(b) Hydraulic Design. The hydraulic design of storm collection facilities shall comply with the Ohio Department of Transportation Location and Design Manual, Volume II – Drainage Design, latest edition, unless otherwise stated in these regulations or as required by the City Engineer.
Given the type of drainage structure to be designed, the rate of runoff shall be computed using the storm frequencies given below unless otherwise required by the City Engineer:
Structure Storm Frequency (Years) Storm Sewers 10 (Just Full Capacity) 25 (Hydraulic Grade Line) Open Channels 10 Culverts 25 Bridges 25 Catch Basin Spacing (As per ODOT L&D Vol. II) |
The design frequency to be considered for an individual structure may be altered by the City where the health and safety of the residents would be endangered by the hazards of flood waters or increased flows. All structures located in a designated flood zone shall meet the requirements of Chapter 1323.
Site grading within the development shall be such that all lots will easily drain and structures will be protected from the 100-year flood elevation.
(c) Structural Design. All bridges, culverts, pipes, catch basin, manholes, inlet structures, etc. constructed within the development shall conform to the latest editions of the Ohio Department of Transportation Location and Design Manual, Volume II – Drainage Design, Bridge Design Manual, the Construction and Material Specifications, and the Roadway and Structural Standard Construction Drawings. Structural design of all drainage facilities shall be subject to the approval of the City Engineer.
(d) Additional Requirements.
(1) Open channels. Minimum center line radius of constructed channel shall be a minimum of five times the top width of the channel. Minimum bottom width of constructed channels shall be two feet. Earth channels constructed within the development shall have side slope of 2:1 or flatter. Revetment, bank stabilization and stream bed stabilization along constructed or natural channels will be required as per the Ohio Department of Transportation Location and Design Manual, Volume II – Drainage Design, latest edition.
Open channels shall be designed to avoid roadside hazards as per Ohio Department of Transportation Location and Design Manual, Volume I – Roadway Design, latest edition.
The top of the bank shall be so graded that side drainage will enter channel only at points where structures are provided to prevent bank erosion. The design of open channels shall be in accordance with the Bureau of Public Roads publication Design of Roadside Drainage Channels, Hydraulic Design Series No. 4. If this publication conflicts with the Planning and Zoning Code, the stricter of the two shall be met.
(2) Closed conduits. The alignment of closed conduits shall be as nearly straight as practicable without undue bends and angle points; manholes or catch basins shall be provided at all angle points and at intervals not to exceed 300 feet along the conduit. Inverted siphons shall not be permitted except for temporary structures.
(3) Bridges. All drainage structures having a span of ten feet or greater and all pipes having a diameter or span of ten feet or greater shall be designated as bridges. All calculations and plans pertaining to bridges shall require both preliminary and final approval from the County Bridge Engineer. The hydraulic and structural design of all bridges shall be as per the current version of the Ohio Department of Transportation Bridge Design Manual.
(4) Culverts. Culverts shall be designed to avoid roadside hazards as per the Ohio Department of Transportation Location and Design Manual, Volume I – Roadway Design, latest edition. Culverts shall be designed to meet the allowable headwater criteria in the Ohio Department of Transportation Location and Design Manual, Volume II – Drainage Design, with the design storm per Section 1164.03(c).