Storm sewer systems and roadway drainage including catch basins, pipes, culverts, swales, ditches, and other open channels shall be designed in accordance with the latest editions of the Ohio Department of Transportation's Location and Design Manual, Volume Two - Drainage Design and Construction and Materials Specifications.
(a) Provide calculations for the storm sewer systems. All storm sewer systems shall be designed to flow just full for a 10-year frequency storm, except where more stringent requirements are noted in the Location and Design Manual. For roadway pipe design, check the hydraulic grade line does not exceed the grate elevations based on a 25-year frequency storm.
(b) Provide calculations for the inlet spacing and pavement spread. Allowable pavement spread shall be six feet from the curb for a 10-year frequency storm.
(c) All commercial, institutional and industrial sites, condominium developments, planned urban developments and subdivisions shall be designed with supplemental conveyance systems (i.e. swales, ditches, channels, roadway, etc.) to convey up to the 100-year frequency storm flow, in conjunction with the designed storm sewers, to the proposed detention or retention systems.
(d) Provide a storm sewer system and roadway drainage drawing. Perform field surveying as necessary to insure that this drawing is an accurate representation of actual field conditions. The scale of this drawing must be sufficient to clearly present the following information:
(1) Existing and proposed elevation contours at an interval of two feet or less. Contour lines shall be labeled frequently enough to be easily read and interpreted.
(2) All of the individual surface areas that drain to each intercepting structure or the storm sewer system must be submitted. The areas must be numbered or labeled to match the calculations.
(3) The path used to calculate the time of concentration for each individual drainage area. Indicate the types of flow and provide calculations.
(e) An adequate outlet must be provided for all proposed drainage systems, such as an existing ditch, stream, river, storm sewer, pond, lake or proposed detention/retention facility. The downstream outlet must be able to accommodate the flow of storm water from the proposed drainage system.
(f) Provide headwalls, energy dissipaters, rip-rap, erosion control mats, and other measures, as necessary, at all outlets to prevent erosion.
(g) (1) Storm sewer and drainage system materials and construction shall be in accordance with the latest edition of Ohio Department of Transportation (ODOT) Construction and Materials Specifications (CMS) for pipe, catch basins, manholes, excavation, rock channel protection and seeding and mulching.
(2) Storm sewers beneath pavement and five feet outside the edge of pavement shall be ODOT CMS Item 611, Conduit, Type "B".
(3) Storm sewer five feet outside of the edge of pavement shall be ODOT CMS Item 611 Conduit, Type "C".
(Ord. 15-O-2820, passed 5-19-2015)