(A) Within subdivision streets' rights-of-way, surface water, sump pump discharge, and geothermal heat pump water discharge shall be carried away by enclosed storm drainage systems, not including subsurface drains. Downspouts shall not be discharged directly into any part of the enclosed storm drainage system. Storm drainage pipes or systems, subsurface drains or sump pump outlets shall not discharge into roadside ditches or over curbs. All pipes, culverts, inlets, cleanouts and manholes shall be constructed in accordance with plans and specifications approved by all governmental agencies having jurisdiction over the project drainage.
(B) Systems shall be designed to prevent flooding of roads by a storm in accordance with the following criteria:
(1) Local Roads - Maintain one lane at ten foot minimum clear width for a ten year storm. For greater storm frequencies, no greater than six inch depth of flooding shall be allowed in the road.
(2) Collectors and Arterials - meet INDOT spread criteria.
(C) Culverts and storm sewers shall be designed for a ten year storm in accordance with the requirements of the town and installed to the approved elevations shown on approved construction plans. Culverts for major roads shall be designed such that the road shall not be overtopped by a 25 year storm event. Minimum diameter for storm sewers shall be 12". Minimum diameter for culverts shall be 15" under driveways and 36" under roadways. End sections made of the same material as the pipe shall be used for culverts. All storm sewer pipes shall designed to ensure a minimum flow velocity of three feet per second.
(Ord. 1999-06, passed 6-8-99)