All commercial, industrial, office, recreational, and multifamily tracts deeper than one hundred feet (100') measured from the right-of-way line shall have an internal drainage system. The internal drainage system shall collect all site runoff beyond one hundred feet (100') from the right-of-way line into a storm sewer system that shall connect to the public drainage facilities in the area, except with specific approval. The one-hundred-foot (100') area adjacent to the right-of-way may sheet flow to the roadway drainage system if the roadway system is designed to accommodate the additional sheet flow from development.
(1) The internal site storm sewer shall be connected to a public storm sewer at a manhole or at an inlet adjoining the site. The site drainage outfall shall be connected to the nearest existing drainage system with adequate capacity to serve the drainage area. Where extension of the existing drainage system is required, all costs for extension shall be the responsibility of the development.
(2) All storm sewers extended into a public right-of-way or easement shall be reinforced concrete pipe or high-performance polypropylene pipe (PP) ASTM F2881 pipe at least twelve inches (12") in diameter. Storm sewers shall be reinforced concrete pipe, ASTM C-76, class III or high-performance polypropylene pipe (gray) [and] shall meet or exceed ASTM F2881 “Standard Specifications for 12" to 60" Polypropylene Dual Wall Pipe and Fittings for Non-Pressure Storm Sewer Applications.”
(3) All internal facilities shall be designed by a registered professional engineer and shall be sized to drain the site in accordance with these standards.
(4) Drainage calculations shall be submitted with all site development plans.
(5) When the site drains directly into a Wharton County drainage facility and/or into a highway right-of-way, the appropriate governmental entity (entities) shall approve the site development connection to public facilities.
(Ordinance 2019-12 adopted 4/22/19)