The subdivider shall construct all necessary facilities, including underground pipe, inlets, catch basins, open drainage ditches, detention and/or retention basins, as determined by the City, to provide for the adequate disposal of subsurface and surface water and maintenance of natural drainage courses. All storm drainage facilities within the subdivision shall connect to an adequate drainage outlet. Surface water discharged from the development, shall be at no greater rate, after the development than it was before the development.
(l) Easements for closed conduits and appurtenances thereof. An easement of not less than twenty feet in width and sufficient to contain the closed conduit shall be dedicated on the final map of the subdivision as "Drainage Easement." Drainage easements for closed conduits shall not traverse a building site and shall insofar as possible, be placed along or adjacent to lot boundary lines in a straight alignment without angle points.
(2) Easement along streams. Whenever any stream or important surface drainage course is located within the area being subdivided, the subdivider shall provide a permanent easement of sufficient width dedicated to the proper authority for the purpose of widening, deepening, relocating, improving or protecting the stream for drainage.