All primary drainage channels lying within or immediately adjacent to the subdivision shall meet the following conditions:
A. All land having an elevation below the 50-year maximum flood elevation for the final improved channel and not protected by levies or dikes shall be dedicated for the purpose of providing drainage for public park and/or utility easement use. All dedications for public park purposes will be reviewed and approved by the city council or its designated representatives.
B. The existing channel lying within or immediately adjacent to the subdivision shall be cleaned to provide for the free flow of water, and the channel shall be straightened, widened and improved to the extent required to prevent overflow, resulting from a 50-year frequency rainfall, beyond the limits of the dedicated drainage easement provided for in subsection A of this section.
C. Site improvement shall provide for the grading of all building sites and streets to an elevation where all lots, building areas and streets will not be subject to overflow from a 50-year frequency flood, and in a manner that will provide for the rapid runoff of storm water.
D. Whenever channel improvement is carried out, sodding, backsloping, cribbing and other bank protection shall be designed and constructed to control erosion for the anticipated conditions of flow resulting from a 50-year frequency rainfall.
E. A drainage channel shall not be located in a street easement unless it is placed in an enclosed storm sewer, except as provided below:
1. Unless a paved street surface at least two (2) lanes wide is provided on both sides of a paved channel so as to provide access to abutting properties;
2. Except where lots are platted to back up to the street right of way where the drainage channel is located between the rear lot line and the paved street, provided that there is no access to the rear of the lot from the street, and further provided that at no time in the future shall access be allowed or constructed over the open drainage channel to the rear of a lot so platted. For the purpose of these regulations, a lot which sides is not considered to back up to the street right of way;
3. When a condition outlined in either subsection E1 or E2 of this section is present, adequate space shall be dedicated as right of way to provide for maintenance of the paved drainage channel and its unpaved bank.
F. Culverts, bridges, and other drainage structures shall be constructed in accordance with the specifications and design criteria of the city where the city has present or future maintenance responsibility. (Prior code §7-5)