Where curbs and gutters are not required, by the terms of this chapter or as determined by the commission through the modification procedure, roadside swales shall be constructed according to the following specifications:

    A.    Design Standards. The design of the swales shall take into account the volumes and flows determined in the drainage report. Street shoulders, side slopes and ditches shall be designed in accordance with specifications determined by the board.

    B.    Culverts. Where necessary (as determined by the engineering department), culverts shall be required to be installed under the roadway. The size of the culvert shall be determined by the amount of stormwater flow, but not less than twelve inches in diameter. All culverts shall extend five feet beyond either edge of the paved roadway and terminate with the head walls or flared-end sections. (Prior code § 28-41)