Where natural drainage channels intersect any street right of way, it shall be the responsibility of the subdivider to have satisfactory bridges and culverts constructed. Where culverts are required, minimum requirements shall be observed as follows:
(1) All culverts shall extend across the entire right-of-way width of the proposed street. The cover over the culvert and its capacity shall be determined by the City Engineer. The minimum diameter of a culvert pipe shall be twelve inches. Depending on existing drainage conditions, head walls may be required.
(2) Driveway culverts shall have a minimum length of twenty feet. The diameter shall be subject to the determination of the City Engineer. The driveway culverts shall be laid so as to maintain the flow lines of the ditch or gutter. Head walls may be required.