Buried structures greater than 10 feet long require wing walls. Wing walls and aprons are required with reinforced concrete box culverts and other types of buried structures. Wing walls shall be a minimum of 10 feet in length and shall be increased based on the potential impacts of lateral migration as assessed by the hydraulics engineer of record. In lieu of using wing walls, box culvert extensions may be acceptable if site conditions are suitable and the State Hydraulics Office approves. Wing walls may also be modified for use on circular culverts in areas of severe scour problems (Figure 3-7). When a modified wing wall is used fo
r circular pipe, the PEO must address the structural details involved in the joining of the circular pipe to the square portion of the wing wall. The State Hydraulics Office can assist in this design.
