§ 10-48. Retaining walls.

(a)

Permit required. A building permit shall be required for any retaining wall that exceeds three feet in exposed wall height or exceeds two feet in exposed wall height and supports a surcharge. A building permit application shall require a site plan showing the location, extent, and height of the retaining wall in relation to any building structure, pool, property lines, and public utility easements. It shall also require complete construction details of the retaining wall and structural calculations for the wall, both stamped and signed by a professional engineer.

(b)

Definitions. The following words, terms and phrases, when used in this section, shall have the meanings ascribed to them in this subsection, except where the context clearly indicates a different meaning:

Exposed wall height means the vertical distance measure from the finish grade at the bottom of the wall (lower soil grade) to the finish grade at the top of the wall (upper soil grade). This height does not include the wall and depth of footing below grade.

Retaining wall means a wall designed to resist lateral earth and/or fluid pressures, including any surcharge, in accordance with accepted engineering practice.

Surcharge means a vertical load imposed on the retained soil that may impose a lateral force in addition to the lateral earth pressure of the retained soil. Examples of surcharges include sloping retained soil, structure footings supported by the retained soil, adjacent vehicle loads supported by the retained soil, and solid fences that are attached or directly adjacent to a retaining wall when wind pressures act on the fence.

(c)

Tiered retaining walls. Use of tiered walls is a special condition where two or more short walls, horizontally offset from one another, are used in lieu of a single tall retaining wall. When tiered walls are not properly offset from each other, the upper wall may impose a surcharge condition on the lower wall. In order for the walls to be treated as separate retaining walls, a general rule of thumb is that the tiered walls be horizontally offset by a minimum distance of two times the exposed wall height of the lower wall. For example, two tiered retaining walls, each with an exposed wall height of three feet and level backfill, which are horizontally offset by a distance of two feet, would be treated as a single six-foot-tall wall. As a result, a building permit would be required.

(Ord. of 8-11-2016, § 1.29)