1. Permit Required. A building permit is required for all retaining walls with a height greater than four (4) feet. For the purpose of determining if a building permit is required for a retaining wall, height is measured from the bottom of the foundation, footing, or wall system, to the top of the wall. For the purpose of evaluating the height of a retaining wall for compliance with the standards of this code, height shall be measured from finished grade in accordance with MKZ Section 19.95.30 (D). The submittals for a building permit shall include drawings stamped and signed by a professional engineer licensed by the State of Utah. Drawings shall include, at a minimum, details of the wall design, and a site plan depicting existing and proposed elevations on either side of the wall. The design engineer shall inspect the construction of the wall and certify in writing that the wall was built per the approved design, and shall submit that certification to the City within fourteen (14) days of the completion of the retaining wall.
2. Retaining walls are not considered double fences.
3. Retaining walls may not be used to create additional surface parking or vehicular access on a residential lot.
4. Retaining walls are subject to all requirements of this chapter and any other applicable requirements including setbacks.
5. Design Standards for Retaining Walls:
   1. If a single retaining wall is used, one (1) vertical retaining wall up to eight (8) feet in height is permitted to reduce excavation and embankment.
   2. Terracing is limited to two (2) walls with a maximum vertical height of six (6) feet each. The width of a terrace shall be a minimum of a one to one (1:1) ratio with the height of the wall. Terraces are measured from the back of the lower wall to the face of the upper wall. Terraces created between retaining walls shall be permanently landscaped or revegetated as required by this Chapter.
   3. Front yard retaining walls shall be no more than four (4) feet in height and shall include planting terraces of at least four (4) feet in width.
   4. Retaining walls are considered a part of the fence height. No fences shall be installed on the top of a front yard retaining wall or within four (4) feet parallel to the top of a retaining wall.
   5. Residential properties that are not in the Foothills and Canyons Overlay Zone and that have slopes that are greater than 30 percent are eligible for an exemption to the above requirements, subject to a conditional use permit that follows the process and meets the standards of approval established in MKZ 19.84, and subject to the following additional standards:
      1. No wall may be greater than sixteen (16) feet in height, as measured from finished grade.
      2. Walls may be terraced. Terraces must be at least three feet in depth.
      3. Walls visible from rights-of-way must include landscaping, including at least one tree planted at a minimum of 2” caliper, spaced every 30 lineal feet along the retaining wall.

Figure 19.95 -1 Retaining Wall Terracing