The Office of Planning (“OP”), in a report dated March 29, 2013, petitioned the Zoning Commission for the District of Columbia (“Zoning Commission” or “Commission”) for text amendments to the Zoning Regulations to define and regulate retaining walls in the R-1 through R-4 Residence Zone Districts. The OP report also served as a prehearing statement. At its regular public meeting on April 8, 2013, the Zoning Commission set the case down for a public hearing. A public hearing was scheduled for and held on July 22, 2013. At the hearing, the Zoning Commission heard testimony from the public and suggested revisions that would clarify the proposed regulations, including how to measure the rear yard restrictions, how to measure a retaining wall of varying height, and to allow greater flexibility in the R-3 and R-4 Zone Districts along alleys. In a supplemental report dated August 29, 2013, and then a corrected supplemental report dated September 4, 2013, OP proposed revised text to clarify how to measure the height of a retaining wall, where such structures may be placed in relationship to the rear property line, and removed the proposal to include a retaining wall in the lot occupancy requirements for the R-3 and R-4 Zone Districts. At the public meeting on September 9, 2013, the Zoning Commission noted comments from a member of the public and offered additional changes to the regulations that would allow greater flexibility for retaining walls located adjacent to alleys, and would permit relief from the regulations as a special exception. The Commission decided not to take proposed action and authorized a notice of second public hearing to allow additional review and public comment of the requested revisions. Since the supplemental OP reports, OP has incorporated revisions to the text and the proposed amendments to the Zoning Regulations, Title 11 DCMR, are as follow: AMEND CHAPTER 1 by adding the following definition to § 199 in alphabetical order: Retaining Wall – a vertical, self-supporting structure constructed of concrete, durable wood, masonry or other material, designed to resist the lateral displacement of soil or other materials. The term shall include concrete walls, crib and bin walls, reinforced or mechanically stabilized earth systems, anchored walls, soil nail walls, multi-tiered systems, boulder walls or other retaining structures. AMEND CHAPTER 4 by adding a new § 413, Retaining Walls, to read as follows: 413 RETAINING WALLS 413.1 In R-1, R-2, R-3, and R-4 Districts a retaining wall may be erected in accordance with the requirements of this section. 413.2 The height of a retaining wall shall be the vertical distance measured from the finished grade at the bottom of the wall to the finished grade at the top of the wall. When the height of a retaining wall varies, the height shall be measured at the highest point of the wall, from the finished grade at the base of the wall at that point. 413.3 Subject to the location-based height limitations of § 413.4 through 413.6, the maximum height of a retaining wall shall be six feet (6 ft.), with the exception of a retaining wall abutting an improved alley in the R-3 or R-4 Districts, which shall have no maximum height. 413.4 A retaining wall shall not exceed four feet (4 ft.) in height in the following locations, unless a lower height is required by § 413.5 and 413.6: (a) Along a street frontage or property line; (b) Within any required side yard; (c) In the R-1 Districts, within twenty-five feet (25 ft.) of the rear property line, as measured from the rear property line inward; and (d) In the R-2, R-3, and R-4 Districts, within twenty feet (20 ft.) of the rear property line, as measured from the rear property line inward. 413.5 A retaining wall located along a street frontage with adjacent existing retaining walls shall not be greater in height than the tallest adjacent existing retaining walls up to the maximum height of four feet (4 ft.) permitted in § 413.4 (a). 413.6 A retaining wall located on any area between the property line and a building restriction line shall not exceed forty-two inches (42 in.) in height. 413.7 In the R-1 and R-2 Districts, the area of a retaining wall that is more than four feet (4 ft.) in height and that elevates the terrain and is back filled with dirt or other fill material shall be included in the calculation of lot occupancy. 413.8 Retaining walls may be tiered or terraced provided there shall be a four foot (4 ft.) landscape area between walls. The landscape area shall be pervious and may not be paved or otherwise covered with impervious materials. The area of a tiered or terraced retaining wall that is more than four feet (4 ft.) in height shall be included in the calculation of lot occupancy. 413.9 The area of a retaining wall described in § 413.7 and 413.8 shall be its length multiplied by the length of the area containing fill that is being held by the retaining wall. 413.10 Retaining walls not meeting the requirements of this section, may be approved by the Board of Zoning Adjustment as a special exception pursuant to § 3104.1. In addition to meeting the general conditions for being granted a special exception as set forth in that section, the applicant must demonstrate that conditions relating to the building, terrain or surrounding area would to make full compliance unduly restrictive, prohibitively costly, or unreasonable.