Fences, walls and decorative posts in public (P), recreation (R), or open space (OS) zones may be constructed of wood, stone, brick, wrought iron, chain-link and wire mesh. They shall not exceed three and one-half feet in height when located within a required front setback, and shall not exceed six feet when located in any other part of the setback area. All outdoor trash or refuse containers serving offices, community infrastructure, or other nonresidential uses shall be screened on all sides from public view by a minimum five-and-one-half-foot-high wall or fence.