RETENTION BASINS

Mesa City Code § 11-33-6

in effect

11-33-6: - RETENTION BASINS A. In both residential and nonresidential developments, the basin design shall be incorporated with the overall site plan by providing access, landscape, amenities. B. Retention basin layout shall be irregular in shape, contoured and designed as an integral part of the Landscaping theme, and shall not take on the appearance of a ditch. The depth of water in retention basins shall not exceed 3 feet 6 inches. C. A 3-foot transition area shall be provided where the retention basin side exceeds 6-to-1 slope measured horizontal to vertical and basin is adjacent to Right-Of-Way and Sidewalks. Transition area shall be less than 6-to-1 slope. A maximum 4-to-1 slope allowed in other locations. D. Retaining walls shall not exceed 25 percent of the basin perimeter (measured at the high waterline). The maximum height of retaining walls is 18 inches. E. Retention basins along public Streets that incorporate retaining walls shall utilize catch basins and pipes to collect and direct water to the bottom of the basins. Where retention basins occur along arterial Streets, berms shall be provided along 33 % of basin frontage. Berms are to be 4-to-1 (horizontal-to-vertical) maximum slope, 2 feet high. Within public Right-Of-Way maximum slope is 6 to 1. Berming shall not obstruct run-off from Streets into the retention basin. F. Retention basin design shall provide consolidated basins. Multiple, small retention areas are not acceptable unless basins are interconnected and designed per the City of Mesa Engineering Manual. G. Landscaping shall be provided in all areas of the retention basin (slope, top, and bottom).

Source: City of Mesa, Arizona, Mesa City Code and City Charter (Municode Library, library.municode.com)URL: https://library.municode.com/az/mesa/codes/code_of_ordinances?nodeId=COOR_TIT11ZOOR_ART4DERE_CH33LA_11-33-6REBAFetched: 11/1/2026