Unified Development Ordinance, 4th supplement, September 2017

Part 10A: Unified Development Ordinance City of Raleigh, North Carolina 9 – 30 Effective Date: September 01, 2013 Supp. No. 4 adequate to contain the increased flow levels are first submitted to the City; and 2. Land areas contained within the easement boundaries shall be delineated as flood storage areas. D. The following additional standards shall apply to all streets and driveways crossing watercourses draining 10 acres or more and which are located inside floodprone areas. 1. Any street, driveway, bridge or culvert associated with any street or driveway shall pass the 100 year flood crest, under free flow conditions that will not result in any increase in the elevation of the 10- through 100-year floods above those specified in the Flood Insurance Study, City of Raleigh, Federal Emergency Management Agency, latest publication. 2. If the drainage areas exceed 1 square mile, the maximum rise allowed for the 100-year flood shall not exceed a total of 1 foot above the base flood elevation established for flood hazard soil areas or those elevations specified either in the drainage basin study maps or in the Flood Insurance Study, City of Raleigh, Federal Emergency Management Agency, latest publication. 3. Base flood elevations for return periods of less than 100-years may be increased to exceed 1 foot, provided that the portion of the flood increase which is greater than 1 foot is either limited to the site boundaries of the property of the owner requesting this increase or restricted to flood storage areas shown on a recorded plat. Sec. 9.3.7. Streets in Floodprone Areas A. All streets in floodprone areas shall be designed and constructed to provide a minimum of 2 feet of vertical freeboard, as measured from the predicted 10 year flood peak water surface elevation to the low point of the top of curb or edge of pavement for streets without curbs. The following are exceptions to this standard: 1. Those portions of streets within allowable vertical and horizontal controls which act as a transition to existing streets; or 2. When the City Council finds that the public benefit derived from the construction of the thoroughfare or collector street would be better served if these standards were varied. 3. All thoroughfares in floodprone areas shall be designed and constructed so as not to be overtopped during the predicted 50 year storm. All other streets in floodprone areas shall be designed and constructed so as not to be overtopped during the predicted 25-year storm. B. For any street in floodprone areas, any proposed increase above floodway levels specified in the Flood Insurance Study, City of Raleigh, Federal Emergency Management Agency, latest publication may be allowed, provided that the change is approved by the Federal Insurance Administration. C. Any proposed street or driveway, bridge or culvert associated with a street or driveway (including fill), located in the floodprone area must be accompanied by a sealed written statement by a registered professional engineer licensed in North Carolina certifying that such structure is designed and constructed in accordance with this section and shall specify which provision applies. D. Outside of regulated discharge floodplain areas, the maximum depth of any overtopping flow during the predicted 100 year flood shall not exceed 1 foot. The downstream slope of the roadway section shall be protected from erosion due to the overtopping flow. Streets located within regulated discharge floodplain areas must be located at or above the 100 year flood elevation, consistent with the regulations of Sec. 9.3.5.A. Sec. 9.3.8. Warning & Disclaimer of Liability A. The degree of flood protection required by this Article is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur on rare occasions. Flood heights may be increased by man-made or natural causes. B. This Article does not imply that areas outside the boundaries of floodprone areas or land uses permitted within such areas will be free from flooding or flood damages. C. This Article shall not create liability on the part of the City or by any officer or employee for any flood damages that result from reliance on this Article or any administrative decision lawfully made. CHAPTER 9. ​NATURAL RESOURCE PROTECTION | Article 9.3. ​Floodprone Area Regulations Sec. 9.3.7. Streets in Floodprone Areas

RkJQdWJsaXNoZXIy NjM1NA==