Unified Development Ordinance, 4th supplement, September 2017

Part 10A: Unified Development Ordinance City of Raleigh, North Carolina 9 – 25 Effective Date: September 01, 2013 Supp. No. 4 Article 9.3. Floodprone Area Regulations Sec. 9.3.1. Floodprone Areas A. Mapped Floodprone Areas 1. The mapped floodprone areas are divided into 3 primary areas: a. Floodway areas; b. Floodway fringe areas; and c. Future conditions flood hazard areas. 2. Floodprone areas are identified under the CooperatingTechnical State (CTS) agreement between the State of North Carolina and the Federal Emergency Management Agency (FEMA) in its flood insurance study and accompanying flood insurance rate maps, flood hazard soil maps and drainage basin study maps. These maps together with all explanatory matter attached to them are adopted and incorporated by reference into this UDO. 3. Floodprone area regulations are superimposed on the zoning districts established in Article 1.3. Zoning Districts and the requirements of this Article apply in addition to any base zoning requirement. 4. The City Council may, on its own motion or upon petition after public notice and hearing amend, supplement, change, modify or repeal the regulations and the flood hazard boundary maps and the delineated flood storage area maps. Amendment to flood insurance rate maps originating from the Federal Insurance Administration shall not become official until a letter stating approval from the Federal Insurance Administration is received by the City. B. Additional Floodprone Areas Floodprone areas adjoining creeks, streams, tributaries and watercourses not defined on the flood hazard boundary maps include the following. 1. Watercourses that drain 1 square mile or more, lying 5 vertical feet from the outer limit of the flood hazard soils or the made land which spans flood hazard soils lying along such watercourses; and 2. Watercourses draining less than 1 square mile are defined as those areas lying within 2 additional feet vertical from the outer limits of the flood hazard soils or made land which traverses such soils. Sec. 9.3.2. Flood Hazard Soils A. Flood hazard soils are shown on aerial photographic base maps prepared by the U.S. Soil Conservation Service and the North Carolina Agricultural Experiment Station from a soil survey. B. The outer limits of flood hazard soils may be specifically described by metes and bounds or other means from detailed surveys by owners of property on which they lie, provided the accuracy of such description is reviewed and approved by the PublicWorks Director and that maps or plats of such description are filed with the Clerk of the Superior Court and with the Register of Deeds ofWake County. C. Upon approval by the PublicWorks Director, drainage basin study maps may supersede flood hazard soil maps. Floodprone areas and flood elevation data shall be obtained from the most current drainage basin study maps or the flood studies. Sec. 9.3.3. Rules for Interpretation of Boundaries A. The boundaries of floodprone areas shown on flood insurance rate maps shall be initially determined from the information obtained from the Corps of Engineers and presented in the flood insurance rate maps and the flood insurance study by FEMA. B. Floodprone boundaries shall be based on the engineering data that most accurately reflects actual field and hydrologic conditions. Field and hydraulic conditions shall prevail over mapped boundaries shown on flood insurance study profiles, flood hazard soils and drainage basin study maps. C. In areas between official cross-sections, floodprone area boundaries shall be determined by scaling distances on the flood insurance rate maps. Where interpretation of the lateral location of scaled distances is needed to determine the actual field location of these boundaries, the PublicWorks Director is directed to make the necessary interpretation and corrections of flood insurance rate maps applying the following: 1. The base flood elevation shall be the controlling factor in locating the outer limits of a floodway fringe or future conditions flood hazard area boundary; 2. Interpretations of floodway boundaries on flood insurance rate maps shall be based on the current procedures for interpreting floodways in accord with the FEMA guidelines; and Article 9.3. ​​Floodprone Area Regulations | CHAPTER 9. ​NATURAL RESOURCE PROTECTION Sec. 9.3.1. Floodprone Areas