Located within areas of special flood hazard are areas designated as floodways. Since the floodway is in an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles and erosion potential, the following provisions apply:
(A) Prohibit encroachments, including fill, new construction, substantial improvements and other development within the adopted regulatory floodway unless certification, with supporting technical data, by a Connecticut registered professional engineer is provided demonstrating, through hydrologic and hydraulic analyses performed in accordance with standard engineering practice, that encroachments shall not result in any (0.00 feet) increase in flood levels during occurrence of the base flood discharge published by FEMA. Buildings and structures meeting the standard above and located in whole or in part in the floodway shall be designed and constructed in accordance with ASCE 24. Fences in the floodway must be aligned with the flow and be of an open design.
(B) Standards for Development in Areas of Shallow Flooding (Zones AO and AH). Located within the Special Flood Hazard Areas (SFHA) are areas designated as shallow flooding areas (AO and AH Zones). These areas have flood hazards associated with base flood depths of one to three feet where a clearly defined channel does not exist and where the path of flooding is unpredictable and indeterminate. In AO and AH zones, the following provisions apply:
(C) For residential structures, all new construction, substantial improvements and repair to structures that have sustained substantial damage shall have the lowest floor, including basement, elevated above the highest adjacent grade at least as high as one foot above the depth number specified on the Flood Insurance Rate Map (FIRM). If no depth number is specified, the lowest floor, including basement, shall be elevated at least three feet above the highest adjacent grade.
(D) For non-residential structures, all new construction, substantial improvements and repair to structures that have sustained substantial damage shall:
(1) Have the lowest floor, including basement, elevated above the highest adjacent grade at least as high as one foot above the depth number specified on the Flood Insurance Rate Map (FIRM). If no depth number is specified, the lowest floor, including basement, shall be elevated at least three feet above the highest adjacent grade; or
(2) Together with attendant utility and sanitary facilities be completely floodproofed to above the highest adjacent grade at least as high as one foot above the depth number specified on the FIRM, or if no depth number is specified at least three feet above the highest adjacent grade, so that any space below that level is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. Designs for complying with this requirement must either be certified by a registered professional engineer or architect.
(E) On-site drainage for all proposed structures in AO and AH Zones located on slopes shall provide adequate drainage paths to guide flood waters around and away from such structures.
(F) Fully enclosed areas below the lowest floor in AO and AH Zones must comply with the provisions of § 151.66(C) for hydraulic vents.
(Ord. passed 6-22-1981; Ord. passed 12-19-1988; Ord. passed 5-31-2022)
Editor’s note:
TM Volume 14, page 122; TM Volume 16, page 262, Amended