All new construction and substantial improvements (including manufactured homes subject to municipal regulation) located on lands zoned "Flood Plain" shall be:
(a) Use Regulations. All uses not otherwise prohibited in this section or any other applicable land use regulation adopted by the City are allowed provided they meet the provisions of these regulations.
(b) Water and Wastewater Systems. The following standards apply to all water supply, sanitary sewerage and waste disposal systems in the absence of any more restrictive standard provided under the Ohio Revised Code or applicable state rules:
(1) All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system;
(2) New and replacement sanitary sewerage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters; and,
(3) On-site waste disposal systems shall be located to avoid impairment to or contamination from them during flooding.
(c) Subdivisions and other New Developments.
(1) All subdivision proposals and all other proposed new development shall be consistent with the need to minimize flood damage and are subject to all applicable standards in these regulations;
(2) All subdivision proposals and all other proposed new development shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage;
(3) All subdivision proposals and all other proposed new development shall have adequate drainage provided to reduce exposure to flood damage;
(4) In all areas of special flood hazard where base flood elevation data are not available, the applicant shall provide a hydrologic and hydraulic engineering analysis that generates base flood elevations for all subdivision proposals and other proposed developments containing at least fifty lots or five acres, whichever is less; and
(d) Residential Structures. The requirements of this section apply to new construction of residential structures and to substantial improvements of residential structures in Zones A, A 1-30, AE, AO and AH when designated on the community's effective FIRM, and when designated on a preliminary or final FIRM issued by FEMA under the circumstances provided in Section 1333.24.
(1) New construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads including the effects of buoyancy. Where a structure, including its foundation members, is elevated on fill to or above the base flood elevation, the requirements for anchoring and construction materials resistant to flood damage are satisfied.
(2) New construction and substantial improvements shall be constructed with methods and materials resistant to flood damage.
(3) New construction and substantial improvements shall be constructed with electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities that are designed and/or elevated so as to prevent water from entering or accumulating within the components during conditions of flooding.
(4) New construction and substantial improvement of any residential structure, including manufactured homes, shall have the lowest floor, including basement, elevated to or above the flood protection elevation. In Zone AO areas with no elevations specified, the structure shall have the lowest floor, including basement, elevated at least two feet above the highest adjacent natural grade.
(5) New construction and substantial improvements, including manufactured homes, that do not have basements and that are elevated to the flood protection elevation using pilings, columns, posts, or solid foundation perimeter walls with openings to allow the automatic equalization of hydrostatic pressure may have an enclosure below the lowest floor provided the enclosure meets the following standards:
A. Be used only for the parking of vehicles, building access, or storage;
B. Be designed and certified by a registered professional engineer or architect to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters; or
C. Have a minimum of two openings on different walls having a total net area not less than one square inch for every square foot of enclosed area, and the bottom of all such openings being no higher than one foot above grade. The openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
(6) Manufactured homes shall be affixed to a permanent foundation and anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. Methods of anchoring may include, but not be limited to, use of over-the-top or frame ties to ground anchors.
(7) Repair or rehabilitation of historic structures upon a determination that the proposed repair or rehabilitation will not preclude the structure's continued designation as a historic structure and is the minimum necessary to preserve the historic character and design of the structure, shall be exempt from the development standards above.
(8) In AO and AH Zones, new construction and substantial improvement shall have adequate drainage paths around structures on slopes to guide floodwaters around and away from the structure.
(e) Nonresidential Structures. The requirements of this section apply to new construction and to substantial improvements of nonresidential structures in zones A. A 1-30, AE, AO and AH when designated on the community's effective FIRM, and when designated on a preliminary or final FIRM issued by FEMA under the circumstances provided in Section 1333.24.
(1) New construction and substantial improvement of any commercial. industrial or other nonresidential structure shall meet the requirements of 1333.15(d)1-3 & 5-7;
(2) New construction and substantial improvement of any commercial. industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated to or above the level of the flood protection elevation: or, together with attendant utility and sanitary facilities, shall meet the following standards:
A. Be dry floodproofed so that the structure is watertight with walls substantially impermeable to the passage of water to the level of the flood protection elevation;
B. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
C. Be certified by a registered professional engineer or architect, through the use of a Federal Emergency Management Agency Floodproofing Certificate, that the design and methods of construction are in accordance with 1333.15(e)(2)A. and B.; and,
D. In Zone AO areas with no elevations specified, the structure shall have the lowest floor, including basement, elevated at least two feet above the highest adjacent natural grade.
(f) Accessory Structures. Structures that are 600 square feet or less which are used for parking and storage only are exempt from elevation or dry floodproofing standards within zones A, A1-30, AE, AO, and AH designated on the community's FIRM. Such structures must meet the following standards:
(1) They shall not be used for human habitation;
(2) They shall be constructed of flood resistant materials;
(3) They shall be constructed and placed on the lot to offer the minimum resistance to the flow of floodwaters;
(4) They shall be firmly anchored to prevent flotation;
(5) Service facilities such as electrical and heating equipment shall be elevated or floodproofed to or above the level of the flood protection elevation; and
(g) Recreational Vehicles. Recreational vehicles on sites within zones A, A 1-30, AE. AO, or AH must meet at least one of the following standards:
(1) They shall not be located on sites in special flood hazard areas for more than 180 days;
(2) They must be fully licensed and ready for highway use; or
(h) Gas or Liquid Storage Tanks. Within zone A A1-30, AE, AO, or AH, new or substantially improved above ground or liquid storage tanks shall be anchored to prevent flotation or lateral movement resulting from hydrodynamic and hydrostatic loads.
(i) Assurance of Flood Carrying Capacity. Pursuant to the purpose and methods or reducing flood damage stated in these regulations, the following additional standards are adopted to assure that the reduction of the flood carrying capacity of watercourses is minimized:
(1) Development in Floodways.
A. In floodway areas. development shall cause no increase in flood levels during the occurrence of the base flood discharge. Prior to issuance of a floodplain development permit, the applicant must submit a hydrologic and hydraulic analysis, conducted by a registered professional engineer, demonstrating that the proposed development would not result in any increase in the base flood elevation; or
B. Development in floodway areas causing increases in the base flood elevation may be permitted provided all of the following are completed by the applicant:
2. An evaluation of alternatives. which would not result in increased base flood elevations and an explanation why these alternatives are not feasible;
3. Certification that no structures are located in areas that would be impacted by the increased base flood elevation;
4. Documentation of individual legal notices by certified mail, return receipt requested, to all impacted property owners within and outside the community, explaining the impact of the proposed action on their property; and
5. Concurrence of the City Administrator of the City of Defiance and the Chief Executive Officer of any other communities impacted by the proposed actions.
(2) Development in Riverine Areas with Base Flood Elevations but No Floodways.
A. In riverine special flood hazard areas identified by FEMA where base flood elevation data are provided but no floodways have been designated, the cumulative effect of any proposed development, when combined with all other existing and anticipated development, shall not increase the base flood elevation more than 1.0 (one) foot at any point. Prior to issuance of a floodplain development permit. the applicant must submit a hydrologic and hydraulic analysis, conducted by a registered professional engineer, demonstrating that this standard has been met; or
B. Development in riverine special flood hazard areas identified by FEMA where base flood elevation data are provided but no floodways have been designated causing more than one foot increase in the base flood elevation may be permitted provided all of the following are completed by the applicant:
1. An evaluation of alternatives which would result in an increase of one foot or less of the base flood elevation and an explanation why these alternatives are not feasible;
(3) Alterations of a Watercourse. For the purpose of these regulations, a watercourse is altered when any change occurs within its banks. The extent of the banks shall be established by a field determination of the “bankfull stage". The field determination of “bankfull stage" shall be based on methods presented in Chapter 7 of the USDA Forest Service General Technical Report RM-245, Stream Channel Reference Sites: An Illustrated Guide to Field Technique or other applicable publication available from a Federal, State or other authoritative source. For all proposed developments that alter a watercourse, the following standards apply:
A. The bankfull flood carrying capacity of the altered or relocated portion of the watercourse shall not be diminished. Prior to the issuance of a floodplain development permit, the applicant must submit a description of the extent to which any watercourse will be altered or relocated as a result of the proposed development, and certification by a registered professional engineer that the bankfull flood carrying capacity of the watercourse will not be diminished.
B. Adjacent communities, the US Army Corps of Engineers, and the Ohio Department of Natural Resources, Division of Water, must be notified prior to any alteration or relocation of a watercourse. Evidence of such notification must be submitted to the Federal Emergency Management Agency.
C. The applicant shall be responsible for providing the necessary maintenance for the altered or relocated portion of said watercourse so that the flood carrying capacity will not be diminished. The Floodplain Administrator may require the permit holder to enter into an agreement with the City of Defiance specifying the maintenance responsibilities. If an agreement is required, it shall be made a condition of the floodplain development permit.
D. The application shall meet the requirements to submit technical data in Section 1333.23(a)(1)D. when an alteration of a watercourse results in the relocation or elimination of the special flood hazard area, including the placement of culverts.
(Ord. 8289. Passed 3-2-21.)