Specific Standards for Riverine Zones

Specific Standards for Riverine Zones. In all areas of special flood hazard designated on the community’s FIRM, where base flood elevation data have been provided (excluding CHHA and Coastal AE Zone), as set forth in Part 208, Rule 3.1 & 3.2, the following provisions, in addition to the standards of Part 208, Rule 5.1, are required: (1) Residential Construction. New construction and substantial improvement of any residential building (including manufactured home) shall have the lowest floor, including 3986829.1/00520.00006 basement, elevated to no lower than 18 inches the base flood elevation. Should solid foundation perimeter walls be used to elevate a structure, flood openings sufficient to automatically equalize hydrostatic flood forces on exterior walls of enclosures that are subject to flooding, shall be provided in accordance with standards of Part 208, Rule 5.1. New development proposals will be designed, to the maximum extent practicable, so residential building sites, walkways, driveways, and roadways are located at natural grade with elevation not less than the base flood elevation and with evacuation routes leading directly out of the special flood hazard area. (2) Non-Residential Construction. New construction and substantial improvement of any commercial, industrial, or non-residential building (including manufactured building) shall have the lowest floor, including basement, elevated to no lower than 18 inches the base flood elevation. Buildings located in all A Zones may, together with attendant utility and sanitary facilities, be floodproofed in lieu of being elevated provided that all areas of the building below the base flood elevation (plus a minimum of 18 inches of freeboard are water tight with walls substantially impermeable to the passage of water, and use structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. Dry floodproofing is allowed only where flood velocities are less than or equal to five feet per second. A registered professional engineer or architect shall certify that the standards of this subsection are satisfied. A Flood Emergency Operation Plan and an Inspection and Maintenance Plan must be provided by the design professional for the building. Such certification shall be provided to the Floodplain Administrator. New development proposals will be designed, to the maximum extent practicable, so non-residential building sites, walkways, driveways, and roadways are located at natural grade with elevation not less than the base flood elevation and with evacuation routes leading directly out of the special flood hazard area. (3) In special flood hazard areas with base flood elevations (AE Zones) but without floodways, no encroachments, including fill material or structures, shall be permitted unless certification by a registered professional engineer is provided demonstrating that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the community. The engineering certification must be supported by technical data that conforms to standard hydraulic engineering principles. (4) Enclosures. New construction and substantial improvements that include fully enclosed areas formed by foundation and other exterior walls below the lowest floor shall be designed to preclude finished living space and designed to allow for the entry and exit of floodwaters to automatically equalize hydrostatic flood forces on exterior walls. . Enclosed areas including crawl spaces, shall be used solely for parking of vehicles, building access, and storage. 3986829.1/00520.00006 a.) Designs for complying with this requirement must either be certified by a professional engineer or architect or meet or exceed the following criteria: (i) Provide a minimum of two openings, on different sides of each enclosed area; if a structure has more than one enclosed area below the base flood elevation, each shall have openings on exterior walls; (ii) The total net area of all openings shall be at least one square inch for each square foot of enclosed area, or the openings shall be designed and the construction documents shall include a statement that the design and installation will provide for equalization of hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwaters; (iii) The bottom of all openings shall be no higher than one foot above interior grade (which must be equal to in elevation or higher than the exterior grade); (iv) Openings shall allow the passage of a three inch sphere. (v) Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwaters in both directions and automatically equalize hydrostatic flood loads on exterior walls, and; b.) Access to the enclosed area shall be minimum necessary to allow for parking of vehicles (garage door) or limited storage of maintenance equipment used in connection with the premises (standard exterior door) or entry to the living area (stairway or elevator); and c.) The interior portion of such enclosed area shall not be finished or partitioned into separate rooms. d.) Property owners shall be required to execute a flood openings/venting affidavit acknowledging that all openings will be maintained as flood vents, and that the elimination or alteration of the openings in any way will violate the requirements of Part 208, Rule 5.2. Periodic inspections will be conducted by the Floodplain Administrator to ensure compliance. (5) Detached storage buildings, sheds, or other like accessory improvements, excluding detached garages, carports, and boat houses, shall solely be used for parking of vehicles and storage. Such storage space shall not be used for human habitation and shall be limited to storage of items that can withstand exposure to the 3986829.1/00520.00006 elements and have low flood damage potential. The storage space shall be constructed of flood resistant or breakaway materials, and equipment and service utilities, such as electrical outlets, shall be limited to essential lighting and other incidental uses, and must be elevated or floodproofed. Flood openings in accordance with the standards of Part 208, Rule 5.2 (4) shall also be required. These accessory structures shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters. Accessory improvements and other appurtenant structures shall be firmly anchored to prevent flotation that may result in damage to other structures. (6) Property owners shall be required to execute and record with the structure’s deed a non-conversion agreement declaring that the area below the lowest floor of the structure or the detached accessory building shall not be improved, finished or otherwise converted; the community will have the right to inspect the enclosed area. (7) Standards for Manufactured Homes and Recreational Vehicles. a.) All manufactured homes placed, or substantially improved, on individual lots or parcels, in existing manufactured home parks or subdivisions, in expansions to existing manufactured home parks or subdivisions, in new manufactured home parks or subdivisions or in substantially improved manufactured home parks or subdivisions, must meet all the requirements for new construction, including elevation and anchoring and the flood openings requirements of Part 208, Rule 5.2 (4). Manufactured homes must be: (i) Elevated on a permanent foundation to have its lowest floor elevated to no lower than 18 inches above the base flood elevation, and; (ii) Securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement. b.) All recreational vehicles placed on sites must either: (i.) Be on site for fewer than sixty (60) consecutive days and shall leave the site for at least seven consecutive days and obtain a new permit before returning to the same site, (ii.) Be fully licensed and ready for highway use, or (iii.) Must meet all the requirements for new construction, including anchoring and elevation requirements of this Part 208, Rule 5.2 (a) or Rule 5.8 (b) (i) above. 3986829.1/00520.00006 A recreational vehicle is ready for highway use if it is licensed and insured in accordance with the state of Mississippi motor vehicle regulations, is on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices and has no permanently attached additions. (8) Floodways. Located within areas of special flood hazard adopted by reference in Part 208, Rule 3.1, are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles and has erosion potential, the following provisions shall apply: a.) Prohibit encroachments, including fill, new construction, substantial improvements, and other developments unless certification (with supporting technical data) by a registered professional engineer is provided demonstrating that encroachments shall not result in any increase in flood levels during occurrence of the base flood discharge; b.) If Part 208, Rule 5.2 (8) (a) above is satisfied, all new construction and substantial improvements shall comply with all applicable flood damage prevention standards of Rule 5. c.) Prohibit the placement of manufactured homes (mobile homes), except in an existing manufactured homes (mobile homes) park or subdivision. A replacement manufactured home may be placed on a lot in an existing manufactured home park or subdivision provided the anchoring standards of Part 208, Rule 5.1 (2), and the standards of Rule 5.2 (1) through (3) and the encroachment standards of this Rule 5.2 (8) (a), are met.