A. General Standards: In all areas of special flood hazard the following provisions are required for all new construction and substantial improvements:
1. All new construction or substantial improvements shall be designed (or modified) and adequately anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;
2. All new construction or substantial improvements shall be constructed by methods and practices that minimize flood damage;
3. All new construction or substantial improvements shall be constructed with materials resistant to flood damage;
4. All new construction or substantial improvements shall be constructed with electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
5. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system;
6. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from the systems into floodwaters; and
7. On site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
8. Compensatory storage shall be provided if filling or development diminishes the flood storage capacity of any regulatory floodplain.
9. New construction, substantial improvements or other development (including fill) shall not be approved if it:
a. Adversely affects the capacity of channels or floodways of any watercourse herein identified as in the area of special flood hazard to convey the regulatory flood.
b. Would measurably increase flood flows or flood heights or increase flood damage upon off site properties during the occurrence of the regulatory flood.
c. Would individually, or combined with all other existing and anticipated development, expose additional upstream, downstream or adjacent properties to adverse flood effects that would otherwise not be exposed to such effects due to the regulatory flood.
d. Increases velocities or volumes of floodwaters to the extent that significant erosion of floodplain soils would occur either on the subject property or on some other property upstream or downstream.
e. Does not provide compensatory storage for any measurable loss of flood storage capacity.
B. Specific Standards: In all areas of special flood hazards the following provisions are required:
1. Critical Facilities: New construction and substantial improvement of any critical facility shall have the lowest floor (including basement) and all utilities, elevated at a minimum of one foot (1') above the 0.2 percent flood (500-year) elevation. A registered professional engineer or land surveyor shall submit a certification to the floodplain administrator that this standard is satisfied.
2. Residential Construction: New construction and substantial improvement of any residential structure shall have the lowest floor (including basement) and all utilities, elevated at a minimum of one foot (1') above the base flood elevation. A registered professional engineer, architect, or land surveyor shall submit a certification to the floodplain administrator that this standard is satisfied.
3. Nonresidential Construction: New construction and substantial improvements of any commercial, industrial or other nonresidential structure shall have the lowest floor (including basement) and all utilities elevated at a minimum of one foot (1') above the base flood level. A registered professional engineer or land surveyor shall submit a certification to the floodplain administrator that this standard is satisfied. There is certain nonresidential construction not intended for the sheltering of persons that are for purposes of drainage, transportation, certain storage facilities, and utilities that by nature of their purpose cannot be elevated a minimum of one foot (1') above the base flood level; those certain structures shall be constructed of flood damage resistant materials to one foot (1') above the base flood elevation.
4. Enclosures: New construction and substantial improvements, with fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria:
a. A minimum of two (2) openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided.
b. The bottom of all openings shall be no higher than one foot (1') above grade.
c. Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
5. Manufactured Homes:
a. Require that all manufactured homes to be placed within zone A on a community's FHBM or FIRM shall be installed using methods and practices that minimize flood damage and have the bottom of the I-beam elevated at a minimum of one foot (1') above the base flood elevation. For the purposes of this requirement, manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not limited to, use of over the top or frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces.
b. Require that manufactured homes that are placed or substantially improved within zones A1-30, AH, and AE on the community's FIRM on sites: 1) outside of a manufactured home park or subdivision, 2) in a new manufactured home park or subdivision, 3) in an expansion to an existing manufactured home park or subdivision, or 4) in an existing manufactured home park or subdivision on which a manufactured home has incurred "substantial damage" as a result of a flood, be elevated on a permanent foundation such that the bottom of the I-beam of the manufactured home and all utilities shall be elevated at a minimum of one foot (1') above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement. Also, the home shall be installed by a licensed installer and comply with state law.
c. Require that manufactured homes be placed or substantially improved on sites in an existing manufactured home park or subdivision with zones A1-30, AH and AE on the community's FIRM that are not subject to the provisions of subsection B4 of this section be elevated so that the bottom of the I-beam of the manufactured home and all utilities a minimum one foot (1') above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement supporting the manufactured home chassis and also installed by a licensed installer that complies with state law.
6. Recreational Vehicles: Require that recreational vehicles placed on sites within zones A1-30, AH, and AE on the community's FIRM either:
a. Be on the site for fewer than one hundred eighty (180) consecutive days,
b. Be fully licensed and ready for highway use, or
c. Meet the permit requirements of subsections 10-10-4C1 and C2 of this chapter, and the elevation and anchoring requirements for "manufactured homes" in subsection B5 of this section. A recreational vehicle is ready for highway use if it 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.
7. Accessory Structure:
a. Structure is low valued and represents a minimal investment.
b. Structure shall be small and not exceed six hundred (600) square feet in size.
c. Structure shall be unfinished on the interior.
d. Structure can be used only for parking and limited storage.
e. Structure shall not be used for human habitation (including work, sleeping, living, cooking, or restroom areas).
f. Service facilities such as electrical and heating equipment shall be elevated at a minimum of one foot (1') above the BFE.
g. Structure is constructed and placed on building site so as to offer the minimum resistance to the flow of floodwaters.
h. Structure is designed to have low flood damage potential, i.e., constructed with flood resistant materials.
i. Structure is firmly anchored to prevent flotation, collapse, and lateral movement.
j. Floodway requirements must be met in the construction of the structure.
k. Openings to relieve hydrostatic pressure during a flood shall be provided below the BFE.
l. Structure is to be located so as not to cause damage to adjacent and nearby structures.
C. Standards For Subdivision Proposals:
1. All subdivision proposals including the placement of manufactured home parks and subdivisions shall be consistent with subsections 10-10-1B, C, and D of this chapter.
2. All proposals for the development of subdivisions including the placement of manufactured home parks and subdivisions shall meet development permit requirements of subsections 10-10-3C and 10-10-4C of this chapter and the provisions of this section.
3. Regulatory floodplain elevation data and floodplain delineation shall be generated and clearly shown for subdivision proposals and other proposed development including the placement of manufactured home parks and subdivisions which are greater than fifty (50) lots or five (5) acres, whichever is lesser, if not otherwise provided pursuant to subsection 10-10-3B or 10-10-4B8 of this chapter.
4. All subdivision proposals including the placement of manufactured home parks and subdivisions shall have adequate drainage provided to reduce exposure to flood hazards and shall comply with title 12, chapter 8 of this code.
5. All subdivision proposals including the placement of manufactured home parks and subdivisions shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize or eliminate flood damage.
D. Standards For Areas Of Shallow Flooding (AO/AH Zones): Located within the areas of special flood hazard established in subsection 10-10-3B of this chapter, are areas designated as shallow flooding. These areas have special flood hazards associated with base flood depths of one to three feet (3') where a clearly defined channel does not exist and where the path of flooding is unpredictable and where velocity flows may be evident. Such flooding is characterized by ponding or sheet flow; therefore, the following provisions apply:
1. All new construction and substantial improvements of residential structures shall have the lowest floor (including basement) elevated at a minimum of one foot (1') above the highest adjacent grade at least as high as the depth number specified in feet on the community's FIRM (at least 2 feet if no depth number is specified).
2. All new construction and substantial improvements of nonresidential structures shall have the lowest floor (including basement) elevated at a minimum of one foot (1') above the highest adjacent grade and at least as high as the depth number specified in feet on the community's FIRM (at least 2 feet if no depth number is specified).
3. A registered professional engineer or architect shall submit a certification to the floodplain administrator that the standards of this section are satisfied.
4. Require within zones AH or AO adequate drainage paths around structures on slopes, to guide floodwaters around and away from proposed structures.
5. The foregoing requirements of this subsection are minimal requirements and shall not relieve any new construction or substantial improvements from meeting and complying with additional requirements and provisions of this chapter.
E. Floodways: Located within areas of special flood hazard established in subsection 10-10-3B of this chapter, are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters that carry debris, potential projectiles and erosion potential, the following provisions shall apply:
1. Encroachments are prohibited, including fill, new construction, substantial improvements and other development within the adopted regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels within the community during the occurrence of the base flood discharge.
2. If subsection E1 of this section is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section.
3. Under the provisions of 44 CFR chapter 1, section 65.12 of the national flood insurance regulations, a community may permit encroachments within the adopted regulatory floodway that would result in an increase in base flood elevations, provided that the community complies with all of 44 CFR chapter 1, section 65.12. (Ord. 6103, 7-27-2009)