§ 13-82. Procedures and development standards for floodway areas

(a) Review procedures. Pursuant to FEMA's National Flood Insurance Program regulations, the floodplain administrator shall review projects proposed in areas subject to the floodway areas district regulations to determine compliance with the provisions of this article. Specific responsibilities shall include, but not be limited to:

(1) Require permits for all proposed development within Zone A on the city's FIRM;

(2) Review proposed development to assure that all necessary permits have been received from those governmental agencies from which approval is required by federal or state law, including Section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 U.S.C. 1334;

(3) Review all permit applications to determine whether proposed building sites will be reasonably safe from flooding. If a proposed building site is in a flood-prone area, all new construction and substantial improvements shall (a) 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, (b) be constructed with materials resistant to flood damage, (c) be constructed by methods and practices that minimize flood damages, and (d) 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;

(4) Review subdivision proposals and other proposed new development to determine whether such proposals will be reasonably safe from flooding. If a subdivision proposal or other proposed new development is in a flood-prone area, any such proposals shall be reviewed to assure that (a) all such proposals are consistent with the need to minimize flood damage within the flood-prone area, (b) all public utilities and facilities, such as sewer, gas, electrical, and water systems are located and constructed to minimize or eliminate flood damage, and (c) adequate drainage is provided to reduce exposure to flood hazards;

(5) Require within flood-prone areas new and replacement water supply systems to be designed to minimize or eliminate infiltration of flood waters into the systems;

(6) Require that all new subdivision proposals and other proposed new developments (including proposals for subdivisions greater than fifty (50) lots or five (5) acres whichever is the lesser), include within such proposals base flood elevation data.

(b) Submittal requirements. All development, subdivision, structure and substantial improvement proposals shall include submittal of detailed drainage studies and plans drawn to scale showing the nature, location, dimensions and elevation of the area in question, and all existing or proposed structures, fill, storage of materials, drainage facilities and their locations. Specifically, the following information is required:

(1) Proposed elevation in relation to mean sea level, of the lowest floor (including basement) of all structures; in Zone AO and Zone AH, elevation of existing and proposed elevation of lowest floor of all structures.

(2) Proposed elevation in relation to mean sea level to which any structure will be floodproofed.

(3) Certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet the floodproofing criteria contained in this article.

(4) Description of the extent to which any watercourse will be altered or relocated as a result of proposed development. The plans, floor height information, and certifications shall be maintained on file by the development services department for flood insurance reference purposes.

(c) Alteration or relocation of watercourse. The floodplain administrator shall notify adjacent communities and the state department of water resources prior to approval of any project which would alter or relocate a watercourse having an effect on the flood hazard areas shown on the flood insurance rate maps and submit evidence of such notification to the appropriate federal agency. Any approval action for such project shall require that maintenance is provided within the altered or relocated portion of a watercourse so that the flood-carrying capacity of the watercourse is not diminished.

(d) Standards of construction. In all areas of special flood hazards, the following standards are required:

(1) All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure.

(2) All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage using methods and practices that minimize flood damage.

(3) New construction and substantial improvement of any structure shall have the lowest floor, including basement, elevated to or above the base flood elevation. Nonresidential structures may meet the standards in subsection (d)(5). Upon completion of the structure, the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor and provided to the development services department.

(4) New construction and substantial improvement of any structure in Zone AO and Zone AH shall have the lowest floor, including basement, elevated to or above the depth number specified on the FIRM. If there is no depth number on the FIRM, the lowest floor, including basement, shall be elevated at least two (2) feet above the highest adjacent grade. Nonresidential structures may meet the standards in subsection (d)(5). Upon completion of the structure, a registered professional engineer shall certify that the elevation of the structure meets this standard and such certification shall be provided to the development services department.

(5) Nonresidential construction shall either be elevated in conformance with subsections (d)(3) or (d)(4) or, together with attendant utility and sanitary facilities:

a. Be floodproofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of flood water.

b. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects on buoyancy; and

c. Be certified by a registered professional engineer or architect that the standards of this subsection are satisfied. The certifications shall be provided to the development services department.

(6) For all new construction and substantial improvements, 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 must 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 (1) foot above grade.

c. Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.

d. Within Zones AH and AO, adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures are required.

(e) Standards for utilities.

(1) All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from systems into floodwaters.

(2) Onsite waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

(3) Electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities shall be designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.

(f) Standards for subdivisions.

(1) All preliminary subdivision proposals shall identify the flood hazard area and the elevation of the base flood.

(2) All final subdivision plans will provide the elevation of proposed structure(s) and pads. If the site is filled above the base flood, the final pad elevation shall be certified by a registered professional engineer or surveyor and such certification shall be provided to the development services department.

(3) All subdivision proposals shall be consistent with the need to minimize flood damage.

(4) All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.

(5) All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage.

(g) Construction standards for manufactured homes and manufactured home parks and subdivisions.

(1) All manufactured homes and additions to manufactured homes shall be anchored to resist flotation, collapse, or lateral movement.

(2) For newly placed manufactured homes, new manufactured home parks or subdivisions, expansions to existing manufactured home parks or subdivisions, and repair, reconstruction, or improvements to existing manufactured home parks or subdivisions that equal fifty (50) per cent or greater of the value of the streets, utilities, and pads, (before the repair, reconstruction, or improvements commenced), the following standards shall apply:

a. Adequate surface drainage and access for a hauler shall be provided.

b. All manufactured homes shall be placed on pads or lots elevated on compacted fill or on pilings so that the lowest floor of the manufactured home is at or above the base flood level. If elevated on pilings, the following standards shall also apply:

i. The lots or pads shall be large enough to accommodate steps;

ii. The pilings shall be placed in stable soil no more than ten (10) feet apart; and

iii. Reinforcement shall be provided for pilings more than six (6) feet above ground level.

(3) Written certification of compliance with the standards contained in this section shall be provided by the installer of the manufactured home, the developer of the manufactured home park of subdivision, or the state agency responsible for regulating placement. The certification shall be maintained on file by the development services department for flood insurance purposes.

(4) No manufactured home shall be placed in a floodway area.

(h) Findings.

(1) Application for a permit may be denied where the floodplain administrator is unable to find that:

a. The development will not produce a significant risk to human life in the event of the design flood;

b. The development is designed and sited so as to offer minimal obstruction to the flow of floodwater; and

c. The development will not create a potential hazard or otherwise adversely affect property because of diversions, increased heights or velocities of floodwaters or because of increased debris or otherwise adversely affect the safety, use or stability of any public way, drainage channel or adjacent property during a flood condition.

(2) Applicants for permits as provided for in this article shall be required to submit studies, plans or other evidence prepared by a registered professional engineer or architect to support the required findings necessary for approval of the permit.

(Ord. No. 97-11, § 2, 5-5-97; Ord. No. 04-1, § 1, 1-20-04 ; Ord. No. 06-20, §§ 1h.—j., 9-19-06 )