§ 9.5.4. Flood Damage Reduction

A.

General Standards In all areas of special flood hazard and areas of future-conditions flood hazard the following provisions apply:

1.

New construction and substantial improvements of structures (residential or nonresidential), including manufactured homes, shall not be allowed within the limits of the future-conditions floodplain, unless all requirements of Sec. 9.5.3 have been met.

2.

New construction and substantial improvements shall be anchored to prevent flotation, collapse, and lateral movement of the structure.

3.

New construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.

4.

New construction and substantial improvements shall be constructed by methods and practices that minimize flood damage.

5.

Elevated building. All new construction and substantial improvements that include any fully enclosed area located below the lowest floor formed by foundation and other exterior walls are designed so as to be an unfinished or flood-resistant enclosure. The enclosure is designed to equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwater.

a.

Designs for complying with this requirement must either be certified by a licensed professional engineer or architect to meet or exceed the following minimum criteria:

i.

Provide a minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;

ii.

The bottom of all openings are no higher than one foot above grade; and

iii.

Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwater in both directions.

b.

So as not to violate the lowest floor criteria of this Division, the unfinished or flood-resistant enclosure shall only be used for parking of vehicles, limited storage of maintenance equipment used in connection with the premises, or entry to the elevated area; and

c.

The interior portion of such enclosed area shall not be finished or partitioned into separate rooms.

6.

All heating and air conditioning equipment and components (including ductwork), all electrical, ventilation, plumbing, and other service facilities are designed and/or located three feet above the base flood elevation or one foot above the future-conditions flood elevation, whichever is higher, so as to prevent water from entering or accumulating within the components during conditions of flooding;

7.

Manufactured homes are anchored to prevent flotation, collapse, and lateral movement. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors. This standard is in addition to and consistent with applicable state requirements for resisting wind forces;

8.

All proposed development shall include adequate drainage and stormwater management facilities per the requirements of the City to reduce exposure to flood hazards;

9.

New and replacement water supply systems are designed to minimize or eliminate infiltration of floodwaters into the system;

10.

New and replacement sanitary sewage systems are designed to minimize or eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters;

11.

On-site waste disposal systems are located and constructed to avoid impairment to, or contamination from such systems during flooding;

12.

Other public utilities such as gas and electric systems shall be located and constructed to avoid impairment to them, or public safety hazards from them during flooding;

13.

Any alteration, repair, reconstruction or improvement to a structure which is not compliant with the provisions of this Division is undertaken only if the nonconformity is not furthered, extended or replaced;

14.

If the proposed development is located in multiple flood zones or multiple base flood elevations cross the proposed site, the higher or more restrictive base flood elevation or future-condition elevation and development standards shall take precedence;

15.

When only a portion of a proposed structure is located within a flood zone or the future conditions floodplain, the entire structure shall meet the requirements of this Division; and

16.

Subdivision proposals and other proposed new development, including manufactured home parks or subdivisions, shall be reasonably safe from flooding:

a.

All such proposals shall be 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 shall be located and constructed to minimize or eliminate flood damage; and

c.

Adequate drainage shall be provided to reduce exposure to flood hazards.

B.

Building Standards for Structures and Buildings within the Future-Conditions Floodplain  

1.

Residential Buildings  

a.

New Construction New construction of principal residential structures shall not be allowed within the limits of the future-conditions floodplain.

b.

Substantial Improvements Substantial improvements of any principal residential structure shall have the lowest floor, including basement, elevated no lower than three feet above the base flood elevation or one foot above the future-conditions flood elevation, whichever is highest. Should solid foundation perimeter walls be used to elevate a structure, openings sufficient to automatically equalize the hydrostatic flood forces on exterior walls shall be provided in accordance with the standards of Sec. 9.5.4.A.

2.

Nonresidential Buildings  

a.

New Construction New construction of principal nonresidential structures shall not be allowed within the limits of the future-conditions floodplain unless all of the requirements of Sec. 9.5.3 are met.

If all of the requirements of Sec. 9.5.3 have been met, all new construction shall have the lowest floor, including basement, elevated no lower than one foot above the base flood elevation or at least as high as the future-conditions flood elevation, whichever is higher.

Should solid foundation perimeter walls be used to elevate the structure, openings sufficient to automatically equalize the hydrostatic flood forces on exterior walls shall be provided in accordance with the standards of Sec. 9.5.4.A.

New construction that has met all of the requirements of Sec. 9.5.3 may be floodproofed in lieu of elevation. The structure, together with attendant utility and sanitary facilities, must be designed to be watertight to one foot above the base flood elevation, or at least as high as the future-conditions flood elevation, whichever is higher, with walls substantially impermeable to the passage of water and structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. A licensed professional engineer or architect shall certify that the design and methods of construction are in accordance with accepted standards of practice for meeting the provisions above, and shall provide such certification to the Director using the FEMA floodproofing certificate along with the design and operation/maintenance plan.

b.

Substantial Improvements Substantial improvements of any principal nonresidential structure located in A1-30, AE, or AH zones may be authorized by the Director to be elevated or floodproofed.

Substantial improvements shall have the lowest floor, including basement, elevated no lower than one foot above the base flood elevation or at least as high as the future-conditions flood elevation, whichever is higher.

Should solid foundation perimeter walls be used to elevate the structure, openings sufficient to automatically equalize the hydrostatic flood forces on exterior walls shall be provided in accordance with the standards of Sec. 9.5.4.A.

Substantial improvements may be floodproofed in lieu of elevation. The structure, together with attendant utility and sanitary facilities, must be designed to be watertight to one foot above the base flood elevation, or at least as high as the future-conditions flood elevation, whichever is highest, with walls substantially impermeable to the passage of water, and structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. A licensed professional engineer or architect shall certify that the design and methods of construction are in accordance with accepted standards of practice for meeting the provisions above, and shall provide such certification to the Director using the FEMA floodproofing certificate along with the design and operation/maintenance plan.

c.

Accessory Structures and Facilities Accessory structures and facilities (i.e., barns, sheds, gazebos, detached garages, recreational facilities and other similar non-habitable structures and facilities) which meet the requirements of Sec. 9.5.3 and are permitted to be located within the limits of the future-conditions floodplain shall be constructed of flood-resistant materials and designed to provide adequate flood openings in accordance with Sec. 9.5.4.A and be anchored to prevent flotation, collapse, and lateral movement of the structure.

d.

Recreational Vehicles All recreational vehicles placed on sites must either:

i.

Be on the site for fewer than 180 consecutive days and be fully licensed and ready for highway use (a recreational vehicle is ready for highway use if it is licensed, on its wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached structures or additions); or

ii.

Meet all the requirements for residential buildings—substantial improvements set forth in Sec. 9.5.4.B.1.b, including the anchoring and elevation requirements.

e.

Manufactured Homes  

i.

New manufactured homes shall not be allowed to be placed within the limits of the future-conditions floodplain unless all of the requirements of Sec. 9.5.3 have been met, all new construction and substantial improvements shall have the lowest floor, including basement, elevated no lower than three feet above the base flood elevation or one foot above the future-conditions flood elevation, whichever is higher. Should solid foundation perimeter walls be used to elevate the structure, openings sufficient to automatically equalize the hydrostatic flood forces on exterior walls shall be provided in accordance with the standards of Sec. 9.5.4.A.

ii.

Manufactured homes placed and/or substantially improved in an existing manufactured home park or subdivision are elevated so that either: (a) The lowest floor of the manufactured home is elevated no lower than three feet above the level of the base flood elevation, or one foot above the future-conditions flood elevation, whichever is higher; or (b) The manufactured home chassis is elevated and supported by reinforced piers (or other foundation elements of at least an equivalent strength) of no less than 36 inches in height above grade.

iii.

All manufactured homes must be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement in accordance with the standards of Sec. 9.5.4.A.7.

C.

Building Standards for Structures and Buildings Authorized Adjacent to the Future-Conditions Floodplain  

1.

Residential Buildings For new construction of and substantial improvement to any principal residential building or manufactured home, the elevation of the lowest floor, including basement and access to the building, is at least three feet above the level of the highest base flood (100-year) elevation adjacent to the building or at least one foot above the future-conditions flood elevation, whichever is higher. Should solid foundation perimeter walls be used to elevate the structure, openings sufficient to automatically equalize the hydrostatic flood forces on exterior walls shall be provided in accordance with the standards of Sec. 9.5.4.

2.

Nonresidential Buildings For new construction of and substantial improvement to any principal nonresidential building, the elevation of the lowest floor, including basement and access to the building, is at least three feet above the level of the highest base flood elevation adjacent to the building or at least one foot above the future-conditions flood elevation, whichever is higher. Should solid foundation perimeter walls be used to elevate the structure, openings sufficient to automatically equalize the hydrostatic flood forces on exterior walls shall be provided in accordance with the standards of Sec. 9.5.4. Nonresidential buildings may be floodproofed in lieu of elevation.

D.

Building Standards for Residential Single-Lot Development on Streams without Established Base Flood Elevations and/or Floodway (A zones) For a residential single-lot development not part of a subdivision that has areas of special flood hazard, where streams exist but no base flood data have been provided (A zones), the Director shall review and reasonably utilize any available scientific or historic flood elevation, data, base flood elevation floodway data or future-conditions flood elevation data available from a federal, state, or other source in order to administer the provisions and standards of this Division. If data are not available from any of these sources, the following provisions shall apply:

1.

No encroachments, including structures or fill material, shall be located within an area equal to twice the width of the stream or fifty feet from the top of the bank of the stream, whichever is greater.

2.

In special flood hazard areas without base flood or future-conditions flood elevation data, new construction and substantial improvements shall have the lowest floor of the lowest enclosed area (including basement) elevated no less than three feet above the highest adjacent grade at the building site. Flood openings sufficient to facilitate automatic equalization of hydrostatic flood forces shall be provided for flood-prone enclosures in accordance with Sec. 9.5.4.A.5.a.

E.

Building Standards for Areas of Shallow Flooding (AO zones) Areas of special flood hazard may include designated AO shallow flooding areas. These areas have base flood depths of one foot to three feet above ground, with no clearly defined channel. In these areas the following provisions apply:

1.

All new construction and substantial improvements of residential and nonresidential structures shall have the lowest floor, including basement, elevated to no lower than one foot above the flood depth number specified on the flood insurance rate map (FIRM), above the highest adjacent grade. If no flood depth number is specified, the lowest floor, including basement, is elevated at least three feet above the highest adjacent grade. Flood openings sufficient to facilitate automatic equalization of hydrostatic flood forces shall be provided in accordance with the standards of Sec. 9.5.4.A.5.a;

2.

New construction and substantial improvement of a nonresidential structure may be floodproofed in lieu of elevation. The structure, together with attendant utility and sanitary facilities, must be designed to be watertight to the specified FIRM flood level plus one foot above the highest adjacent grade, with walls substantially impermeable to the passage of water, and structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. A licensed professional engineer or architect shall certify that the design and methods of construction are in accordance with accepted standards of practice, and shall provide such certification to the City using the FEMA floodproofing certificate along with the design and operation/maintenance plan; and

3.

Drainage paths shall be provided to guide floodwater around and away from any proposed structure.

F.

Standards for Subdivisions of Land  

1.

All subdivision proposals shall identify the areas of special flood hazard and areas of future-conditions flood hazard therein and provide base flood elevation data and future-conditions flood elevation data;

2.

All residential lots in a subdivision proposal shall have sufficient buildable area outside of the future-conditions floodplain such that encroachments into the future-conditions floodplain for residential structures will not be required;

3.

All subdivision plans will provide the elevations of proposed structures in accordance with Sec. 9.5.2.C.

G.

Standards for Utilities  

1.

All new and replacement water supply and sanitary sewerage systems are designed to minimize or eliminate:

a.

Infiltration of floodwaters into the systems; and

b.

Discharges from the systems into floodwaters.

2.

On-site waste disposal systems are located outside the floodplain to avoid impairment to them, or contamination from them during flooding.

( Ord. of 4-17-2018(7) , §§ 9-54—9-60)