§ 58-70. General standards.

(a)

Provisions for all areas of special flood hazard. In all areas of special flood hazard the following provisions apply:

(1)

New construction of principal buildings (residential or nonresidential), including manufactured homes, shall not be allowed within the limits of the future-conditions floodplain unless all requirements of sections 58-66 and 58-67 have been met;

(2)

New construction or substantial improvements of existing structures, including manufactured homes shall be anchored to prevent flotation, collapse or lateral movement of the structure;

(3)

New construction or substantial improvements of existing structures shall be constructed with materials and utility equipment resistant to flood damage;

(4)

New construction or substantial improvements of existing structures, including manufactured homes, shall be constructed by methods and practices that minimize flood damage;

(5)

Elevated buildings. All substantial improvements of existing structures that include any fully enclosed area located below the lowest floor formed by foundation and other exterior walls shall be designed so as to be an unfinished or flood resistant enclosure. The enclosure shall be 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 professional engineer or architect or meet the following minimum criteria:

1.

Provide a minimum of two openings having a total net area of not less than 100 square inches for every square foot of enclosed area subject to flooding;

2.

The bottom of all openings shall be no higher than one foot above grade; and,

3.

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 article, 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 partitioned or finished into separate rooms.

(6)

All heating and air conditioning equipment and components, all electrical, ventilation, plumbing, and other service facilities shall be 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)

Substantial improvements to manufactured homes shall be anchored to prevent 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 standard shall be in addition to and consistent with applicable state requirements for resisting wind forces;

(8)

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

(9)

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

(10)

On-site waste disposal systems shall be located and constructed to avoid impairment to them or contamination from them during flooding; and,

(11)

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

(12)

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.

(b)

Building standards for structures and buildings within the future-conditions floodplain.

(1)

Residential buildings.

a.

New construction of principal buildings, including manufactured homes shall not be allowed within the limits of the future-conditions floodplain unless all requirements of sections 58-66, 58-67, and 58-69 have been met. If all of the requirements of sections 58-66, 58-67 and 58-69 have been met, all new construction 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 equalize the hydrologic flood forces on exterior walls and to facilitate the unimpeded movements of floodwaters shall be provided in accordance with standards of subsection 50-70(a)(5).

b.

Substantial improvement of any principal structure or manufactured home shall not be allowed within the limits of the future-conditions floodplain unless all requirements of sections 58-66, 58-67, and 58-69 have been met. If all the requirements of sections 58-66, 58-67, and 58-69 have been met, all 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 a structure, openings sufficient to equalize the hydrologic flood forces on exterior walls and to facilitate the unimpeded movements of floodwaters shall be provided in accordance with standards of subsection 58-70(a)(5).

(2)

Nonresidential buildings.

a.

New construction. New construction of principal non-residential structures shall not be allowed within the limits of the future-conditions floodplain unless all requirements of sections 58-66, 58-67 and 58-69 have been met. If all of the requirements of sections 58-66, 58-67 and 58-69 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 standards of subsection 50-70(a)(5). New construction that has met all of the requirements of sections 58-66, 58-67, and 58-69 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 improvement of any principal non-residential structures shall not be allowed within the limits of the future conditions floodplain unless all requirements of sections 58-66, 58-67, and 58-69 have been met. If all of the requirements of sections 58-66, 58-67 and 58-69 have been met, all 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 standards of subsection 50-70(a)(5). Substantial improvement that has met all of the requirements of sections 58-66, 58-67, and 58-69 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.

(3)

Accessory structures and facilities. Accessory structures and facilities (i.e., barns, sheds, gazebos, detached garages, parking lots, recreational facilities and other similar nonhabitable structures and facilities) which are permitted to be located within the limits of the floodplain shall be constructed of flood-resistant materials and designed to pass all floodwater in accordance with subsection 58-70(a)(5) and be anchored to prevent flotation, collapse or lateral movement of the structure.

(4)

Standards for recreational vehicles. All recreational vehicles placed on sites must either:

a.

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

b.

The recreational vehicle must meet all the requirements for "Residential Buildings—Substantial Improvements," (subsection 58-70(b)(1)b.) including the anchoring and elevation requirements.

(5)

Standards for manufactured homes.

a.

New manufactured homes shall not be allowed to be placed within the limits of the future-conditions floodplain unless all requirements of sections 58-66 and 58-67 have been met.

b.

New manufactured homes placed and/or substantially improved manufactured homes in an existing manufactured home park or subdivision shall be elevated so that either:

1.

The lowest floor of the manufactured home is elevated no lower than three feet above the level of the base flood elevation; or

2.

One foot above the future-conditions flood elevation, whichever is higher; or

c.

All manufactured homes must be securely anchored to an adequately anchored foundation system to resist floatation, collapse and lateral movement in accordance with standards of section 58-70.

(c)

Building standards for structures and buildings authorized adjacent to the future-conditions floodplain.

(1)

Residential buildings. For new construction or substantial improvement of any principal residential building or manufactured home, the elevation of the lowest floor, including basement and access to the building, shall be at least three feet above the level of the highest base flood (100-year) elevation or one foot above the level of the future-conditions flood elevation, whichever is highest.

(2)

Nonresidential buildings. For new construction or substantial improvement of any principal non-residential building, the elevation of the lowest floor, including basement and access to the building, shall be at least one foot above the level of the highest base flood (100-year) elevation adjacent to the building or at least as high as the future-conditions flood elevation whichever is highest.

(d)

Building standards for residential single-lot developments 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 and floodway data, or future-conditions flood elevation data available from a federal, state, local or other source, in order to administer the provisions and standards or this article. 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 50 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 of existing structures 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. Openings sufficient to facilitate the unimpeded movements of floodwaters shall be provided in accordance with subsection 58-70(a)(5).

(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 to three feet above ground, with no clearly defined channel. In these areas the following provisions apply:

(1)

New 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, shall be elevated at least three feet above the highest adjacent grade. Openings sufficient to facilitate the unimpeded movements of floodwaters shall be provided in accordance with standards for "elevated buildings." The applicant's or owner's engineer shall certify to the director that the lowest floor elevation level and the record shall become a permanent part of the permit file;

(2)

New 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 flood insurance rate map (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 registered professional engineer or architect shall certify that the design and methods of construction are in accordance with accepted standards of practice; and

(3)

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

(f)

Standards for subdivisions.

(1)

All subdivision proposals shall identify the special flood hazard area and provide base flood 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 elevation of proposed structure(s) and pad(s). If the site is filled above the base flood plus three feet or future-conditions flood elevation plus one foot, whichever is highest, the lowest floor and pad elevations shall be certified by a professional engineer or surveyor registered in the state and provided to the director;

(4)

All subdivision proposals shall be consistent with the need to minimize flood damage;

(5)

All subdivision proposals shall have public utilities and facilities such as water, sanitary sewer, gas, and electrical systems located and constructed to minimize or eliminate infiltration of floodwaters, and discharges from the systems into floodwaters; and

(6)

All subdivision proposals shall have adequate drainage and stormwater management facilities per the requirements of Cobb County to reduce potential exposure to flood hazards.

(g)

Standards for utilities.

(1)

All new and replacement water supply and sanitary sewerage systems shall be 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 shall be located outside the floodplain to avoid impairment to them, or contamination from them during flooding.

(Ord. of 4-13-04; Ord. of 2-27-07; Amd. of 10-23-18)