§ 700-40. Development Provisions.

700-40.1   Structures and Buildings Authorized in the Floodplain.

A.

Residential Buildings.

1.

Substantial improvements. For substantial improvements to all or part of an existing principal residential buildings, the requirements of Sections 700-20.1 through 700-20.3 and Sections 700-30.1 et seq., shall apply and the elevation of the lowest floor, including basement and access to the building, shall be elevated at least three feet above the level of the highest base flood elevation (100-year) adjacent to the building or at least 1 foot above the future conditions flood elevation whichever is highest. Openings sufficient to facilitate the unimpeded movements of flood waters shall be provided in accordance with Section 700-40.6 titled "Elevated buildings".

B.

Non-Residential Buildings.

1.

Substantial improvements. Substantial improvements to all or part of an existing principal non-residential buildings may be authorized by the Department to be flood proofed in lieu of being elevated, in accordance with Section 700-40.6 titled "Elevated buildings", provided that all areas of the building less than 1 foot above the base flood elevation or below the future conditions flood elevation, whichever is highest, 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. A registered professional engineer or architect shall certify to the Department that the standards of this subsection are satisfied and shall provide the Department a flood proofing certificate including flood proofing level immediately after flood proofing is completed. The certification shall be prepared by or under the direct supervision of a professional engineer or architect and certified by same. The requirements of Sections 700-20.1 through 700-20.3 and Sections 700-30.1, et seq., shall also apply.

C.

Accessory and non-habitable buildings and structures. Accessory and non-habitable structures (i.e., barns, sheds, gazebos, and other similar structures) which are permitted to be located within the limits of the floodplain under the provisions of Title 2 of this UDO shall be designed and constructed of flood resistant materials to pass all floodwater and be anchored to prevent flotation, collapse, or lateral movement of the structure in a manner consistent with Chapter 700.

D.

Drainage structures and impoundments. Drainage structures and impoundments may be authorized provided they are designed and constructed pursuant to the requirements of this UDO, are approved by the Department, and are consistent with the requirements of Chapter 700. Detention facilities may be located within the future conditions floodplain if the future conditions flood storage capacity is not reduced by the dam and water impounded behind the dam as required in Section 700-30.3.A.

700-40.2   Structures and Buildings Authorized Adjacent to the Future Conditions Floodplain.

A.

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 adjacent to the building or at least 1 foot above the future conditions flood elevation whichever is highest.

B.

Non-residential 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 1 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.

700-40.3   Building Permit Requirements. Prior to the issuance of a building permit for a site which contains or is adjacent to the floodplain, a drawing which shows the elevation of the proposed lowest floor of the building, including basement, the limits of the floodplain, and the highest future conditions flood elevation and base flood elevation (100-year) adjacent to the building, must be submitted to the Department for approval. If the proposed development is located in multiple flood zones or multiple base flood elevation cross the proposed building site, the higher or more restrictive base flood elevation or future condition elevation and development standards shall take precedence at the building site. Proposed grading encroachments must be shown on this drawing. Elevations shall be referenced to an accurate topographical reference (e.g., a recorded final plat whereon the future conditions and the base floodplain is shown).

700-40.4   Construction Stage. For all new construction and substantial improvements on sites with a floodplain management/ flood damage prevention plan which may be shown on a Residential Drainage Plan, the permit holder shall provide to Gwinnett County a certified as-built Elevation Certificate including the lowest floor elevation. A final Elevation Certificate shall be provided after completion of construction including final grading of the site. Any lowest floor certification made relative to mean sea level shall be prepared by or under the direct supervision of a licensed land surveyor or professional engineer and certified by the same.

Any work undertaken prior to submission and approval of the certification shall be at the permit holder's risk. No framing inspection shall be completed or approved by the Department until such required certification is received and verified by the Department. Deficiencies detected by such review shall be corrected by the permit holder immediately and prior to further progressive work being allowed to proceed. Failure to submit the survey or failure to make said corrections required thereby shall be cause to issue a stop work order for the project.

700-40.5   Provisions for Flood Hazard Reduction. All new construction and substantial improvement of structures adjacent (residential or non-residential) to special flood hazard areas shall comply with the applicable requirements of the Gwinnett County Construction Code and the following:

A.

Buildings/structures shall be constructed with materials and utility equipment resistant to flood damage;

B.

Buildings/structures shall be constructed by methods and practices that minimize flood damage;

C.

Electrical, heating, ventilation, plumbing, air conditioning equipment and other service facilities shall be constructed or located three (3) feet above the base flood elevation or one (1) 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;

D.

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

E.

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;

F.

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

G.

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

H.

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;

I.

New development shall include adequate drainage and stormwater management facilities per requirement of Gwinnett County to reduce exposure to flood hazards;

J.

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;

K.

When only a portion of a parcel is located within a flood zone or the future-conditions floodplain, all new and substantially improved structures on the parcel shall meet requirements of Chapter 700;

L.

Any alteration, repair, reconstruction or improvement to a structure which is not compliant with the provisions of Chapter 700, shall be undertaken only if the non-conformity is not furthered, extended or replaced.

M.

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

1.

All such proposals shall be consistent with the need to minimize flood damage within the flood prone area;

2.

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

3.

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

700-40.6   Elevated Buildings. All new construction or 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 flood water.

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 1 square inch for every square foot of enclosed area subject to flooding.

2.

The bottom of all openings shall be no higher than 1 foot above grade.

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 Section 700-40.1.A or Section 700-40.1.B, 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.

C.

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

700-40.7   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 use 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 of Chapter 700.

If data are not available from any of these sources, the following provisions shall apply:

A.

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.

B.

In special flood hazard areas without base flood elevation 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 Section 700-40.6.

700-40.8   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).

B.

The recreational vehicle must meet all the requirements for residential buildings including the anchoring and elevation requirements.