In all areas of special flood hazards, the following standards
are required:
A. Anchoring.
(1) All
new construction and substantial improvements shall be anchored to
prevent flotation, collapse or lateral movement of the structure.
(2) All
manufactured homes shall be installed using methods and practices
which minimize flood damage. Manufactured homes must be elevated and
anchored to resist flotation, collapse or lateral movement. Manufactured
homes shall be elevated to or above the base flood elevation or two
feet above the highest adjacent grade when no base flood elevation
has been determined. Methods of anchoring may include, but are not
to be 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. Construction
materials and methods.
(1) All
new construction and substantial improvements shall be constructed
with materials and utility equipment resistant to flood damage.
(2) All
new construction and substantial improvements shall be constructed
using methods and practices that minimize flood damage.
C. Utilities.
(1) Electrical,
heating, ventilation, plumbing, 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. When designed for location below the base flood elevation,
a professional engineer's or architect's certification is required.
(2) All
new and replacement water supply systems shall be designed to minimize
or eliminate infiltration of floodwaters into the system.
(3) New
and replacement sanitary sewage systems shall be designed to minimize
or eliminate infiltration of floodwaters.
(4) On-site
waste disposal systems shall be located to avoid impairment to them
or contamination from them during flooding.
D. Subdivision
proposals.
(1) All
subdivision proposals shall be consistent with the need to minimize
flood damage.
(2) All
subdivision proposals shall have public utilities and facilities,
such as sewer, gas, electrical and water systems, located and constructed
to minimize flood damage.
(3) All
subdivision proposals shall have adequate drainage provided to reduce
exposure to flood damage.
(4) Base
flood elevation data shall be provided for subdivision proposals and
other proposed developments (including proposals for manufactured
home parks and subdivisions) greater than either 50 lots or five acres.
E. Encroachments.
(1) All proposed development in riverine situations where no flood elevation data is available (unnumbered A Zones) shall be analyzed to determine the effects on the flood-carrying capacity of the area of special flood hazards set forth in §
125-12A, Permit review, Subdivision (3). This may require the submission of additional technical data to assist in the determination.
(2) In all areas of special flood hazard in which base flood elevation data is available pursuant to §
125-12B or Subsection
D(4) of this section and no floodway has been determined, the cumulative effects of any proposed development, when combined with all other existing and anticipated development, shall not increase the water surface elevation of the base flood more than one foot at any point.
(3) In all areas of the special flood hazard where floodway data is provided or available pursuant to §
125-12B, the requirements of §
125-15, Floodways, shall apply.
In all areas of special flood hazards where base flood elevation data has been provided as set forth in §
125-6, Basis for establishing areas of special flood hazard, and §
125-12B, Use of other base flood data, the following standards are required:
A. Residential
construction. New construction and substantial improvements of any
resident structure shall:
(1) Have
the lowest floor, including basement or cellar, elevated to or above
the base flood elevation.
(2) Have
fully enclosed areas below the lowest floor that are subject to flooding
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 licensed professional
engineer or architect or meet or exceed the following minimum criteria:
(a) 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.
(b) The bottom of all such openings shall be no higher than one foot
above the lowest adjacent finished grade.
(c) Openings may be equipped with louvers, valves, screens or other coverings
or devices, provided that they permit the automatic entry and exit
of floodwaters.
B. Nonresidential
construction. New construction and substantial improvements of any
commercial, industrial or other nonresidential structure, together
with attendant utility and sanitary facilities, shall either have
the lowest floor, including basement or cellar, elevated to or above
the base flood elevation; or be floodproofed so that the structure
is watertight below the base flood level with walls substantially
impermeable to the passage of water. All structural components located
below the base flood level must be capable of resisting hydrostatic
and hydrodynamic loads and the effects of buoyancy.
(1) If
the structure is to be elevated, fully enclosed areas below the base
flood elevation shall be designed to automatically (without human
intervention) allow for the entry and exit of floodwaters for the
purpose of equalizing hydrostatic flood forces on exterior walls.
Designs for meeting this requirement must either be certified by a
licensed professional engineer or a licensed architect or met the
following criteria:
(a) 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.
(b) The bottom of all such openings shall be no higher than one foot
above the lowest adjacent finished grade.
(c) Openings may be equipped with louvers, valves, screens or other coverings
or devices, provided that they permit the automatic entry and exit
of floodwaters.
(2) If
the structure is to be floodproofed:
(a) A licensed professional engineer or architect shall develop and/or
review structural design, specifications and plans for the construction
and shall certify that the design and methods of construction are
in accordance with accepted standards of practice to make the structure
watertight with walls substantially impermeable to the passage of
water, with structural components having the capability of resisting
hydrostatic and hydrodynamic loads and effects of buoyancy.
(b) A licensed professional engineer or licensed land surveyor shall
certify the specific elevation (in relation to mean sea level) to
which the structure is floodproofed.
(3) The
local administrator shall maintain on record a copy of all such certificates
noted in this section.
C. Construction standards for areas of special flood hazards without base flood elevations. New construction or substantial improvements of structures, including manufactured homes, shall have the lowest floor including basement elevated to or above the base flood elevation as may be determined in §
125-12B or two feet above the highest adjacent grade where no elevation data is available.
(1) New
construction or substantial improvements of structures, including
manufactured homes, shall have the lowest floor including basement
elevated at least two feet above the highest adjacent grade next to
the proposed foundation of the structure.
(2) Fully
enclosed areas below the lowest floor that are subject to flooding
shall be designed to automatically (without human intervention) allow
for the entry and exit of floodwaters for the purpose of equalizing
hydrostatic flood forces on exterior walls. Designs for meeting this
requirement must either be certified by a licensed professional engineer
or a licensed architect or meet the following criteria:
(a) 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.
(b) The bottom of all such openings shall be no higher than one foot
above the lowest adjacent finished grade.
(c) Openings may be equipped with louvers, valves, screens or other coverings
or openings, provided that they permit the automatic entry and exit
of floodwaters.
Located within areas of special flood hazard are areas designated as floodways (see definitions in Article
II). The floodway is an extremely hazardous area due to high-velocity floodwaters carrying debris and posing additional threats from potential erosion forces. When floodway data is available for a particular site, as provided by §§
125-6 and
125-12B, all encroachments, including fill, new construction, substantial improvements and other development, are prohibited within the limits of the floodway unless a technical evaluation demonstrates that such encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge.