In all areas of special flood hazard 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.
C.
Utilities.
(1)
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. 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 areas of special flood hazard set forth in § 95-12A(3), Permit review. 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 § 95-12B or 95-13D(4) 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.
In all areas of special flood hazard where base flood elevation data has been provided as set forth in § 95-6, Basis for establishing areas of special flood hazard, and § 95-12B, Use of other base flood and floodway data, the following standards are required:
A.
Residential construction. New construction and substantial
improvements of any residential 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 shall be provided.
(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 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 shall be provided.
(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 and with structural
components having the capability of resisting hydrostatic and hydrodynamic
loads and the 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 Zoning Enforcement Officer shall maintain on record
a copy of all such certificates noted in this section.
C.
Construction standards for areas of special flood hazard 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 § 95-12B 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 to 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 shall be provided.
(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.
Located within areas of special flood hazard are areas designated as floodways (see definition, § 95-4). 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 §§ 95-6 and 95-12B, 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.
