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 § 186-13A(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 § 186-13B or 186-14D(4) and no floodway has been determined, the cumulative effects of an 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 § 186-7, Basis for establishing areas of special flood hazard, and § 186-13B, 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 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 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 § 186-13B 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)
The 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 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 definition of "floodway" in Article II, § 186-5.) 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 §§ 186-7 and 186-13B, 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.
