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 anchored to resist flotation, collapse
or lateral movement. 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)
All new and replacement water supply systems shall be designed to
minimize or eliminate infiltration of floodwaters into the system;
(2)
New and replacement sanitary sewage systems shall be designed to
minimize or eliminate infiltration of floodwaters into the systems
and discharge from the systems into floodwaters;
(3)
On-site waste disposal systems shall be located to avoid impairment
to them or contamination from them during flooding; and
(4)
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.
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; and
(4)
Base flood elevation data shall be provided for subdivision proposals
and other proposed development which contain at least 50 lots or five
acres (whichever is less).
E.
Enclosure openings. All new construction and substantial improvements
having fully enclosed areas below the lowest floor that are usable
solely for parking of vehicles, building access or storage in an area
other than a basement and which are subject to flooding shall be 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 registered professional
engineer or architect or must meet or exceed the following minimum
criteria: 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. The bottom of all openings shall be
no higher than one foot above grade. Openings may be equipped with
screens, louvers, or other covering or devices, provided that they
permit the automatic entry and exit of floodwaters.
In all areas of special flood hazard where base flood elevation data have been provided as set forth in § 74-3, Basis for establishing areas of special flood hazard or in § 74-10B, Use of other base flood data, the following standards are required:
A.
Residential construction.
(1)
New construction and substantial improvement of any residential structure
shall have the lowest floor, including basement, together with the
attendant utilities and sanitary facilities, elevated to or above
base flood elevation.
(2)
Within any AO Zone on the municipality's FIRM, all new construction
and substantial improvement of any residential structure shall have
the lowest floor, including basement, elevated above the highest adjacent
grade at least as high as the depth number specified in feet (at least
two feet if no depth number is specified), and adequate drainage paths
around structures on slopes to guide floodwaters around and away from
proposed structures are required.
B.
Nonresidential construction. In an area of special flood hazard,
all new construction and substantial improvement of any commercial,
industrial or other nonresidential structure shall have the lowest
floor, including basement, together with the attendant utilities and
sanitary facilities:
(1)
Either:
(a)
Elevated to the level of the base flood elevation; and
(b)
Within any AO Zone on the municipality's DFIRM, all new
construction and substantial improvement of any commercial, industrial
or other nonresidential structure shall have the lowest floor, including
basement, elevated above the highest adjacent grade at least as high
as the depth number specified in feet (at least two feet if no depth
number is specified), and adequate drainage paths around structures
on slopes to guide floodwaters around and away from proposed structures
are required.
(2)
Or:
(a)
Floodproofed so that below the base flood level the structure
is watertight with walls substantially impermeable to the passage
of water;
(b)
Having structural components capable of resisting hydrostatic
and hydrodynamic loads and effects of buoyancy; and
(c)
Certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting the applicable provisions of this subsection. Such certification shall be provided to the official as set forth in § 74-10C(2)(b).
Located within areas of special flood hazard established in § 74-3 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential, the following provisions apply:
A.
Prohibit encroachments, including fill, new construction, substantial
improvements, and other development unless a technical evaluation
demonstrates that encroachment shall not result in any increase in
flood levels during the occurrence of the base flood discharge.
C.
In all areas of special flood hazard in which base flood elevation
data has been provided and no floodway has been designated, the cumulative
effect 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 0.2 foot at any point.
