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 in accordance with § 46-14B. 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, 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 by the permit
applicant for subdivision proposals and other proposed developments (including
proposals for manufactured home and recreational vehicle parks and subdivisions)
greater than either 50 lots or five acres.
E.
Encroachments.
(1)
All proposed development in riverine areas where no flood elevation data are available (unnumbered A Zones) shall be reviewed as set forth in § 46-12A(3) to determine the effects of the encroachment on the flood-carrying capacity of the stream. The local administrator may require submission of additional technical analyses and data necessary to complete the determination.
(2)
In all areas of special flood hazard in which base flood elevation data are available pursuant to § 46-12B or Subsection D(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.
(4)
Notwithstanding any other provisions of this chapter,
certain development in Zones A1 - 30, AE and AH may be permitted to increase
the water surface elevation of the base flood (e.g. dams, levees, etc.), provided
that the Mayor endorses application to the Federal Emergency Management Agency
(FEMA), the permit applicant provides all necessary data and analyses and
pays all fees and FEMA approval is received.
(5)
The local administrator shall require within Zones AH
and AO adequate drainage paths around structures on slopes to guide floodwaters
around and away from proposed structures.
In all areas of special flood hazard where base flood elevation data has been provided as set forth in § 46-6, Basis for establishing areas of special flood hazard, and § 46-12B, Use of other base flood and floodway data, the following standards are required:
A.
Residential construction. New construction and substantial
improvements of residential structures shall:
(1)
In Zones A1 - 30, AE and AH, have the lowest floor, including
basement or cellar, elevated to or above the base flood elevation.
(2)
In all areas of special flood hazard, have 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 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.
(3)
Within any AO Zone, have the lowest floor, including
basement, elevated above the highest adjacent grade at least as high as the
depth number specified in feet on the community's FIRM (at least two feet
if no depth number is specified).
(4)
Within any A Zone, when no base flood data are available,
have the lowest floor elevated at least three feet above the highest adjacent
grade.
B.
Manufactured homes and recreational vehicles.
(1)
A manufactured home that is placed or substantially improved
on a site in an A1 - 30, AE or AH Zone that is either outside of a manufactured
home park or subdivision; in a new manufactured home park or subdivision as
herein defined; in an expansion to an existing manufactured home park or subdivision
as herein defined; or in an existing manufactured home park or subdivision
as herein defined on which a manufactured home has incurred substantial damage
as the result of a flood shall be elevated on a permanent foundation such
that the lowest floor is elevated to or above the base flood elevation and
is securely anchored to an adequately anchored foundation system to resist
flotation, collapse and lateral movement.
(2)
A manufactured home to be placed or substantially improved on a site located in a A1 - 30, AE or AH Zone in a manufactured home park or subdivision, as herein defined, that is not subject to the provisions of Subsection B(1) shall be elevated so that either the lowest floor of the manufactured home is at or above the base flood elevation or the manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than 36 inches in height above grade and are securely anchored to an adequately anchored foundation system.
(3)
New construction or substantial improvements of manufactured
homes in Zone A, where no base flood elevation data are available, shall be
elevated at least three feet above the highest adjacent grade.
C.
Nonresidential construction.
(1)
In Zones A1 - 30, AE and AH, new construction and substantial
improvements of any commercial, industrial or other nonresidential structure,
together with attendant utility and sanitary facilities, shall either:
(a)
Have the lowest floor, including basement or cellar,
elevated to or above the base flood elevation; or
(b)
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.
(2)
In an AO Zone, all new construction and substantial improvements
shall have the lowest floor, including basement, elevated above the highest
adjacent grade at least as high as the depth number specified in feet on the
community's FIRM (at least two feet if no depth number is specified).
(3)
In an A Zone, when no base flood data are available,
have the lowest floor elevated at least three feet above the highest adjacent
grade.
(4)
If the structure is to be elevated, 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 (without human intervention) equalize
hydrostatic 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 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.
(5)
If the structure is to be floodproofed, 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 for meeting the provisions of Subsection C(1)(b), including the specific elevation (in relation to mean sea level) to which the structure is floodproofed.
(6)
The local administrator shall maintain on record a copy
of all such certificates noted in this section.
Located within areas of special flood hazard are areas designated as floodways (see definition, § 46-4). 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 § 46-6 or, when applicable, § 46-12B, 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.
