All uses, activities, and development occurring within any floodplain
district, including placement of manufactured homes, shall be undertaken
only upon the issuance of a zoning permit. Such development shall
be undertaken only in strict compliance with the provisions of this
chapter and with all other applicable codes and ordinances, such as
the Virginia Uniform Statewide Building Code and the Northumberland
County Subdivision Ordinance.[1] Prior to the issuance of any such permit, the Floodplain
Administrator shall require all applications to include compliance
with all applicable state and federal laws and shall review all sites
to assure they are reasonably safe from flooding. Under no circumstances
shall any use, activity, and/or development adversely affect the capacity
of the channels or floodway of any watercourse, drainage ditch, or
any other drainage facility or system.
A.
Site plans and permit applications. All applications for development
within any floodplain district and all building permits issued for
the floodplain shall incorporate the following information:
(1)
The elevation of the base flood at the site.
(2)
The elevation of the lowest floor (including basement) or, in V or
VE Zones, the lowest horizontal structural member.
(3)
For structures to be floodproofed (nonresidential only), the elevation
to which the structure will be floodproofed.
(4)
Topographic information showing existing and proposed ground elevations.
B.
General standards. The following provisions shall apply to all permits:
(2)
Manufactured homes shall be anchored to prevent flotation, collapse,
or lateral movement. Methods of anchoring may include, but are not
limited to, use of over-the-top or frame ties to ground anchors. This
standard shall be in addition to and consistent with applicable state
anchoring requirements for resisting wind forces.
(3)
New construction and substantial improvements shall be constructed
with materials and utility equipment resistant to flood damage.
(4)
New construction or substantial improvements shall be constructed
by methods and practices that minimize flood damage.
(5)
Electrical, heating, ventilation, plumbing, air-conditioning equipment
and other service facilities, including duct work, shall be designed
and/or located so as to prevent water from entering or accumulating
within the components during conditions of flooding.
(6)
New and replacement water supply systems shall be designed to minimize
or eliminate infiltration of floodwaters into the system.
(7)
New and replacement sanitary sewage systems shall be designed to
minimize or eliminate infiltration of floodwaters into the systems
and discharges from the systems into floodwaters.
(8)
On-site waste disposal systems shall be located and constructed to
avoid impairment to them or contamination from them during flooding.
(9)
Storm drainage facilities shall be designed to convey the flow of
stormwater runoff in a safe and efficient manner. The system shall
insure proper drainage along streets, and provide positive drainage
away from buildings. The system shall also be designed to prevent
the discharge of excess runoff onto adjacent properties.
(10)
Prior to any proposed alteration or relocation of any channels
or of any watercourse, stream, etc., within this jurisdiction, a permit
shall be obtained from the United States Corps of Engineers, the Virginia
Department of Environmental Quality, and the Virginia Marine Resources
Commission. (A joint permit application is available from any of these
organizations.) Furthermore, in riverine areas, notification of the
proposal shall be given by the applicant to all affected adjacent
jurisdictions, the Department of Conservation and Recreation (Division
of Dam Safety and Floodplain Management) and the Federal Emergency
Management Agency.
(11)
The flood-carrying capacity within an altered or relocated portion
of any watercourse shall be maintained.
C.
Specific standards. In all special flood hazard areas where base flood elevations have been provided in the Flood Insurance Study or generated according to Article IV, § 76-15, the following provisions shall apply:
(1)
Residential construction. New construction or substantial improvement of any residential structure (including manufactured homes) shall have the lowest floor, including basement, elevated at least two feet above the base flood level. Residential construction in VE Zones and Coastal A Zones shall comply with Article IV, § 76-15D and E. Residential construction in AO Zones shall comply with § 76-15F.
(2)
Nonresidential construction. New construction or substantial improvement of any commercial, industrial, or nonresidential building (or manufactured home) shall have the lowest floor, including basement, elevated at least two feet above the base flood level. Nonresidential construction in VE Zones and Coastal A Zones shall comply with Article IV, § 76-15D and E. Nonresidential construction in AO Zones shall comply with § 76-15F. Nonresidential buildings located in all A1-30, AE, and AH Zones may be floodproofed in lieu of being elevated, provided that all areas of the building components below the elevation corresponding to the BFE plus one foot are watertight, with walls substantially impermeable to the passage of water, and use structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. A registered professional engineer or architect shall certify that the standards of this subsection are satisfied. Such certification, including the specific elevation (in relation to mean sea level) to which such structures are floodproofed, shall be maintained by the Floodplain Administrator.
(3)
Elevated buildings. In Zone A or AE, fully enclosed areas, of new
construction or substantially improved structures, which are below
the regulatory flood-protection elevation shall:
(a)
Not be designed or used for human habitation, but shall only
be used for parking of vehicles, building access, or limited storage
of maintenance equipment used in connection with the premises. Access
to the enclosed area shall be the minimum necessary to allow for parking
of vehicles (garage door) or limited storage of maintenance equipment
(standard exterior door), or entry to the living area (stairway or
elevator).
(b)
Be constructed entirely of flood-resistant materials below the
regulatory flood protection elevation;
(c)
Include measures to automatically equalize hydrostatic flood
forces on walls by allowing for the entry and exit of floodwaters.
To meet this requirement, the openings must either be certified by
a professional engineer or architect or meet the following minimum
design criteria:
[1]
Provide a minimum of two openings on different sides of each
enclosed area subject to flooding.
[2]
The total net area of all openings must be at least one square
inch for each square foot of enclosed area subject to flooding.
[3]
If a building has more than one enclosed area, each area must
have openings to allow floodwaters to automatically enter and exit.
[4]
The bottom of all required openings shall be no higher than
one foot above the adjacent grade.
[5]
Openings may be equipped with screens, louvers, or other opening
coverings or devices, provided they permit the automatic flow of floodwaters
in both directions.
[6]
Foundation enclosures made of flexible skirting are not considered
enclosures for regulatory purposes, and, therefore, do not require
openings. Masonry or wood underpinning, regardless of structural status,
is considered an enclosure and requires openings as outlined above.
(4)
Manufactured homes. All manufactured homes placed, or substantially improved, on individual lots or parcels must meet all the requirements for new construction, including the elevation and anchoring requirements in Article IV, § 76-14B(1) and (2), and § 76-14C(1). Manufactured homes placed in VE Zones and Coastal A Zones must meet the requirements of Article IV, § 76-15D(7), and § 76-15E.
(5)
Recreational vehicles. All recreational vehicles placed in AE Zones
must either:
(a)
Be on site for fewer than 180 consecutive days;
(b)
Be fully licensed and ready for highway use (A recreational
vehicle is ready for highway use if it is on its wheels or jacking
system, is attached to the site only by quick-disconnect-type utilities
and security devices and has no permanently attached additions.);
or
(6)
Accessory
structures (excluding water-dependent facilities).
[Added 11-10-2021]
(a)
Accessory structures of any size shall be prohibited within the SFHA
and no variance shall be granted for accessory structures; or
(b)
Accessory structures in the SFHA shall comply with the elevation requirements and other requirements of Article IV, § 76-14C(2); if not elevated or dry floodproofed, shall:
[1]
Not be used for human habitation;
[2]
Be limited to no more than 600 square feet in total floor area;
[3]
Be usable only for parking of vehicles or limited storage;
[4]
Be constructed with flood-damage-resistant materials below the base
flood elevation;
[5]
Be constructed and placed to offer the minimum resistance to the
flow of floodwaters;
[6]
Be anchored to prevent flotation;
[7]
Have electrical service and mechanical equipment elevated to or above
the base flood elevation;
[8]
Be provided with flood openings which shall meet the following criteria:
[a]
There shall be a minimum of two flood openings on different sides
of each enclosed area; if a building has more than one enclosure below
the lowest floor, each such enclosure shall have flood openings on
exterior walls.
[b]
The total net area of all flood openings shall be at least one square
inch for each square foot of enclosed area (nonengineered flood openings),
or the flood openings shall be engineered flood openings that are
designed and certified by a licensed professional engineer to automatically
allow entry and exit of floodwaters; the certification requirement
may be satisfied by an individual certification or an evaluation report
issued by the ICC Evaluation Service, Inc.
[c]
The bottom of each flood opening shall be one foot or less above
the higher of the interior floor or grade, or the exterior grade,
immediately below the opening.
[d]
Any louvers, screens or other covers for the flood openings shall
allow the automatic flow of floodwaters into and out of the enclosed
area.
A.
Standards for the Floodway District. The following provisions shall
apply within the Floodway District:
(1)
Encroachments, including fill, new construction, substantial improvements
and other developments are prohibited unless certification such as
hydrologic and hydraulic analyses (with supporting technical data)
is provided demonstrating that encroachments shall not result in any
increase in flood levels during occurrence of the base flood. Hydrologic
and hydraulic analyses shall be undertaken only by professional engineers
or others of demonstrated qualifications, who shall certify that the
technical methods used correctly reflect currently accepted technical
concepts. Studies, analyses, computations, etc., shall be submitted
in sufficient detail to allow a thorough review by the Floodplain
Administrator. Development activities which increase the water surface
elevation of the base flood may be allowed, provided that the developer
or applicant first applies, with Northumberland County's endorsement,
for a conditional Flood Insurance Rate Map and floodway revision and
receives the approval of the Federal Emergency Management Agency.
(3)
The placement of manufactured homes (mobile homes) is prohibited,
except in an existing manufactured home (mobile home) park or subdivision.
A replacement manufactured home may be placed on a lot in an existing
manufactured home park or subdivision, provided the anchoring, elevation,
and encroachment standards are met.
B.
Standards for the Special Floodplain District. The following provisions
shall apply within the Special Floodplain District:
(1)
Until a regulatory floodway is designated, no new construction, substantial
improvements, or other development (including fill) shall be permitted
within the areas of special flood hazard, designated as Zones A1-30
and AE on the Flood Insurance Rate Map, unless it is demonstrated
that the cumulative effect of the proposed development, when combined
with all other existing and anticipated development, will not increase
the water surface elevation of the base flood more than one foot at
any point within Northumberland County. The requirement in 44 CFR
60.3(c)(10) only applies along rivers, streams, and other watercourses
where FEMA has provided base flood elevations. The requirement does
not apply along lakes, bays and estuaries, and the ocean coast.
(2)
Development activities in Zones A1-30, AE, and AH on Northumberland
County's Flood Insurance Rate Map which increase the water surface
elevation of the base flood by more than one foot may be allowed,
provided that the applicant first applies, with Northumberland County's
endorsement, for a conditional Flood Insurance Rate Map revision and
receives the approval of the Federal Emergency Management Agency.
C.
Standards for approximated floodplain. The following provisions shall
apply with the Approximated Floodplain District:
(1)
The Approximated Floodplain District shall be that floodplain area
for which no detailed flood profiles or elevations are provided but
where a one-hundred-year floodplain boundary has been approximated.
Such areas are shown as Zone A on the maps accompanying the Flood
Insurance Study. For these areas, the one-hundred-year flood elevations
and floodway information from federal, state, and other acceptable
sources shall be used, when available. Where the specific one-hundred-year
flood elevation cannot be determined for this area using other sources
of data, such as the United States Army Corps of Engineers Flood Plain
Information Reports, United States Geological Survey Flood-Prone Quadrangles,
etc., then the applicant for the proposed use, development and/or
activity shall determine this elevation. For development proposed
in the approximated floodplain, the applicant must use technical methods
that correctly reflect currently accepted technical concepts, such
as point on boundary, high-water marks, or hydrologic and hydraulic
analyses. Studies, analyses, computations, etc., shall be submitted
in sufficient detail to allow a thorough review by the Zoning Administrator.
(2)
The Floodplain Administrator reserves the right to require hydrologic
and hydraulic analyses for any development.
(a)
When such base flood elevation data is utilized, the lowest
floor shall be elevated at least one foot above the base flood level.
During the permitting process, the Floodplain Administrator shall
obtain:
[1]
The elevation of the lowest floor (including the basement) of
all new and substantially improved structures; and
[2]
If the structure has been floodproofed in accordance with the
requirements of this article, the elevation (in relation to mean sea
level) to which the structure has been floodproofed.
(3)
Base flood elevation data shall be obtained from other sources or
developed using detailed methodologies comparable to those contained
in an FIS for subdivision proposals and other proposed development
proposals (including manufactured home parks and subdivisions) that
exceed 50 lots or five acres, whichever is the lesser.
D.
Coastal High-Hazard District. These areas have special flood hazards
associated with wave action; therefore, the following additional provisions
shall apply:
(1)
All new construction shall be located 100 feet landward of the reach
of mean high tide;
(2)
There shall be no fill used as structural support. When nonstructural
fill is proposed in a coastal high-hazard area, appropriate engineering
analyses shall be conducted to evaluate the impacts of the fill prior
to issuance of a development permit.
(3)
There shall be no alteration of sand dunes which would increase potential
flood damage;
(4)
Within V and VE Zones on the Flood Insurance Rate Map, the Floodplain
Administrator shall obtain the elevation (in relation to mean sea
level) of the bottom of the lowest horizontal structural member of
the lowest floor (excluding pilings and columns) of all new and substantially
improved structures. The Floodplain Management Administrator shall
maintain a record of all such information.
(5)
All new construction and substantial improvements shall be elevated
on pilings and columns and must have the bottom of the lowest horizontal
structural member of the lowest floor (excluding the pilings or columns)
elevated at least two feet above the base flood level and the pile
or column foundation and structure attached thereto must be anchored
to resist floatation, collapse and lateral movement due to the effects
of wind and water loads acting simultaneously on all building components.
Wind and water loading values shall each have a one-percent chance
of being equaled or exceeded in any given year (one-percent-annual
chance). A registered professional engineer or architect shall develop
or review the structural design and methods of construction and shall
certify that design and methods of construction to be used are in
accordance with accepted standards of practice;
(6)
Provide that all new construction and substantial improvements within
Zone VE on the community's FIRM have the space below the lowest floor
either free of obstruction or constructed with nonsupporting breakaway
walls, open wood lattice work, or insect screening intended to collapse
under wind and water loads without causing collapse, displacement,
or other structural damage to the elevated portion of the building
or supporting foundation system. For the purpose of this section,
a breakaway wall shall have a design safe-loading resistance of not
less than 10 and no more than 20 pounds per square foot. Use of breakaway
walls which exceed a design safe-loading resistance of 20 pounds per
square foot (either by design or when so required by local or state
codes) may be permitted only if a registered professional engineer
or architect certifies that the designs proposed meet the following
conditions:
(a)
Breakaway wall collapse shall result from a water load less
than which would occur during the base flood; and
(b)
The elevated portion of the building and supporting foundation
shall not be subject to collapse, displacement, or other structural
damage due to the effects of wind and water loads acting simultaneously
on all building components (structural and nonstructural). Water-loading
values used shall have a one-percent chance of being equaled or exceeded
in any given year. Wind-loading values used shall be those required
by applicable state or local building standards, but no less than
the one-percent annual chance values. Such enclosed space shall be
usable solely for parking of vehicles, building access or storage.
Such space shall not be partitioned into multiple rooms, temperature-controlled,
or used for human habitation.
(7)
All manufactured homes to be placed or substantially improved within V or VE Zones shall comply with the same standards as set forth for conventional housing in V or VE Zones and shall meet the standards for manufactured homes in § 76-14C(4).
(8)
Recreational vehicles. All recreational vehicles placed in V or VE
Zones must either:
(a)
Be on site for fewer than 180 consecutive days;
(b)
Be fully licensed and ready for highway use (A recreational
vehicle is ready for highway use if it is on its wheels or jacking
system, is attached to the site only by quick-disconnect-type utilities
and security devices, and has no permanently attached additions.);
or
(c)
Meet the same standards as for conventional housing in V or
VE Zones.
E.
Coastal A Zone District. Buildings and structures within this zone
shall have the lowest floor elevated two feet above the base flood
elevation and must comply with the standards of the Coastal High Hazard
District.
F.
Shallow Flooding District.
(1)
All new construction and substantial improvements of residential
structures shall have the lowest floor, including basement, elevated
to or above the flood depth specified on the FIRM, above the highest
adjacent grade, at least as high as the depth number specified in
feet on the FIRM. If no flood depth number is specified, the lowest
floor, including basement, shall be elevated no less than two feet
above the highest adjacent grade.
(2)
All new construction and substantial improvements of nonresidential
structures shall:
(a)
Have the lowest floor, including basement, elevated to or above
the flood depth specified on the FIRM, above the highest adjacent
grade, at least as high as the depth number specified in feet on the
FIRM. If no flood depth number is specified, the lowest floor, including
basement, shall be elevated at least two feet above the highest adjacent
grade; or
(b)
Together with attendant utility and sanitary facilities be completely
floodproofed to the specified flood level so that any space below
that level is 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.
(3)
Adequate drainage paths around structures on slopes shall be provided
to guide floodwaters around and away from proposed structures.
