The purpose of the FH Overlay District is to regulate the use
of those areas that are subject to periodic flooding in order to promote
the public health, safety, general welfare, and to minimize public
and private losses due to flood conditions. FEMA's FIRM map shows
the flood areas in Warrenton being in the FIRM category "A and AE"
in specific areas by provisions designed to:
A. Combine
with other zoning requirements, certain restrictions made necessary
for the known flood hazard areas to promote the general health, welfare
and safety of the City;
B. Protect
human life and health;
C. Prevent
the establishment of certain structures and land uses in areas unsuitable
for human habitation because of the danger of flooding, unsanitary
conditions or other hazards;
D. Minimize
expenditure of public money and costly flood control projects;
E. Minimize
the need for rescue and relief efforts associated with flooding and
generally undertaken at the expense of the general public;
F. Help
maintain a stable tax base by providing for the sound use and development
of areas of special flood hazard as to minimize future flood blight
areas;
G. Minimize
prolonged business interruptions;
H. Minimize
damage to public facilities and utilities such as water and gas mains,
electric, telephone and sewer lines, streets, and bridges located
in areas of special flood hazard;
I. Ensure
that potential buyers are notified that property is in an area of
special flood hazard; and
J. Ensure
that those who occupy the areas of special flood hazard assume responsibility
for their actions.
In all areas of special Flood Hazard Overlay Zone (FHO zone),
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 prevent flotation, collapse,
or lateral movement and shall be installed using methods and practices
that minimize flood damage. Anchoring methods may include, but are
not limited to, use of over-the-top and frame ties to ground anchors.
(Reference FEMA's "Manufactured Home Installation in Flood Hazard
Areas" guidebook for additional techniques.)
3. A
certificate signed by a registered architect or engineer which certifies
that the anchoring system is in conformance with FEMA regulations
shall be submitted prior to final inspection approval.
B. Construction
Materials and Methods.
1. All
new construction and substantial improvements shall be constructed
with materials and utility equipment resistant to flood damage.
2. All
new construction and substantial improvements shall be constructed
using methods and practices that minimize flood damage.
3. Electrical,
heating, ventilation, plumbing, and air conditioning equipment and
other service facilities shall be elevated or located so as to prevent
water from entering or accumulating within the components during conditions
of flooding.
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; and
3. On-site
waste disposal systems shall be located to avoid impairment of them
or contamination from them during flooding consistent with the Oregon
Department of Environmental Quality (DEQ).
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 or eliminate flood damage.
3. All
subdivision proposals shall have adequate drainage provided to reduce
exposure to flood damage.
4. Where
base flood elevation data has not been provided or is not available
from another authoritative source, it shall be generated for subdivision
proposals and other proposed developments which contain at least 50
lots or five acres (whichever is less).
E. Alteration
of Watercourses.
1. No
watercourse shall be altered until a maintenance plan is provided
which assures that the flood-carrying capacity of altered or relocated
portions of the watercourse is not diminished.
2. The
Community Development Director shall notify the Oregon Department
of Land Conservation and Development prior to any alteration or relocation
of a watercourse, and submit evidence of such notification to the
Federal Insurance Administration.
F. Review
of Building Permits. Where elevation data is not available either
through the Flood Insurance Study, FIRM, or from another authoritative
source, applications for building permits shall be reviewed to assure
that proposed construction will be reasonably safe from flooding.
The test of reasonableness is a local judgment and includes use of
historical data, high water marks, photographs of past flooding, etc.,
where available. Failure to elevate at least two feet above grade
in these zones may result in higher insurance rates.
G. Specific Standards, Residential and Nonresidential Construction. In all areas of special flood hazards (FH overlay district) where base flood elevation data has been provided as set forth in Section
16.88.020, the following provisions shall apply unless a variance is granted in accordance with Section
16.88.030 and Chapter
16.272.
1. Residential
Construction.
a. New construction and substantial improvement of any residential structure
shall have the lowest floor, including basement, elevated to a minimum
of one foot above the base flood elevation.
b. Fully enclosed areas below the lowest floor that are subject to flooding
are prohibited, or 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 be either
certified by a registered professional engineer, architect, or must
meet or exceed the following minimum criteria:
i. 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.
ii. The bottom of all openings shall be no higher than one foot above
grade.
iii.
Openings may be equipped with screens, louvers, or other coverings
or devices provided that they permit the automatic entry and exit
of floodwaters.
2. Nonresidential
Construction.
a. New construction and substantial improvement of any commercial, industrial,
or other nonresidential structure shall either have the lowest floor,
including basement, elevated to a minimum of one foot above the base
flood elevation; or, together with attendant utility and sanitary
facilities, shall:
i. Be floodproofed so that below the base flood level the structure
is watertight with walls substantially impermeable to the passage
of water;
ii. Have structural components capable of resisting hydrostatic and hydrodynamic
loads and effects of buoyancy;
iii.
Be 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 provisions of this subsection based on their development and/or review of the structural design, specification and plans. Such certifications shall be provided to the building official as set forth in Chapter
16.244;
iv. Nonresidential structures that are elevated, not floodproofed, must
meet the same standards for space below the lowest floor as described
in this section;
v. Applicants floodproofing nonresidential buildings shall be notified
that the flood insurance premiums will be based on rates that are
one foot below the floodproofed level (e.g., a building floodproofed
to the base flood level will be rated as one foot below).
b. Critical Facility. Construction of new critical facilities shall
be, to the extent possible, located outside the limits of the Special
Flood Hazard Area (SFHA) (100-year floodplain). Construction of new
critical facilities shall be permissible within the SFHA if no feasible
alternative site is available. Critical facilities constructed within
the SFHA shall have the lowest floor elevated three feet above BFE
or to the height of the 500-year flood, whichever is higher. Access
to and from the critical facility should also be protected to the
height utilized above. Floodproofing and sealing measures must be
taken to ensure that toxic substances will not be displaced by or
released into floodwaters. Access routes elevated to or above the
level of the base flood elevation shall be provided to all critical
facilities to the extent possible.
H. Manufactured
Homes/Dwellings.
1. All
manufactured homes to be placed or substantially improved on sites:
a. Outside of a manufactured home park or subdivision;
b. In a new manufactured home park or subdivision;
c. In an expansion to an existing manufactured home park or subdivision;
or
d. In an existing manufactured home park or subdivision on which a manufactured
home has incurred "substantial damage" shall be elevated on a permanent
foundation such that the finished floor of the manufactured home is
elevated to a minimum 18 inches (46 cm)* above the base flood elevation,
is securely anchored to an adequately designed foundation system to
resist flotation, collapse and lateral movement, and electrical crossover
connections are a minimum of 12 inches above BFE.
2. Manufactured
homes to be placed or substantially improved on sites in an existing
manufactured home park or subdivision within Zones Al-30, AH, and
AE on the community's FIRM that are not subject to the above manufactured
home provisions shall be elevated so that either:
a. The lowest floor of the manufactured home is elevated to a minimum
of 18 inches (46 cm) above the base flood elevation; or
b. 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 be securely anchored
to an adequately designed foundation system to resist flotation, collapse,
and lateral movement.
* See 2002 Oregon Manufactured Dwelling and Parks Specialty
Code, Chapter 3. The code also requires that the top of the dwelling
stand be at least 12 inches above BFE.
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I. Specific
Standards, Manufactured Dwelling Parks or Subdivisions.
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. Where
base flood elevation data has not been provided or is not available
from another authoritative source, it shall be generated for subdivision
proposals and other proposed developments which contain at least 50
lots or five acres (whichever is less).
J. Recreational
Vehicles. Recreational vehicles placed on sites are required to either:
1. Be
on the site for fewer than 180 consecutive days;
2. Be
fully licensed and ready for highway use, 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
3. Meet
the requirements in Section 16.88.030(B)(9), and the elevation and
anchoring requirements for manufactured homes.
K. Review
of Flood Hazard Permits. Where elevation data is not available either
through the Flood Insurance Study or from another authoritative source,
applications for building permits shall be reviewed to assure that
proposed construction will be reasonably safe from flooding. The test
of reasonableness is a local judgment and includes use of historical
data, high water marks, photographs of past flooding, etc., where
available. Failure to elevate at least two feet above grade in these
zones may result in higher insurance rates.
L. Flood Hazard, Park and Open Space Dedications. Where fill and/or development is allowed within or adjacent to the 100-year floodplain outside the zero-foot rise floodplain, and the Comprehensive Plan designates the subject floodplain for park, open space, or trail use, the City may require the dedication of sufficient open land area for a greenway adjoining or within the floodplain. When practicable, this area shall include portions at a suitable elevation for the construction of a pedestrian/bicycle pathway within the floodplain in accordance with the City's adopted TSP for trails, pedestrian, and bikeway, as applicable. The City shall evaluate individual development proposals and determine whether the dedication of land is justified based on the development's impact and shall be consistent with Chapter
16.136.
M. Temporary
Encroachments in the Floodway for the Purposes of Bridge Construction
and Repair.
1. This use shall comply with this chapter, Section
16.208.040 (Type II Procedure), and Chapter
16.240 (Miscellaneous Permits) prior to issuance of any permits.
2. The
temporary permit shall state the number of days the structure or other
development will be on the site. If a longer period is required, a
new permit shall be issued.
3. A
flood warning system for the project should be in place to allow equipment
to be evacuated from the site and placed outside the floodplain.
4. Placement
of equipment in the floodway should be restricted to only equipment
which is absolutely necessary for the purposes of the project. All
other accessory equipment and temporary structures (i.e., construction
trailers) should be restricted from the floodway. Structures should
be placed on site so that flood damages are minimized. Anchoring the
construction trailers in case evacuation is not practical.
N. Coastal High Hazard Areas. Located within areas of special flood hazard established in Section
16.88.030(B) are Coastal High Hazard Areas, designated as Zones V1-V30, VE and/or V. These areas have special flood hazards associated with high velocity waters from surges and, therefore, in addition to meeting all provisions in this title the following provisions shall also apply:
1. All
new construction and substantial improvements in Zones V1-V30 and
VE (V if base flood elevation data is available) shall be elevated
on pilings and columns so that:
a. The bottom of the lowest horizontal structural member of the lowest
floor (excluding the pilings or columns) is elevated a minimum of
one foot above the base flood level; and
b. The pile or column foundation and structure attached thereto is anchored
to resist flotation, 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 (100-year mean recurrence
interval);
2. A
registered professional engineer or architect shall develop or review
the structural design, specifications and plans for the construction,
and shall certify that the design and methods of construction to be
used are in accordance with accepted standards of practice for meeting
the provisions of paragraphs (a) and (b) of this subsection.
3. Obtain
the elevation (in relation to mean sea level) of the bottom of the
lowest structural member of the lowest floor (excluding pilings and
columns) of all new and substantially improved structures in Zones
V1-30, VE, and V, and whether or not such structures contain a basement.
The local administrator shall maintain a record of all such information.
4. All
new construction shall be located landward of the reach of mean high
tide.
5. Provide
that all new construction and substantial improvements have the space
below the lowest floor either free of obstruction or constructed with
non-supporting 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 water load less than that
which would occur during the base flood; and
b. The elevated portion of the building and supporting foundation system
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). Maximum
wind and water loading values to be used in this determination shall
each have a one percent chance of being equaled or exceeded in any
given year (100-year mean recurrence interval).
6. If
breakaway walls are utilized, such enclosed space shall be useable
solely for parking of vehicles, building access, or storage. Such
space shall not be used for human habitation.
7. Prohibit
the use of fill for structural support of buildings.
8. Prohibit
man-made alteration of sand dunes which would increase potential flood
damage.
9. All
manufactured homes to be replaced or substantially improved within
Zones V1-V30, V, and VE on the community's FIRM shall meet the standards
of paragraphs (1) through (8) of this subsection.
10. Recreational vehicles placed on sites within Zones V1-30, V, and
VE on the community's FIRM either:
a. Be on the site for fewer than 180 consecutive days;
b. Be fully licensed and ready for highway use, 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 requirements of Section
16.88.030(A) and paragraphs (1) through (8) of this subsection.
(Ord. 1175-A § 11, 2013; Ord. 1220 §§ 3, 4, 2018)