CHAPTER 10 Title 7 Flood Plain Requirements
CHAPTER 10
FLOODPLAIN REQUIREMENTS
7-10-1: Statement of Purpose
7-10-2: Definitions
7-10-3: General Provisions
7-10-4: Administration
7-10-5: Provisions for Flood Hazard Protection
7-10-6: Minimum Flood Proof Basement Design
7-10-7: Accessory Structures
7-10-8: Flood Insurance Study
STATUTORY AUTHORITY:
The Legislature of the State of Idaho, pursuant to Idaho Code §§ 46-1020, 46-1023, and 46-
1024, authorizes local governments to adopt floodplain management ordinances that identify
floodplains and minimum floodplain development standards to minimize flood hazards and
protect human life, health, and property. Therefore, the Council of the City of Ammon, Idaho
does hereby ordain as follows:
7-10-1: STATEMENT OF PURPOSE:
(A) The purpose of this ordinance is to promote public health, safety, and general welfare and to
minimize public and private losses due to flood conditions in specific areas by provisions
designed to:
1. Protect human life, health, and property;
2. Minimize damage to public facilities and utilities such as water purification and
sewage treatment plants, water and gas mains, electric, telephone and sewer lines,
streets, and bridges located in floodplains;
3. Help maintain a stable tax base by providing for the sound use and development
of flood prone areas;
4. Minimize expenditure of public money for costly flood control projects;
5. Minimize the need for rescue and emergency services associated with flooding,
generally undertaken at the expense of the general public;
6. Minimize prolonged business interruptions;
7. Ensure potential buyers are notified the property is in an area of special flood
hazard; and
8. Ensure those who occupy the areas of special flood hazard assume responsibility
for their actions.
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(B) Findings of Fact
1. The flood hazard areas of the City of Ammon are subject to periodic inundation which results
in loss of life and property, health and safety hazards, disruption of commerce and governmental
services, extraordinary public expenditures for flood protection and relief, and impairment of the
tax base, all of which adversely affect the public health, safety, and general welfare.
2. These flood losses are caused by development in flood hazard areas, which are inadequately
elevated, flood-proofed, or otherwise unprotected from flood damages, and by the cumulative
effect of obstructions in areas of special flood hazards which increase flood heights and
velocities, and when inadequately anchored, damage uses in other areas. Uses that are
inadequately floodproofed, elevated, or otherwise protected from flood damage also contribute to
the flood loss.
3. Local government units have the primary responsibility for planning, adopting, and enforcing
land use regulations to accomplish proper floodplain management.
(C). Objectives and Methods of Reducing Flood Losses
In order to accomplish its purpose, this ordinance includes methods and provisions to:
1. Require that development which is vulnerable to floods, including structures and facilities
necessary for the general health, safety, and welfare of citizens, be protected against flood
damage at the time of initial construction;
2. Restrict or prohibit development which are dangerous to health, safety, and property due to
water or erosion hazards, or which increase flood heights, velocities, or erosion;
3. Control filling, grading, dredging, and other development which may increase flood damage
or erosion;
4. Prevent or regulate the construction of flood barriers that will unnaturally divert flood waters
or that may increase flood hazards to other lands;
5. Preserve and restore natural floodplains, stream channels, and natural protective barriers
which carry and store flood waters.
7-10-2: DEFINITIONS: Unless specifically defined below, words or phrases used in this
chapter shall be interpreted so as to give them the meaning they have in common usage and to
give this chapter it’s most reasonable application.
ACCESSORY AND AGRICULTURAL STRUCTURES (APPURTENANT STRUCTURE): a
structure on the same lot or parcel as a principal structure, the use of which is incidental and
subordinate to the principal structure.
ADDITION (TO AN EXISTING BUILDING): an extension or increase in the floor area or
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height of a building or structure.
AGRICULTURAL STRUCTURES (APPURTENANT STRUCTURE): a structure which is
used exclusively in connection with the production, harvesting, storage, raising, or drying of
agricultural commodities and livestock; specifically excludes any structures used for human
habitation.
APPEAL: A request for a review of the City of Ammon’s interpretation of any provision of this
chapter or a request for a variance.
AREA OF SHALLOW FLOODING: A designated AO or AH Zone on the Flood Insurance Rate
Map (FIRM). The base flood depths range from one to three feet; a clearly defined channel does
not exist; the path of flooding is unpredictable and indeterminate; and velocity flow may be
evident. AO is characterized as sheet flow and AH indicates ponding.
AREA OF SPECIAL FLOOD HAZARD: The land in the floodplain within a community
subject to
a one percent or greater chance of flooding in any given year. Designation on maps always
includes the letters A or V.
BASE FLOOD: The flood having a one percent (1%) chance of being equaled or exceeded in
any given year. Also referred to as the “100-year flood.” Designation on maps always includes
the letters A or V.
BASE FLOOD ELEVATION (BFE): a determination by the Federal Insurance Administrator of
the water surface elevations of the base flood, that is, the flood level that has a one percent or
greater chance of occurrence in any given year. When the BFE has not been provided in a
Special Flood Hazard Area, it may be obtained from engineering studies available from a
Federal, State, or other source using FEMA-approved engineering methodologies. This
elevation, when combined with the Freeboard, establishes the Flood Protection Elevation.
BASEMENT: any area of the building having its floor sub grade (below ground level) on all
sides.
BUILDING: see Structure.
CLEANING (IRRIGATION): mowing, cutting, or burning of weeds, trees and other nuisance
growth, including algae growth, application of pesticides as permitted, removal of beaver dams,
and removal of trash or other debris whether floating, lodged or otherwise obstructing the
conveyance of water flow through channels and works.
CRITICAL FACILITIES: facilities that are vital to flood response activities or critical to the
health and safety of the public before, during, and after a flood, such as a hospital, emergency
operations center, electric substation, police station, fire station, nursing home, school, vehicle
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and equipment storage facility, or shelter; and facilities that, if flooded, would make the flood
problem and its impacts much worse, such as a hazardous materials facility, power generation
facility, water utility, or wastewater treatment plant.
DATUM: the vertical datum is a base measurement point (or set of points) from which all
elevations are determined. Historically, that common set of points was the National Geodetic
Vertical Datum of 1929 (NGVD29). The vertical datum currently adopted by the federal
government as a basis for measuring heights is the North American Vertical Datum of 1988
(NAVD88)
DEVELOPMENT: Any man-made change to improved or unimproved real estate, including but
not limited to buildings or other structures, mining, dredging, filling, grading, paving,
excavation, or drilling operations located within the area of special flood hazard.
DEVELOPMENT ACTIVITY: any activity defined as Development which will necessitate a
Floodplain Development Permit; such as: the construction of buildings, structures, or accessory
structures; additions or substantial improvements to existing structures; bulkheads, retaining
walls, piers, and pools; the placement of mobile homes; or the deposition or extraction of
materials; the construction or elevation of dikes, berms and levees.
DIGITAL FLOOD INSURANCE RATE MAP (DFIRM): the digital official map of a
community, issued by the Federal Insurance Administrator, on which both the Special Flood
Hazard Areas and the risk premium zones applicable to the community are delineated.
ELEVATED BUILDING: for insurance purposes, a non-basement building which has its lowest
elevated floor raised above ground level by foundation walls, shear walls, posts, piers, pilings, or
columns.
ELEVATION CERTIFICATE: The Elevation Certificate is an important administrative tool of
the NFIP. It is used to determine the proper flood insurance premium rate; it is used to document
elevation information; and it may be used to support a request for a Letter of Map Amendment
(LOMA) or Letter of Map Revision based on fill (LOMR-F).
ENCLOSURE: an area enclosed by solid walls below the BFE/FPE or an area formed when any
space below the BFE/FPE is enclosed on all sides by walls or partitions. Insect screening or open
wood lattice used to surround space below the BFE/RFPE is not considered an enclosure.
ENCROACHMENT: the advance or infringement of uses, fill, excavation, buildings, structures,
or development into a floodplain, which may impede or alter the flow capacity of a floodplain.
EXISTING CONSTRUCTION: for the purposes of determining rates, structures for which the
“start of construction” commenced before the effective date of the FIRM or before January 1,
1975, for FIRMs effective before that date. “Existing construction” may also be referred to as
“existing structures.”
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EXISTING MANUFACTURED HOME PARK OR MANUFACTURED HOME
SUBDIVISION: a manufactured home park or subdivision where the construction of facilities
for servicing the lots on which the manufactured homes are to be affixed (including, at a
minimum, the installation of utilities, the construction of streets, and final site grading or the
pouring of concrete pads) is completed before the effective date of the original floodplain
management regulations adopted by the community, July 15, 1982.
EXISTING STRUCTURES: see existing construction.
EXPANSION TO AN EXISTING MANUFACTURED HOME PARK OR SUBDIVISION: the
preparation of additional sites by the construction of facilities for servicing the lots on which the
manufacturing homes are to be affixed (including the installation of utilities, the construction of
streets, and either final site grading or the pouring of concrete pads).
FLOOD or FLOODING: (a) A general and temporary condition of partial or complete
inundation of normally dry land areas from (1) the overflow of inland or tidal waters and/or (2)
the unusual and rapid accumulation of runoff of surface waters from any source. (3) Mudslides
(i.e., mudflows) which are approximately caused by flooding as defined in paragraph a.2. of this
definition and are akin to a river of liquid and flowing mud on the surfaces of normally dry land
areas, as when earth is carried by a current of water and deposited along the path of the current.
(b) The collapse or subsidence of land along the shore of a lake or other body of water as a result
of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical
levels or suddenly caused by an unusually high water level in a natural body of water,
accompanied by a severe storm, or by an unanticipated force of nature, such as flash flood or an
abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in
flooding as defined in paragraph a.1. of this definition.
FLOOD BOUNDARY AND FLOODWAY MAP (FBFM): The FBFM shows how the
floodplain is divided into the floodway and flood fringe where streams are studied in detail. They
also show general floodplain areas where floodplains have been studied by approximate
methods. (Old format Pre-1986)
FLOOD ELEVATION DETERMINATION: See Base Flood Elevation (BFE)
FLOOD ELEVATION STUDY: See Flood Insurance Study (FIS)
FLOOD HAZARD BOUNDARY MAP (FHBM): an official map of a community, issued by the
Federal Insurance Administrator, where the boundaries of the flood, mudslide (i.e., mudflow)
related erosion areas having special hazards have been designated as Zones A, M, and/or E.
FLOOD INSURANCE RATE MAP (FIRM): The official map on which the Federal Insurance
Administration has delineated both the areas of special flood hazards and the risk premium zones
applicable to the community.
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FLOOD INSURANCE STUDY: The official report provided by the Federal Insurance
Administration that includes flood profiles, the Flood Boundary-Floodway Map, and the water
surface elevation of the base flood.
FLOOD ZONE: a geographical area shown on a Flood Hazard Boundary Map (FHBM) or Flood
Insurance Rate Map (FIRM) that reflects the severity or type of flooding in the area, and
applicable insurance rate.
FLOODPLAIN OR FLOOD-PRONE AREA: any land area susceptible to being inundated by
water from any source (see definition of “flooding”).
FLOODPLAIN ADMINISTRATOR: the individual appointed to administer and enforce the
floodplain management regulations.
FLOODPLAIN DEVELOPMENT PERMIT: any type of permit that is required in conformance
with the provisions of this ordinance, prior to the commencement of any development activity.
FLOODPLAIN MANAGEMENT: the operation of an overall program of corrective and
preventive measures for reducing flood damage, including but not limited to emergency
preparedness plans, flood control works, and floodplain management regulations.
FLOODPLAIN MANAGEMENT REGULATIONS: zoning ordinances, subdivision regulations,
building codes, health regulations, special purpose ordinances (such as a floodplain ordinance,
grading ordinance, and erosion control ordinance), and other applications of police power. The
term describes such state or local regulations, in any combination thereof, which provide
standards for the purpose of flood damage prevention and reduction.
FLOODPROOFING: any combination of structural and non-structural additions, changes, or
adjustments to structures which reduce or eliminate flood damage to real estate or improved real
property, water and sanitary facilities, structures and their contents.
FLOOD PROTECTION ELEVATION (FPE): The Base Flood Elevation plus the Freeboard.
• In “Special Flood Hazard Areas” where Base Flood Elevations (BFEs) have been
determined, this elevation shall be the BFE plus 2 feet of freeboard; and
• In “Special Flood Hazard Areas” where no BFE has been established, this
elevation shall be at least 2 feet above the highest adjacent grade.
FLOOD PROTECTION SYSTEM: those physical structural works for which funds have been
authorized, appropriated, and expended and which have been constructed specifically to modify
flooding in order to reduce the extent of the area within a community subject to a “special flood
hazard” and the extent of the depths of associated flooding. Such a system typically includes
dams, reservoirs, levees, or dikes. These specialized flood modifying works are those constructed
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in conformance with sound engineering standards.
FLOODWAY: The channel of a river or other watercourse and the adjacent land areas that must
be reserved in order to discharge the base flood without cumulatively increasing the water
surface elevation more than one foot.
FREEBOARD: a factor of safety usually expressed in feet above a flood level for the purposes of
floodplain management. Freeboard tends to compensate for the many unknown factors that could
contribute to flood heights greater than the height calculated for a selected size flood and
floodway conditions, such as wave action, obstructed bridge openings, debris and ice jams, and
the hydrologic effects of urbanization in a watershed. The Base Flood Elevation (BFE) plus the
freeboard establishes the Flood Protection Elevation (FPE). Freeboard shall be 2 feet.
FUNCTIONALLY DEPENDENT USE: a facility that cannot be used for its intended purpose
unless it is located or carried out in close proximity to water, such as a docking or port facility
necessary for the loading and unloading of cargo or passengers, shipbuilding, or ship repair
facilities. The term does not include long-term storage, manufacture, sales, or service facilities.
GENERAL IRRIGATION FLOODPLAIN DEVELOPMENT PERMIT (GIFD PERMIT): The
intent of the GIFD permit is to collectively authorize low-to-no impact irrigation and drainage
development activities or uses in the floodplain which inherently do not increase the BFE. GIFD
permits apply to all qualifying activities within the spatial extents of an irrigation delivery or
drainage system and within the regulatory floodway or SFHA, over a predetermined period of
time, not to exceed five years. Issuance of a GIFD permit requires coordination between the
irrigation entity and the Floodplain Administrator.
HIGHEST ADJACENT GRADE (HAG): the highest natural elevation of the ground surface
prior to construction, adjacent to the proposed walls of a structure. Refer to the FEMA Elevation
Certificate for HAG related to building elevation information.
HISTORIC STRUCTURE: a structure that is:
a. Listed individually in the National Register of Historic Places (a listing maintained by the
U.S. Department of Interior) or preliminarily determined by the Secretary of the Interior as
meeting the requirements for individual listing on the National Register;
b. Certified or preliminarily determined by the Secretary of the Interior as contributing to
the historical significance of a registered historic district or to a district preliminarily
determined by the Secretary to qualify as a registered historic district;
c. Individually listed on a state inventory of historic places and determined as eligible by
states with historic preservation programs which have been approved by the Secretary of the
Interior; or
d. Individually listed on a local inventory of historic places and determined as eligible by
communities with historic preservation programs that have been certified either:
1. by an approved state program as determined by the Secretary of the Interior, or
2. directly by the Secretary of the Interior in states without approved programs.
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LETTER OF MAP CHANGE (LOMC): a general term used to refer to the several types of
revisions and amendments to FIRMs that can be accomplished by letter. They include Letter of
Map Amendment (LOMA), Letter of Map Revision (LOMR), and Letter of Map Revision based
on Fill (LOMR-F)
LETTER OF MAP AMENDMENT (LOMA): an official amendment, by letter, to an effective
National Flood Insurance Program (NFIP) map. A LOMA establishes a property’s or structure’s
location in relation to the Special Flood Hazard Area (SFHA). LOMAs are usually issued
because a property or structure has been inadvertently mapped as being in the floodplain but is
actually on natural high ground above the base flood elevation.
LETTER OF MAP REVISION (LOMR): FEMA's modification to an effective Flood Insurance
Rate Map (FIRM) or a Flood Boundary and Floodway Map (FBFM) or both. LOMRs are
generally based on the implementation of physical measures that affect the hydrologic or
hydraulic characteristics of a flooding source and thus result in the modification of the existing
regulatory floodway, the effective Base Flood Elevations (BFEs), or the Special Flood Hazard
Area (SFHA). The LOMR officially revises the Flood Insurance Rate Map (FIRM) or Flood
Boundary and Floodway Map (FBFM), and sometimes the Flood Insurance Study (FIS) report,
and when appropriate, includes a description of the modifications. The LOMR is generally
accompanied by an annotated copy of the affected portions of the FIRM, FBFM, or FIS report.
LETTER OF MAP REVISION BASED ON FILL (LOMR-F): FEMA's modification of the
Special Flood Hazard Area (SFHA) shown on the Flood Insurance Rate Map (FIRM) based on
the placement of fill outside the existing regulatory floodway. The LOMR-F does not change the
FIRM, FBFM, or FIS report.
CONDITIONAL LETTER OF MAP REVISION (CLOMR): A formal review and comment as
to whether a proposed flood protection project or other project complies with the minimum NFIP
requirements for such projects with respect to delineation of special flood hazard areas. A
CLOMR does not revise the effective Flood Insurance Rate Map (FIRM) or Flood Insurance
Study (FIS). Upon submission and approval of certified as-built documentation, a Letter of Map
Revision (LOMR) may be issued by FEMA to revise the effective FIRM. Building Permits
and/or Flood Development Permits cannot be issued based on a CLOMR, because a CLOMR
does not change the NFIP map.
LEVEE: a man-made structure, usually an earthen embankment, designed and constructed
according to sound engineering practices, to contain, control, or divert the flow of water so as to
provide protection from temporary flooding.
LEVEE SYSTEM: a flood protection system that consists of a levee, or levees, and associated
structures, such as closure and drainage devices, which are constructed and operated in
accordance with sound engineering practices.
LOWEST ADJACENT GRADE (LAG): the lowest point of the ground level next to the
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structure. Refer to the FEMA Elevation Certificate for LAG related to building elevation
information.
LOWEST FLOOR: The lowest floor of the lowest enclosed area (including basement). An
unfinished or flood resistance enclosure, usable solely for parking of vehicles, building access, or
storage, in an area other than a basement area, is not considered a building’s lowest floor,
provided that such enclosure is not built so as to render the structure in violation of the
applicable non-elevation design requirements of this chapter found at Section 7-10-5 (B)
1(b).
MAINTENANCE (IRRIGATION): the act of ongoing upkeep of existing structures required to
keep channels in a condition adequate to support the conveyance of irrigation and drainage water
(this does not include the complete replacement or substantial replacement of an existing
structure). Maintenance is further defined as the care or upkeep of channels, works,
appurtenances, easements, utility corridors and property; to keep in an existing state, specified
state of repair, and efficiency; return to a former condition, elevation, place, and position; to
preserve from failure or decline; or repair or renovate so as to return it to its original condition.
Maintenance does not include dredging as defined herein.
MANUFACTURED HOME: A structure, transportable in one or more sections, which is built
on a permanent chassis and is designed for use with or without a permanent foundation when
connected to the required utilities. For floodplain management purposes the term “manufactured
home” also includes park trailers, travel trailers, and other similar vehicles placed on a site for
greater than 180 consecutive days. For insurance purposes the term “manufactured home” does
not include park trailers, travel trailers, and other similar vehicles.
MANUFACTURED HOME PARK OR SUBDIVISION: A parcel (or contiguous parcels) of
land divided into two (2) or more manufactured home lots for rent or sale.
MARKET VALUE: the building value, not including the land value and that of any accessory
structures or other improvements on the lot. Market value may be established by independent
certified appraisal; replacement cost depreciated for age of building and quality of construction
(Actual Cash Value); or adjusted tax assessed values.
MEAN SEA LEVEL: for purposes of the National Flood Insurance Program (NFIP), the
National Geodetic Vertical Datum (NGVD) of 1929 or other datum (such as North America
Vertical Datum of 1988 - NAVD88) to which Base Flood Elevations (BFEs) shown on a
community’s FIRM are referenced.
MUDSLIDE (I.E., MUDFLOW): describes a condition where there is a river, flow, or
inundation of liquid mud down a hillside usually as a result of a dual condition of loss of brush
cover and the subsequent accumulation of water on the ground preceded by a period of unusually
heavy or sustained rain. A mudslide (i.e., mudflow) may occur as a distinct phenomenon while a
landslide is in progress, and will be recognized as such by the Administrator only if the mudflow,
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and not the landslide, is the proximate cause of damage that occurs.
MUDSLIDE (I.E., MUDFLOW) AREA MANAGEMENT: the operation of an overall program
of corrective and preventive measures for reducing mudslide (i.e., mudflow) damage, including
but not limited to emergency preparedness plans, mudslide control works, and floodplain
management regulations.
MUDSLIDE (I.E., MUDFLOW) PRONE AREA: an area with land surfaces and slopes of
unconsolidated material where the history, geology, and climate indicate a potential for
mudflow.
NATIONAL FLOOD INSURANCE PROGRAM (NFIP): The NFIP is a Federal program
created by Congress to mitigate future flood losses nationwide through sound, community-
enforced building and zoning ordinances and to provide access to affordable, federally backed
flood insurance protection for property owners.
NEW CONSTRUCTION: Structures for which the “start of construction” commenced on or
after the effective date of this chapter. Any construction started after July 15, 1982 and before
the effective start date of this floodplain management ordinance is subject to the ordinance in
effect at the time the permit was issued, provided the start of construction was within 180 days of
permit issuance.
RECREATIONAL VEHICLE: a vehicle that is:
a. Built on a single chassis, and
b. 400 square feet or less when measured at the largest horizontal projection, and
c. Designed to be self-propelled or permanently towed by a light duty truck, and
d. Designed primarily not for use as a permanent dwelling but as temporary living
quarters for recreational, camping, travel, or seasonal use.
REGULATORY FLOODWAY: See Floodway
REMEDY A VIOLATION: to bring the structure or other development into compliance with
State or local floodplain management regulations, or, if this is not possible, to reduce the impacts
of its non-compliance. Ways that impacts may be reduced include protecting the structure or
other affected development from flood damages, implementing the enforcement provisions of the
ordinance or otherwise deterring future similar violations, or reducing Federal financial exposure
with regard to the structure or other development.
REPAIR (IRRIGATION): the restoration to good or sound conditions of any part of an existing
structure, channel, channel bank, or service road for the purpose of maintenance (this does not
include the complete replacement or substantial replacement of an existing structure). Repair
does not include dredging as defined herein.
REPETITIVE LOSS STRUCTURE: An NFIP-insured structure that has had at least two paid
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flood losses of more than $1,000 each in any 10-year period since 1978.
RIVERINE: relating to, formed by, or resembling a river (including tributaries), stream, brook,
etc.
SPECIAL FLOOD HAZARD AREA (SFHA): the land in the floodplain within a community
subject to a one percent (1%) or greater chance of flooding in any given year. For purposes of
these regulations, the term “special flood hazard area” is synonymous in meaning with the phrase
“area of special flood hazard”
START OF CONSTRUCTION: Includes substantial improvement and means the date the
building permit was issued, provided the actual start of construction, repair, reconstruction,
placement, or other improvement was within 180 days of the permit date. The actual start means
either the first placement of permanent construction of a structure on a site, such as the pouring
of slabs or footings, the installation of piles, the construction of columns, or any work beyond the
stage of excavation; or the placement of a manufactured home on a foundation. Permanent
construction does not include land preparation such as clearing, grading, and filling; nor does it
include the installation of streets and/or walkways; nor does it include excavation for a basement,
footing, piers, or foundations or the erection of temporary forms; nor does it include the
installation on the property of accessory buildings such as garages or sheds not occupied as
dwelling units or not as part of the main structure. For a substantial improvement, the actual start
of construction means the first alteration of any wall, ceiling, floor, or other structural part of a
building, whether or not that alteration affects the external dimensions of the building.
STRUCTURE: A walled and roofed building, including a gas or liquid storage tank that is
principally above ground, as well as a manufactured home.
SUBSTANTIAL DAMAGE: damage of any origin sustained by a structure whereby the cost of
restoring the structure to its before-damaged condition would equal or exceed 50 percent (50%)
of its market value before the damage occurred. See definition of “substantial improvement”
SUBSTANTIAL IMPROVEMENT: Any repair, reconstruction, or improvement of a structure,
the cost of which equals or exceeds fifty percent (50%) of the market value of the structure
before the “start of construction” of the improvement. This term includes structures which have
incurred “substantial damage”, regardless of the actual repair work performed. The term does
not, however, include either:
• Any project for improvement of a structure to correct existing violations of state
or local health, sanitary, or safety code specifications which have been identified by the
local code enforcement official and which are the minimum necessary to assure safe
living conditions; or
• Any alteration of a “historic structure”, provided that the alteration will not
preclude the structure's continued designation as a “historic structure” and the alteration
is approved by variance issued pursuant to this ordinance
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TECHNICAL BULLETINS AND TECHNICAL FACT SHEETS: FEMA publications that
provide guidance concerning the building performance standards of the NFIP, which are
contained in Title 44 of the U S Code of Federal Regulations § 60.3. The bulletins and fact sheets
are intended for use primarily by State and local officials responsible for interpreting and
enforcing NFIP regulations and by members of the development community, such as design
professionals and builders. New bulletins, as well as updates of existing bulletins, are issued
periodically as needed. The bulletins do not create regulations. Rather they provide specific
guidance for complying with the minimum requirements of existing NFIP regulations.
It should be noted that Technical Bulletins and Technical Fact Sheets provide guidance on the
minimum requirements of the NFIP regulations. State or community requirements that exceed
those of the NFIP take precedence. Design professionals should contact the community officials
to determine whether more restrictive State or local regulations apply to the building or site in
question. All applicable standards of the State or local building code must also be met for any
building in a flood hazard area.
TEMPERATURE CONTROLLED: having the temperature regulated by a heating and/or
cooling system, built-in or appliance.
VARIANCE: A grant of relief from the requirements of this chapter which permits construction
in a manner that would otherwise be prohibited by this chapter.
VIOLATION: the failure of a structure or other development to be fully compliant with the
community's floodplain management regulations. A structure or other development without the
Finished Construction Elevation Certificate, other certifications, or other evidence of compliance
required in 44 CFR § 60.3(b)(5), (c)(4), (c) (10), (d)(3), (e)(2), (e)(4), or (e)(5) is presumed to be
in violation until such time as that documentation is provided.
WATER SURFACE ELEVATION: the height, in relation to the National Geodetic Vertical
Datum (NGVD) of 1929 or the North American Vertical Datum (NAVD) of 1988 (or other
specified datum), of floods of various magnitudes and frequencies in the flood plains of coastal
or riverine areas.
WATERCOURSE: a lake, river, creek, stream, wash, channel, or other topographic feature on or
over which waters flow at least periodically. Watercourse includes specifically designated areas
in which substantial flood damage may occur.
7-10-3: GENERAL PROVISIONS:
(A) Lands to Which This Chapter Applies: This chapter shall apply to all areas of special
flood hazards within the jurisdiction of the City of Ammon. Nothing in this ordinance is
intended to allow uses or structures that are otherwise prohibited by the zoning ordinance.
(B) Basis for Establishing the Areas of Special Flood Hazard: The areas of special flood
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hazard identified by the Federal Insurance Administration in a scientific and engineering
report entitled “The Ammon Flood Insurance Study and Maps for Ammon, Idaho,” dated
July 19, 1982, with accompanying Flood Insurance Rate Maps (FIRM) is hereby adopted
by this reference and declared to be a part of this chapter. The Flood Insurance Study is
on file at City Hall, City of Ammon, 2135 South Ammon Road, Idaho 83406.
(C) Penalties for Noncompliance: No structure of land shall hereafter be constructed,
located, extended, converted, or altered without full compliance with the terms of this
chapter and other applicable regulations. Violation of the provisions of this chapter by
failure to comply with any of its requirements (including violation of conditions and
safeguards established in connection with conditions) shall constitute a misdemeanor.
Any person who violates this ordinance or fails to comply with any of its requirements
shall upon conviction thereof be fined not more than Three Hundred Dollars ($300) or
imprisoned for not more than ninety (90) days, or both, for each violation, and in addition
shall pay all costs and expenses involved in the case. Nothing herein contained shall
prevent the City of Ammon from taking such other lawful action as is necessary to
prevent or remedy any violation.
(D) Abrogation and Greater Restrictions: This chapter is not intended to repeal, abrogate,
or impair any existing easements, covenants, or deed restrictions. However, where this
chapter and another chapter, ordinance, easement, covenant, or deed restriction conflict
or overlap, whichever imposes the more stringent restrictions shall prevail.
(E) Interpretation: In the interpretation and application of this chapter, all provisions shall
be:
1. Considered as minimum requirements;
2. Liberally construed in favor of the governing body; and
3. Deemed neither to limit nor repeal any other powers granted under state
statutes.
(F) Warning and Disclaimer of Liability: The degree of flood protection required by this
chapter is considered reasonable for regulatory purposes and is based on scientific and
engineering considerations. Larger floods can and will occur on rare occasions. Flood
heights may be increased by man-made or natural causes. This chapter does not imply
that land outside the areas of special flood hazards or uses permitted within such areas
will be free from flooding or flood damages. This chapter shall not create liability on the
part of the City of Ammon, any officer or employee thereof, or the Federal Insurance
Administration for any flood damages that result from reliance on this chapter or any
administrative decision lawfully made hereunder.
7-10-4: ADMINISTRATION
Title 7, Chapter 10 Page 13 of 39 Revised 2-2021
(A) Establishment of Development Permit: A development permit shall be obtained
before construction or development begins within any area of special flood hazard
established in Section 7-10-3-(B) above. The permit shall be for all structures including
manufactured homes, as set forth in Section 7-10-2, Definitions, and for all other
development including fill and other activities, also as set forth in Section 7-10-2,
Definitions.
(B) Designation of the Local Administrator: The City of Ammon City Engineer is hereby
appointed to administer and implement this chapter by granting or denying development
permit applications in accordance with its provisions.
(C) Duties and Responsibilities of the Local Administrator: Duties of the City Engineer
shall include, but not be limited to:
1. Permit Review:
(a) Review all development permits to determine that the permit
requirements of this chapter have been satisfied.
(b) Review all development permits to determine that all necessary permits
have been obtained from those federal, state, or local governmental agencies
from which prior approval is required.
(c) Review all development permits to determine if the proposed
development is located in the floodway. If located in the floodway, assure
that the encroachment provisions of Section 7-10-5(C) 1 are met.
2. Use of Other Flood Data: When base flood elevation and floodway data have not
been provided in accordance with Section 7-10-3(B), Basis for Establishing the
Areas of Special Flood Hazard, the City Engineer shall obtain, review, and
reasonably utilize any base flood elevation and floodway data available from a
federal, state, or source, in order to administer Section 7-10-5(B)1, Specific
Standards, Residential Construction, Section 7-10-5(B)2, Specific Standards,
Nonresidential Construction, and Section 7-10-5(C), Floodways.
3. Information to be Obtained and Maintained:
(a) Where base flood elevation data is provided through the Flood Insurance
Study or required as in Section 7-10-4(C)2, obtain and record the actual
elevation (in relation to mean sea level) of the lowest habitable floor (including
basement) of all new or substantially improved structures, and whether or not
the structure contains a basement.
Title 7, Chapter 10 Page 14 of 39 Revised 2-2021
(b) For all new or substantially improved floodproofed structures:
(1) Verify and record the actual elevation (in relation to mean sea level), and
(2) Maintain the floodproofing certifications required in Section 7-10-5 (B)
3.
(3) Maintain for public inspection all records pertaining to the provisions of
this chapter.
4. Alteration of Watercourses:
(a) Notify adjacent communities and the Idaho Water Resource Board prior to
any alteration or relocation of a water course, and submit evidence of such
notification to the Federal Insurance Administration.
(b) Require that maintenance is provided within the altered or relocated portion
of said water course so that the flood carrying capacity is not diminished.
(c). Interpretation of FIRM Boundaries: Make interpretations where needed, as
to exact location of the boundaries of the areas of special flood hazards (for
example, where there appears to be a conflict between a mapped boundary and
the actual field conditions). The person contesting the location of the boundary
shall be given a reasonable opportunity to appeal the interpretation. Such
appeals shall be granted consistent with the appeals procedure as provided in
Section 7-10-4(D)4 of this chapter and the standards of Section 1910.6 of the
rules and regulations of the National Flood Insurance Program (24 CFR 1909,
etc.)
(d). When floodproofing is utilized for a particular structure, obtain and
maintain certifications from a registered professional engineer or architect in
accordance with the provisions of 7-10-3(b) and 7-10-5 (B)2.
(e). When Base Flood Elevation (BFE) data is provided but no floodway data
has been provided in accordance with the provisions of 7-10-3(B) require that
no new construction, substantial improvements, or other development
(including fill) shall be permitted within Zones AE on the community's FIRM,
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 the community. (This is a Hydraulic &
Hydrology Analysis)
(f). Make on-site inspections of work in progress. As the work pursuant to a
floodplain development permit progresses, the Floodplain Administrator shall
make as many inspections of the work as may be necessary to ensure that the
Title 7, Chapter 10 Page 15 of 39 Revised 2-2021
work is being done according to the provisions of the local ordinance and the
terms of the permit. In exercising this power, the Floodplain Administrator has
a right, upon presentation of proper credentials, to enter on any premises within
the jurisdiction of the community at any reasonable hour for the purposes of
inspection or other enforcement action.
(g). Issue stop-work orders as required. Whenever a building or part thereof is
being constructed, reconstructed, altered, or repaired in violation of this
ordinance, the Floodplain Administrator may order the work to be immediately
stopped. The stop-work order shall be in writing and directed to the person
doing or in charge of the work. The stop-work order shall state the specific
work to be stopped, the specific reason(s) for the stoppage, and the condition(s)
under which the work may be resumed. Violation of a stop-work order
constitutes a misdemeanor.
(h). Revoke floodplain development permits as required. The Floodplain
Administrator may revoke and require the return of the floodplain development
permit by notifying the permit holder in writing stating the reason(s) for the
revocation. Permits shall be revoked for any substantial departure from the
approved application, plans, and specifications; for refusal or failure to comply
with the requirements of State or local laws; or for false statements or
misrepresentations made in securing the permit. Any floodplain development
permit mistakenly issued in violation of an applicable State or local law may
also be revoked.
(i). Make periodic inspections throughout the Special Flood Hazard Areas
within the jurisdiction of the community. The Floodplain Administrator and
each member of his or her inspections department shall have a right, upon
presentation of proper credentials, to enter on any premises within the territorial
jurisdiction of the department at any reasonable hour for the purposes of
inspection or other enforcement action.
(g. Review, provide input, and make recommendations for variance requests.
(j). Maintain a current map repository to include, but not limited to, the FIS
Report, FIRM and other official flood maps, and studies adopted in accordance
with the provisions of Article III, Section B of this ordinance, including any
revisions thereto including Letters of Map Change, issued by FEMA. Notify the
NFIP State Coordinator and FEMA of your community’s mapping needs.
(k). Coordinate revisions to FIS reports and FIRMs, including Letters of Map
Revision Based on Fill (LOMR-Fs) and Letters of Map Revision (LOMRs).
(l). A community's base flood elevations may increase or decrease resulting
from physical changes affecting flooding conditions. As soon as practicable, but
not later than six months after the date such information becomes available, a
community shall notify the Federal Insurance Administrator (FIA) of the
changes by submitting technical or scientific data in accordance with this part.
Title 7, Chapter 10 Page 16 of 39 Revised 2-2021
Such a submission is necessary so that upon confirmation of those physical
changes affecting flooding conditions, risk premium rates and floodplain
management requirements will be based upon current data.
(m). Upon occurrence, notify the Federal Insurance Administrator (FIA) in
writing whenever the boundaries of the community have been modified by
annexation or the community has otherwise assumed or no longer has authority
to adopt and enforce floodplain management regulations for a particular area. In
order that all FHBM's and FIRM's accurately represent the community's
boundaries, include within such notification a copy of a map of the community
suitable for reproduction, clearly delineating the new corporate limits or new
area for which the community has assumed or relinquished flood plain
management regulatory authority
(D) Floodplain Development Application, Permit, and Certification Requirements
1. Application Requirements: Application for a Floodplain Development Permit
shall be made to the Floodplain Administrator prior to any development activities
located within Special Flood Hazard Areas. The following items shall be presented
to the Floodplain Administrator to apply for a floodplain development permit:
(a). A plot plan drawn to scale which shall include, but shall not be limited to,
the following specific details of the proposed floodplain development:
1. the nature, location, dimensions, and elevations of the area of
development/disturbance; existing and proposed structures, utility systems,
grading/pavement areas, fill materials, storage areas, drainage facilities,
and other development;
2. the boundary of the Special Flood Hazard Area as delineated on the
FIRM or other flood map as determined in 7-10-3(B), or a statement that
the entire lot is within the Special Flood Hazard Area;
3. the flood zone(s) designation of the proposed development area as
determined on the FIRM or other flood map as determined in Article III,
Section B;
4. the boundary of the floodway(s) as determined in Article III, Section B;
5. the Base Flood Elevation (BFE) where provided as set forth in7-10-3(B)
6. the old and new location of any watercourse that will be altered or
relocated as a result of proposed development; and
(b). Proposed elevation, and method thereof, of all development within a
Special Flood Hazard Area including but not limited to:
Title 7, Chapter 10 Page 17 of 39 Revised 2-2021
1. Elevation in relation to mean sea level of the proposed lowest floor
(including basement) of all structures;
2. Elevation in relation to mean sea level to which any non-residential
structure in Zone A, AE, AH, or AO will be floodproofed; and
3. Elevation in relation to mean sea level to which any proposed
utility equipment and machinery will be elevated or floodproofed.
(c). If floodproofing, a Floodproofing Certificate (FEMA Form 086-0-33) with
supporting data, an operational plan, and an inspection and maintenance plan
that include, but are not limited to, installation, exercise, and maintenance of
flood proofing measures will be required prior to Certificate of
Occupancy/Completion.
(d). A Foundation Plan, drawn to scale, which shall include details of the
proposed foundation system to ensure all provisions of this ordinance are met.
These details include but are not limited to:
1. The proposed method of elevation, if applicable (i.e., fill, solid
foundation perimeter wall, solid backfilled foundation, open foundation, or
on columns/posts/piers/piles/shear walls); and
2. Openings to facilitate automatic equalization of hydrostatic flood forces
on walls in accordance with Article V, Section A.8.b. when solid
foundation perimeter walls are used in Zones A, AE, AH, and AO.
(e). Usage details of any enclosed areas below the lowest floor.
(f). Plans and/or details for the protection of public utilities and facilities such as
sewer, gas, electrical, and water systems to be located and constructed to
minimize flood damage.
(g). Certification that all other Local, State, and Federal permits required prior
to floodplain development permit issuance have been received.
(h). Documentation for placement of recreational vehicles and/or temporary
structures, when applicable, to ensure that the provisions of 7-10-5 (B) 5&6. of
this ordinance are met.
(i). A description of proposed watercourse alteration or relocation, when
applicable, including an engineering report on the effects of the proposed
project on the flood-carrying capacity of the watercourse and the effects to
properties located both upstream and downstream; and
1. A map (if not shown on plot plan) showing the location of the proposed
watercourse alteration or relocation.
2. Permit Requirements: The Floodplain Development Permit shall include, but not
be limited to:
(a). A complete description of all the development to be permitted under the
Title 7, Chapter 10 Page 18 of 39 Revised 2-2021
floodplain development permit (i.e. house, garage, pool, septic, bulkhead,
cabana, pole barn, chicken coop, pier, bridge, mining, dredging, filling, rip-rap,
docks, grading, paving, excavation or drilling operations, or storage of
equipment or materials, etcetera).
(b). The Special Flood Hazard Area determination for the proposed
development in accordance with available data specified in 7-10-3(B).
(c). The Flood Protection Elevation required for the lowest floor and all
attendant utilities.
(d). The Flood Protection Elevation required for the protection of all utility
equipment and machinery.
(e). All certification submittal requirements with timelines.
(f). A statement that no fill material or other development shall encroach into
the floodway of any watercourse, as applicable.
(g). The flood openings requirements, if in Zones A, AE, AH, or AO.
(h). All floodplain development permits shall be conditional upon the start of
construction of work within 180 days. A floodplain development permit shall
expire 180 days after issuance unless the permitted activity has commenced as
per the Start of Construction definition.
(i). Fully enclosed areas below the lowest floor are usable solely for parking of
vehicles, building access, or storage.
(j). All materials below BFE/FPE must be flood resistant materials.
3. Certification Requirements:
(a). Elevation Certificates
1. A Construction Drawings Elevation Certificate (FEMA Form 86-0-33)
is required prior to the actual start of any new construction. It shall be the
duty of the permit holder to submit to the Floodplain Administrator a
certification of the elevation of the lowest floor, in relation to mean sea
level. The Floodplain Administrator shall review the certificate data
submitted. Deficiencies detected by such review shall be corrected by the
permit holder prior to the beginning of construction. Failure to submit the
certification or failure to make required corrections shall be cause to deny
a floodplain development permit.
2. A Building Under Construction Elevation Certificate (FEMA Form 86-
0-33) is required after the lowest floor is established. Within seven (7)
calendar days of establishment of the lowest floor elevation, it shall be the
duty of the permit holder to submit to the Floodplain Administrator a
certification of the elevation of the lowest floor, in relation to mean sea
level. Any work done within the seven (7) day calendar period and prior
Title 7, Chapter 10 Page 19 of 39 Revised 2-2021
to submission of the certification shall be at the permit holder’s risk. The
Floodplain Administrator shall review the certificate data submitted.
Deficiencies detected by such review shall be corrected by the permit
holder immediately and prior to further work being permitted to proceed.
Failure to submit the certification or failure to make required corrections
shall be cause to issue a stop-work order for the project.
3. A final as-built Finished Construction Elevation Certificate (FEMA
Form 86-0-33) is required after construction is completed and prior to
Certificate of Compliance/Occupancy issuance. It shall be the duty of the
permit holder to submit to the Floodplain Administrator a certification of
final as-built construction of the elevation of the lowest floor and all
attendant utilities. The Floodplain Administrator shall review the
certificate data submitted. Deficiencies detected by such review shall be
corrected by the permit holder immediately and prior to Certificate of
Compliance/Occupancy issuance. In some instances, another certification
may be required to certify corrected as-built construction. Failure to
submit the certification or failure to make required corrections shall be
cause to withhold the issuance of a Certificate of Compliance/Occupancy.
(b). Floodproofing Certificate. If non-residential floodproofing is used to meet
the Flood Protection Elevation requirements, design plans, with supporting data,
an operational plan, and an inspection and maintenance plan are required prior
to the actual start of any new construction. It shall be the duty of the permit
holder to submit to the Floodplain Administrator a certification of the
floodproofed design elevation of the lowest floor and all attendant utilities, in
relation to mean sea level. Floodproofing certification shall be prepared by or
under the direct supervision of a professional engineer or architect and certified
by same. The Floodplain Administrator shall review the certificate data, the
operational plan, and the inspection and maintenance plan. Deficiencies
detected by such review shall be corrected by the applicant prior to permit
approval. Failure to submit the certification or failure to make required
corrections shall be cause to deny a Floodplain Development Permit. Prior to
request for a Certificate of Compliance/Occupancy a Floodproofing Certificate
(FEMA Form 086-0-34) shall be provided to the Floodplain Administrator for
review and approval.
(c). If a manufactured home is placed within Zone A, AE, AH, or AO and the
elevation of the chassis is more than 36 inches in height above grade, an
engineered foundation certification is required in accordance with the provisions
of 7-10-5 (B)3(b).
(d). If a watercourse is to be altered or relocated, the following shall all be
Title 7, Chapter 10 Page 20 of 39 Revised 2-2021
submitted by the permit applicant prior to issuance of a floodplain development
permit:
1. a description of the extent of watercourse alteration or relocation; and
2. a professional engineer’s certified report on the effects of the proposed
project on the flood-carrying capacity of the watercourse and the effects to
properties located both upstream and downstream; and
3. a map showing the location of the proposed watercourse alteration or
relocation; and
4. an Idaho Stream Channel Alteration Permit approval shall be provided
by the applicant to the Floodplain Administrator.
(e). Certification Exemptions. The following structures are exempt from the
elevation/floodproofing certification requirements specified in items a. and b. of
this subsection:
1. Recreational Vehicles meeting requirements of 7-10-5 (B)5(a);
2. Temporary Structures meeting requirements of 7-10-5 (B)6; and
3. Accessory Structures less than 200 square feet meeting requirements of
7-10-5 (B)7.
(E) Determinations for Existing Buildings and Structures. For applications for building
permits to improve buildings and structures, including alterations, movement,
enlargement, replacement, repair, change of occupancy, additions, rehabilitations,
renovations, improvements, repairs of damage, and any other improvement of or work
on such buildings and structures, the Floodplain Administrator, in coordination with the
Building Official, shall:
1. Estimate the market value, or require the applicant to obtain an appraisal of the
market value prepared by a qualified independent appraiser, of the building or
structure before the start of construction of the proposed work. In the case of repair,
the market value of the building or structure shall be the market value before the
damage occurred and before any repairs are made;
2. Compare the cost to perform the improvement, the cost to repair a damaged
building to its pre-damaged condition, or the combined costs of improvements and
repairs, if applicable, to the market value of the building or structure;
3. Determine and document whether the proposed work constitutes substantial
improvement or repair of substantial damage; and
4. Notify the applicant if it is determined that the work constitutes substantial
improvement or repair of substantial damage and that compliance with the flood
resistant construction requirements of the adopted Idaho Building Code and this
ordinance is required.
Title 7, Chapter 10 Page 21 of 39 Revised 2-2021
(F). Corrective Procedures
1. Violations to be Corrected: When the Floodplain Administrator finds violations
of applicable State and local laws, it shall be his or her duty to notify the owner or
occupant of the building of the violation. The owner or occupant shall immediately
remedy each of the violations of law cited in such notification.
2. Actions in Event of Failure to Take Corrective Action: If the owner of a building
or property shall fail to take prompt corrective action, the Floodplain Administrator
shall give the owner written notice, by certified or registered mail to the owner’s
last known address or by personal service, stating:
(a). that the building or property is in violation of the floodplain management
regulations;
(b). that a hearing will be held before the Floodplain Administrator at a
designated place and time, not later than ten (10) days after the date of the
notice, at which time the owner shall be entitled to be heard in person or by
counsel and to present arguments and evidence pertaining to the matter; and
(c). that following the hearing, the Floodplain Administrator may issue an order
to alter, vacate, or demolish the building; or to remove fill as applicable.
3. Order to Take Corrective Action. If, upon a hearing held pursuant to the notice
prescribed above, the Floodplain Administrator shall find that the building or
development is in violation of the Flood Damage Prevention Ordinance, he or she
shall issue an order in writing to the owner, requiring the owner to remedy the
violation within a specified time period, not less than sixty (60) calendar days, nor
more than 180 calendar days. Where the Floodplain Administrator finds that there
is imminent danger to life or other property, he or she may order that corrective
action be taken in such lesser period as may be feasible.
(a). Appeal: Any owner who has received an order to take corrective action may
appeal the order to the local elected governing body by giving notice of appeal
in writing to the Floodplain Administrator and the clerk within ten (10) days
following issuance of the final order. In the absence of an appeal, the order of
the Floodplain Administrator shall be final. The local governing body shall hear
an appeal within a reasonable time and may affirm, modify and affirm, or
revoke the order.
(b). Failure to Comply with Order: If the owner of a building or property fails to
comply with an order to take corrective action for which no appeal has been
made or fails to comply with an order of the governing body following an
appeal, the owner shall be guilty of a misdemeanor and shall be punished at the
discretion of the court.
4. Variance Procedure:
Title 7, Chapter 10 Page 22 of 39 Revised 2-2021
(a). Appeal Board:
(1) The Board of Adjustment or the City Council acting as the
Board of Adjustment, as established by the City of Ammon, shall
hear and decide appeals and requests for variances from the
requirements of this chapter.
(2) The Board of Adjustment, or the City Council acting as the
Board of Adjustment, shall hear and decide appeals when it is
alleged there is an error in any requirement, decision, or
determination made by the Enforcement Officer in the enforcement
or administration of this chapter.
(3) Those aggrieved by the decision of the Board of Adjustment, or
the City Council acting as the Board of Adjustment, or any
taxpayer, may appeal such decision to the Seventh Judicial District
Court, as provided by Idaho statutes.
(4) In passing upon such applications, the Board of Adjustment, or
the City Council acting as the Board of Adjustment, shall consider
all technical evaluations, all relevant factors, standards specified in
other sections of this chapter, and:
(a) The danger that materials may be swept onto other lands to
the injury of others;
(b) The danger to life and property due to flooding or erosion
damage;
(c) The susceptibility of the proposed facility and its contents to
flood damage and the effect of such damage on the individual
owner;
(d) The importance of the services provided by the proposed
facility to the community;
(e) The necessity to the facility of a waterfront location, where
applicable;
(f) The availability of alternative locations for the proposed use
which are not subject to flooding or erosion damage;
(g) The compatibility of the proposed use with existing and
anticipated development;
(h) The relationship of the proposed use to the comprehensive
plan and floodplain management program for that area;
(i) The safety of access to the property in times of flood for
ordinary and emergency vehicles;
(j) The expected heights, velocity, duration, rate of rise, and
sediment transport of the flood waters and the effects of wave
Title 7, Chapter 10 Page 23 of 39 Revised 2-2021
action, if applicable, expected at the site; and
(k) The costs of providing governmental services during and
after flood conditions, including maintenance and repair of
public utilities and facilities such as sewer, gas, electrical, and
water systems, and streets and bridges.
(5) Upon consideration of the factors of Section 7-10-4 (D) 1(d) and
the
purposes of this chapter, the Board of Adjustment, or the City
Council
acting as the Board of Adjustment, may attach such conditions to the
granting of variances as it deems necessary to further the purposes of
this chapter.
(6) The City Engineer shall maintain the records of all appeal actions
and report any variances to the Federal Insurance Administration
upon
request.
(b). Conditions for Variance:
(1) Generally, the only condition under which a variance from the
elevation
standard may be issued is for new construction and substantial
improvements to be erected on a lot of one-half (½) acre or less in size
contiguous to and surrounded by lots with existing structures
constructed below the base flood level, providing items (i-xi) in
Section 7-10-4 (D) 1(d) have been fully considered. As the lot size
increases the technical justification required for issuing the variance
increases.
(2) Variances may be issued for the reconstruction, rehabilitation, or
restoration of structures listed on the National Register of Historic
Places or the State Inventory of Historic Places, without regard to the
procedures set forth in this section.
(3) Variances shall not be issued within a designated floodway if any
increase in flood levels during the base flood discharge would result.
(4) Variances shall only be issued upon a determination that the
variance is the minimum necessary, considering the flood hazard, to
afford relief.
(5) functionally dependent facilities, if determined to meet the
definition as stated in Article II of this ordinance, provided
provisions of 7-10-4 (E)2, have been satisfied, and such facilities are
protected by methods that minimize flood damages during the base
flood and create no additional threats to public safety; or
Title 7, Chapter 10 Page 24 of 39 Revised 2-2021
(6) any other type of development, provided it meets the
requirements of this Section.
(7) Variances shall only be issued upon:
(a) A showing of good and sufficient cause;
(b) A determination that failure to grant the variance would result
in
exceptional hardship to the applicant;
(c) A determination that the granting of a variance will not result
in
increased flood heights, additional threats to public safety,
extraordinary public expense, create nuisances, cause fraud on or
victimization of the public, or conflict with existing local laws or
ordinances.
(8) Variances as interpreted in the National Flood Insurance Program
are based on the general zoning law principle that they pertain to a
physical piece of property; they are not personal in nature and do not
pertain to the structure, its inhabitants, economic or financial
circumstances. They primarily address small lots in densely
populated residential neighborhoods. As such, variances from the
flood elevations should be quite rare.
(7) Variances may be issued for nonresidential buildings in very
limited
circumstances to allow a lesser degree of floodproofing than
watertight or dry-floodproofing, where it can be determined that
such action will have low damage potential, complies with all other
variance criteria except Section 7-10-4 (D) 2(a), and otherwise
complies with Sections 7-10-5 (A) 1 and 7-10-5 (A) 2 of the
GENERAL STANDARDS.
(8) Any applicant to whom a variance is granted shall be given
written notice that the structure will be permitted to be built with a
lowest floor elevation below the base flood elevation and that the
cost of flood insurance will be commensurate with the increased risk
resulting from the reduced lowest floor elevation.
7-10-5: PROVISIONS FOR FLOOD HAZARD PROTECTION:
(A) General Standards: In all areas of special flood hazards, the following standards
are
Title 7, Chapter 10 Page 25 of 39 Revised 2-2021
required:
1. Anchoring:
(a) All new construction and substantial improvements shall be anchored to
prevent flotation, collapse, or lateral movement of the structure.
(b) All manufactured homes must likewise 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 or frame ties to ground anchors.
(Reference FEMA’s “Manufactured Home Installation in Flood Hazard
Areas” guidebook for additional techniques.)
2. Construction Materials and Methods:
(a) All new construction and substantial improvements shall be constructed
with materials and utility equipment resistant to flood damage in accordance
with the Technical Bulletin 2, Flood Damage-Resistant Materials
Requirements, and available from the Federal Emergency Management
Agency.
(b) All new construction and substantial improvements shall be constructed
using methods and practices that minimize flood damage.
(c) Electrical, heating, ventilation, plumbing, and air-conditioning equipment
and other service facilities shall be designed and/or otherwise elevated or
located so as to prevent water from entering or accumulating within the
components during conditions of flooding to the Flood Protection Elevation.
These include, but are not limited to, HVAC equipment, water softener units,
bath/kitchen fixtures, ductwork, electric/gas meter panels/boxes, utility/cable
boxes, hot water heaters, and electric outlets/switches.
3. Utilities:
(a) All new and replacement water supply systems shall be designed to
minimize or eliminate infiltration of flood waters into the system;
(b) New and replacement sanitary sewage systems shall be designed to
minimize or eliminate infiltration of flood waters into the systems and
discharge from the systems into flood waters; and
(c) On-site waste disposal systems shall be located to avoid impairment to
Title 7, Chapter 10 Page 26 of 39 Revised 2-2021
them or contamination from them during flooding.
4. Subdivision Proposals:
(a) All subdivision proposals shall be required to mitigate and remove from
the flood plain prior to any building permits being issued on lots within the
boundaries of the floodplain as they now exist.
(b) All subdivision proposals shall have public utilities and facilities such as
sewer, gas, electrical, and water systems located and constructed to minimize
flood damage;
(c) All subdivision proposals shall have adequate drainage provided to reduce
exposure to flood damage; and
(d) Base flood elevation data shall be provided for subdivision proposals and
other proposed development which contain at least fifty (50) lots or five (5)
acres, whichever is less.
(e) All subdivision proposals and other development proposals shall have
received all necessary permits from those governmental agencies for which
approval is required by Federal or State law, including Section 404 of the
Federal Water Pollution Control Act Amendments of 1972, 33 USC 1334
5. Review of Building Permits: Where elevation data is not available either
through
the Flood Insurance Study or from another authoritative source (Section
7-10-4(C)2), 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.
6.Nothing in this ordinance shall prevent the repair, reconstruction, or
replacement of a building or structure existing on the effective date of this
ordinance and located totally or partially within the floodway, or stream setback,
provided there is no additional encroachment below the Flood Protection
Elevation in the floodway, or stream setback, and provided that such repair,
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reconstruction, or replacement meets all of the other requirements of this
ordinance.
(B) Specific Standards: In all areas of special flood hazards where base flood elevation
data
has been provided as set forth in Section 7-10-3(B), Basis for Establishing the Area of
Special Flood Hazard or Section 7-10-4(C)2, use of Other Base Flood Data, the
following provisions are required:
1. Residential Construction:
(a) New construction and substantial improvement of any residential
structure shall have the lowest floor, including basement, elevated to or
above base flood elevation, or comply with flood proof basement
requirements as set forth in Section 7-10-6 of this chapter.
(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 either be certified by
a registered professional engineer or architect or must meet or exceed the
following minimum criteria:
(1) A minimum of two openings having a total net area of not less than
one square inch for every square foot of enclosed are subject to flooding
shall be provided;
(2) The bottom of all openings shall be no higher than one foot above
grade;
(3) Openings may be equipped with screens, louvers, or other
coverings or devices provided that they permit the automatic entry
and exit of floodwaters.
(4) If a building has more than one enclosed area, each enclosed area
must have flood openings to allow floodwaters to automatically enter and
exit;
(5) Enclosures made of flexible skirting are not considered enclosures for
regulatory purposes, and, therefore, do not require flood openings.
Masonry or flood resistant wood underpinning, regardless of structural
status, is considered an enclosure and requires flood openings as outlined
above.
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2. Nonresidential Construction: New construction and substantial improvement
of
any commercial, industrial, or other nonresidential structure shall either have the
lowest floor, including basement, elevated to the level of the base flood
elevation;
or, together with attendant utility and sanitary facilities, shall:
(a) Be floodproofed so that below the base flood level the structure is
watertight with walls substantially impermeable to the passage of water;
(b) Have structural components capable of resisting hydrostatic and
hydrodynamic loads and effects of buoyancy;
(c) 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, specifications,
and plans. Such certifications shall be provided to the officials as set forth
in Section 7-10-4(C)3(b); and
(d) Nonresidential structures that are elevated, not floodproofed, must meet
the same standards for space below the lowest floor as described in Section
7-10-5 (B) 1(2).
(e) Manufactured Homes: All manufactured homes to be placed or
substantially improved within Zones A1-30, AH, and AE shall be elevated on
a permanent foundation such that the lowest floor of the manufactured home
is at or above the base flood elevation and be securely anchored to an
adequately anchored foundation system in accordance with the provisions of
Section 7-10-5 (A) 1(b).
(f) New solid waste disposal facilities and sites, hazardous waste
management facilities, salvage yards, and chemical storage facilities shall not
be permitted, except by variance as specified in Article IV, Section E.9. A
structure or tank for chemical or fuel storage incidental to an allowed use or
to the operation of a water treatment plant or wastewater treatment facility
may be located in a Special Flood Hazard Area only if the structure or tank is
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either elevated or floodproofed to at least the Flood Protection Elevation and
certified in accordance with the provisions of 7-10-4 (C) 3.
3. Basements:
(a) Be designed and built so that any basement area, together with attendant
utilities and sanitary facilities below the floodproofed design level, is
watertight with walls that are impermeable to the passage of water without
human intervention. Basement walls shall be built with the capacity to resist
hydrostatic and hydrodynamic loads and the effects of buoyancy resulting
from flooding to the floodproofed design level, and shall be designed so that
minimal damage will occur from floods that exceed that level. The
floodproofed design level shall be an elevation one foot above the level of
the base flood where the difference between the base flood and the 500-year
flood is three feet or less and two feet above the level of the base flood where
the difference is greater than three feet.
(b) Have the top of the floor of any basement area no lower than five feet
below the elevation of the base flood;
(c) Have the area surrounding the structure on all sides filled to or above the
elevation of the base flood. Fill must be compacted with slopes protected by
vegetative cover;
(d) Have a registered professional engineer or architect develop or review the
building's structural design, specifications, and plans, including consideration
of the depth, velocity, and duration of flooding and type and permeability of
soils at the building site, and certify that the basement design and methods of
construction proposed are in accordance with accepted standards of practice
for meeting the provisions of this paragraph;
(e) Be inspected by the building inspector or other authorized representative
of the community to verify that the structure is built according to its design
and those provisions of this section which are verifiable.
4. Additions/Improvements:
a. Additions and/or improvements to pre-FIRM structures when the addition
and/or improvements in combination with any interior modifications to the
existing structure are
1. not a substantial improvement, the addition and/or improvements must
be designed to minimize flood damages and must not be any more non-
conforming than the existing structure; or
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2. a substantial improvement, both the existing structure and the addition
and/or improvements must comply with the standards for new
construction.
b. Additions to non-compliant post-FIRM structures that are a substantial
improvement with no modifications to the existing structure other than a
standard door in the common wall shall require only the addition to comply
with the standards for new construction.
c. Additions and/or improvements to non-compliant post-FIRM structures
when the addition and/or improvements in combination with any interior
modifications to the existing structure are
1. not a substantial improvement, the addition and/or improvements only
must comply with the standards for new construction; or
2. a substantial improvement, both the existing structure and the addition
and/or improvements must comply with the standards for new
construction.
d. Any combination of repair, reconstruction, rehabilitation, addition, or
improvement of a building or structure taking place during a 10-year period,
the cumulative cost of which equals or exceeds 50 percent (50%) of the
market value of the structure before the improvement or repair is started,
must comply with the standards for new construction. For each building or
structure, the 10-year period begins on the date of the first improvement or
repair of that building or structure subsequent to the effective date of this
ordinance. If the structure has sustained substantial damage, any repairs are
considered substantial improvement regardless of the actual repair work
performed. The requirement does not, however, include either:
1. any project for improvement of a building required to correct existing
health, sanitary, or safety code violations identified by the building
official and that are the minimum necessary to assume safe living
conditions; or
2. any alteration of a historic structure provided that the alteration will
not preclude the structure’s continued designation as a historic structure.
5. Recreational Vehicles. Recreational vehicles shall be either:
a. Temporary Placement
1.be on site for fewer than 180 consecutive days and 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 has no permanently attached additions); or
b. Permanent Placement.
1. Recreational vehicles that do not meet the limitations of
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Temporary Placement shall meet all the requirements for new
construction, as set forth in 7-10-5 (A).
6. Temporary Non-Residential Structures:
Prior to the issuance of a floodplain development permit for a temporary
structure, the applicant must submit to the Floodplain Administrator a plan for the
removal of such structure(s) in the event of a flash flood or other type of flood
warning notification. The following information shall be submitted in writing to
the Floodplain Administrator for review and written approval:
a. a specified time period for which the temporary use will be permitted.
Time specified may not exceed six (6) months, renewable up to one (1) year;
b. the name, address, and phone number of the individual responsible for the
removal of the temporary structure;
c. the time frame prior to the event at which a structure will be removed (i.e.,
immediately upon flood warning notification);
d. a copy of the contract or other suitable instrument with the entity
responsible for physical removal of the structure; and
e. designation, accompanied by documentation, of a location outside the
Special Flood Hazard Area, to which the temporary structure will be moved.
f. Temporary structures in the floodway must provide a Hydraulic and
Hydrology Analysis along with a No-Rise Certification.
7. Accessory and Agricultural Structures (Appurtenant structures):
When accessory structures (sheds, detached garages, etc.) used solely for parking,
and storage are to be placed within a Special Flood Hazard Area, elevation or
floodproofing certifications are required for all accessory structures in accordance
with 7-10-4 (D) 3, and the following criteria shall be met:
a. Accessory structures shall not be used for human habitation (including
working, sleeping, living, cooking, or restroom areas);
b. Accessory structures shall not be temperature-controlled;
c. Accessory structures shall be designed to have low flood damage
potential;
d. Accessory structures shall be constructed and placed on the building site
so as to offer the minimum resistance to the flow of floodwaters;
e. Accessory structures shall be firmly anchored in accordance with the
provisions of 7-10-5 (A)1;
f. All utility equipment and machinery, such as electrical, shall be installed
in accordance with the provisions of 7-10-5 (A)2(c); and
g. Flood openings to facilitate automatic equalization of hydrostatic flood
Title 7, Chapter 10 Page 32 of 39 Revised 2-2021
forces shall be provided below Flood Protection Elevation in conformance
with the provisions of 7-10-5(B)1(b).
h. Accessory structures not used solely for parking, access, and storage must
be elevated per 7-10-5 (B)1 and 7-10-5 (B)2.
An accessory structure with a footprint less than 200 square feet and is a
minimal investment of $7,500 and satisfies the criteria outlined in a - g above
is not required to provide the elevation certificate per 7-10-5 (B)2.
8. Tanks:
When gas and liquid storage tanks are to be placed within a Special Flood Hazard
Area, the following criteria shall be met:
a. Underground tanks in flood hazard areas shall be anchored to prevent
flotation, collapse, or lateral movement resulting from hydrodynamic and
hydrostatic loads during conditions of the base flood, including the effects of
buoyancy (assuming the tank is empty);
b. Elevated above-ground tanks, in flood hazard areas shall be attached to
and elevated to or above the design flood elevation on a supporting structure
that is designed to prevent flotation, collapse, or lateral movement during
conditions of the base flood. Tank-supporting structures shall meet the
foundation requirements of the applicable flood hazard area;
c. Not elevated above-ground tanks may be permitted in flood hazard areas
provided the tanks are anchored or otherwise designed and constructed to
prevent flotation, collapse or lateral movement resulting from hydrodynamic
and hydrostatic loads during conditions of the design flood, including the
effects of buoyancy assuming the tank is empty and the effects of flood-
borne debris.
d. Tank inlets, fill openings, outlets and vents shall be:
1. at or above the flood protection elevation or fitted with covers
designed to prevent the inflow of floodwater or outflow of the contents
of the tanks during conditions of the base flood; and
2. anchored to prevent lateral movement resulting from
hydrodynamic and hydrostatic loads, including the effects of buoyancy,
during conditions of the base flood.
9. Construction of Below-Grade Crawlspace:
a. The interior grade of a crawlspace must not be below the BFE and must
not be more than two (2) feet below the exterior lowest adjacent grade
(LAG).
b. The height of the below-grade crawlspace, measured from the interior
grade of the crawlspace to the top of the crawlspace foundation wall, must
not exceed four (4) feet at any point.
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c. There must be an adequate drainage system that removes floodwaters from
the interior area of the crawlspace. The enclosed area should be drained
within a reasonable time after a flood event.
d. The velocity of floodwaters at the site should not exceed five (5) feet per
second for any crawlspace.
10. Critical Facilities:
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 (3') 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.
(C) Floodways: Located within areas of special flood hazard establishments in Section
7-10-3 (B) are areas designated as floodways. Since the floodway is an extremely
hazardous area due to the velocity of flood waters which carry debris, potential
projectiles, and erosion potential, the following provisions apply:
1. Prohibit encroachments, including fill, new construction, substantial
improvement,
and other development unless certification by a registered professional engineer
or architect is provided demonstrating that encroachments shall not result in any
increase in flood levels during the occurrence of the base flood discharge.
2. If Section 7-10-5(C)-1 is satisfied, all new construction and substantial
improvements shall comply with all applicable flood hazard reduction
provisions of Section 7-10-5, PROVISIONS FOR FLOOD HAZARD
REDUCTION.
3. Prohibit the placement of any mobile homes, except in an existing mobile
home park or existing mobile home subdivision.
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(D) Standards for Floodplains without Established Base Flood Elevations
Within the Special Flood Hazard Areas designated as Zone A (also known as
Unnumbered A Zones) and established in 7-10-3 (B), where no Base Flood Elevation
(BFE) data has been provided by FEMA, the following provisions, in addition to the
provisions of 7-10-5 (A), shall apply:
The BFE used in determining the Flood Protection Elevation (FPE) shall be
determined based on the following criteria:
1. When Base Flood Elevation (BFE) data is available from other sources, all
new construction and substantial improvements within such areas shall also
comply with all applicable provisions of this ordinance and shall be elevated or
floodproofed in accordance with standards in 7-10-5 (A) and 7-10-5 (B).
2. When floodway data is available from a Federal, State, or other source, all
new construction and substantial improvements within floodway areas shall also
comply with the requirements of 7-10-5 (B).
3. Require that all new subdivision proposals and other proposed
developments (including proposals for manufactured home parks and
subdivisions) greater than 50 lots or 5 acres, whichever is the lesser, include
within such proposals base flood elevation data. Such Base Flood Elevation
(BFE) data shall be adopted by reference in accordance with Article III, Section
B and utilized in implementing this ordinance. See FEMA 480 and/or FEMA
265 for further information
4. When Base Flood Elevation (BFE) data is not available from a Federal, State,
or other source as outlined above, the lowest floor shall be elevated or
floodproofed (non-residential) to two feet (2.0 ft.) above the Highest Adjacent
Grade (HAG) at the building site or to the Flood Protection Elevation (FPE)
whichever is higher, as defined in 7-10-2. All other applicable provisions of
Article V, Section B shall also apply.
(E) Standards for Shallow Flooding Areas (AO Zones):
1. Shallow flooding areas appear in FIRM’s as AO zones with depth
designations. The base flood depths in these zones range from one (1) to three
(3) feet where a clearly defined channel does not exist, or where the path of
flooding is unpredictable and where velocity flow may be evident. Such
flooding is usually characterized as sheet flow. In these areas, the following
provisions apply:
(a) New construction and substantial improvements of residential
structures within AO zones shall have the lowest floor (including
basement) elevated above the adjacent grade of the building site, to or
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above the depth number specified on the FIRM (at least two (2) feet if no
depth number is specified).
(b) New construction and substantial improvements of nonresidential
structures within AP zones shall either:
(1) The lowest floor (including basement) elevated above the
adjacent
grade of the building site, to or above the depth number specified
on the FIRM (at least two (2) feet if no depth number is specified);
or
(2) Together with attendant utility and sanitary facilities, be
completely
floodproofed to or above that 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. If this method is used, compliance shall be
certified by a registered professional engineer or architect as in
Section 7-10-5 (B) 2(c).
(c) Require adequate drainage paths around structures on slopes to guide
floodwaters around and away from proposed structures.
(d) Shall have flood openings to facilitate automatic equalization of
hydrostatic flood forces shall be provided below Flood Protection
Elevation
7-10-6: REPEALED
7-10-7: ACCESSORY STRUCTURES:
(A) Accessory structures to a main structure shall be defined as those structures which
are
utilized in connection with a main structure, but in and of the accessory structure itself
does not constitute a main purpose of function of the improvement. Such accessory
buildings shall include, but not by way of limitation, storage sheds, tool sheds, garden
buildings, greenhouses, detached garages, kennels, and barns.
(B) No such accessory structure shall at any time be used for human habitation.
Title 7, Chapter 10 Page 36 of 39 Revised 2-2021
(C) All such accessory structures shall be designed to have low flood damage
potential.
(D) All such accessory structures shall be constructed and place on the building site so
as to offer the minimum resistance to the flow of flood waters.
(E) All such accessory structures shall be firmly anchored to prevent flotation which
may
result in damage to other structures.
(F) All service facilities to any such accessory structure such as electrical and heating
equipment shall be elevated or floodproofed.
(G) When an accessory structure represents a minimal investment, the elevation or dry
floodproofing standards need not be met. However, all other requirements applicable
to
structures will be applicable. A minimal investment shall be determined by the
applicable
building authority, or by the appeal under the variance procedure and shall be
determined, if necessary, on a case to case basis. However, as a general application,
expenditure for the accessory structure of not more than ten percent (10%) of the value
of the main structure shall be considered a minimal investment.
7-10-8: FLOOD INSURANCE STUDY: The flood insurance study for the City of Ammon,
dated April 2, 2002, and any revisions thereto, is hereby adopted by reference and declared to be
a part of the ordinance of the City of Ammon, for the control and use of property in the City of
Ammon, Idaho flood plain.
The most current flood insurance study for Bonneville County shall be used for any properties
annexed into the City of Ammon that are outside of the City of Ammon flood insurance study
maps.
7-10-9: ELEVATION CERTIFICATES REQUIRED FOR ALL NEW BUILDINGS IN THE
CITY:
Elevation Certificates for buildings in the floodplain shall be required at the following
times: Elevation Certificates for buildings in the floodplain should be required as follows:
Title 7, Chapter 10 Page 37 of 39 Revised 2-2021
(A) Submitted with construction drawings at the time of a request for a building permit
(prior to any alterations of the ground) and
(B) After the foundation or pad has been poured. This certificate should provide the
information showing the lowest floor is at or above the required elevation. The City
Engineer shall certify this.
(C) The City Engineer working with the Building Department shall inspect and certify
that any additional devices or structures are in place prior to the final certificate of
occupancy.
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Title 7, Chapter 10 Page 39 of 39 Revised 2-2021