The following definitions are specifically applicable to floodplain management and supplement those set forth in § 154.003 Definitions of Chapter 154: Zoning Code.
APPURTENANT OR ACCESSORY STRUCTURE. A non-residential structure which is on the same parcel of property as the principal structure and the use of which is incidental to the use of the principal structure. Accessory structures are not to exceed 600 square feet.
BASE FLOOD. The flood having a 1% chance of being equaled or exceeded in any given year.
BASE FLOOD ELEVATION. The water surface elevations of the base flood, that is, the flood level that has a 1% or greater chance of occurrence in any given year. The water surface elevation of the base flood in relation to the datum specified on the community's Flood Insurance Rate Map. For the purposes of this chapter, the base flood is the 1% annual chance flood.
BASEMENT. Any area of the building having its floor sub-grade (below ground level) on all sides.
BREAKAWAY WALL. A wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces, without causing damage to the elevated portion of the building or supporting foundation system.
COASTAL A ZONE. Flood hazard areas that have been delineated as subject to wave heights between 1.5 feet and three feet. The LiMWA designates the 1.5 foot wave.
COASTAL HIGH HAZARD AREA. That part of the coastal floodplain extending from offshore to the inland limit of the primary coastal dune along an open coast and any other area subject to high velocity wave action from storms and seismic sources. Wave heights during the base flood will generally be three feet or more in height above the still water elevation.
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 or storage of equipment or materials.
ELEVATED BUILDING. A non-basement building built to have the lowest floor elevated above the ground level by means of fill, solid foundation perimeter walls, pilings, or columns (posts and piers).
ENCROACHMENT. The advance or infringement of uses, plant growth, fill, excavation, buildings, permanent structures, or development into a floodplain, which may impede or alter the flow capacity of a floodplain.
EXISTING CONSTRUCTION. Structures for which the "start of construction" commenced before August 11, 1976. EXISTING CONSTRUCTION may also be referred to as EXISTING STRUCTURES and PRE-FIRM.
FLOOD or FLOODING.
(1) A general or temporary condition of partial or complete inundation of normally dry land areas from the overflow of inland or tidal waters or the unusual and rapid accumulation or runoff of surface waters from any source.
(2) The collapse or subsistence 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 division (1) above of this definition.
FLOOD INSURANCE RATE MAP (FIRM). An official map of a community, on which the Federal Emergency Management Agency has delineated both the special hazard areas and the risk premium zones applicable to the community. A FIRM that has been made available digitally is called a DIGITAL FLOOD INSURANCE RATE MAP (DFIRM).
FLOOD INSURANCE STUDY (FIS). A report by FEMA that examines, evaluates and determines flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation and
determination of mudflow and/or flood-related erosion hazards.
FLOODPLAIN or FLOOD-PRONE AREA. Any land area susceptible to being inundated by water from any source.
FLOOD PROOFING. 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.
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 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, bridge openings, and the hydrological effect of urbanization in the watershed.
FUNCTIONALLY DEPENDENT USE. A use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. This term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and shipbuilding and ship repair facilities, but does not include long-term storage or related manufacturing facilities.
HIGHEST ADJACENT GRADE. The highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.
HISTORIC STRUCTURE. Any structure that is:
(1) Listed individually in the National Register of Historic Places (a listing maintained by the Department of Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;
(2) Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;
(3) Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of the Interior; or
(4) Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either by an approved state program as determined by the Secretary of the Interior or directly by the Secretary of the Interior in states without approved programs.
HYDROLOGIC AND HYDRAULIC ENGINEERING ANALYSIS. Analyses performed by a licensed professional engineer, in accordance with standard engineering practices that are accepted by the Virginia Department of Conservation and Recreation and FEMA, used to determine the base flood, other frequency floods, flood elevations, floodway information and boundaries, and flood profiles.
LETTER OF MAP CHANGE (LOMC). An official FEMA determination, by letter, that amends or revises an effective Flood Insurance Rate Map or Flood Insurance Study. LETTERS OF MAP CHANGE include:
(1) LETTER OF MAP AMENDMENT (LOMA). An amendment based on technical data showing that a property was incorrectly included in a designated special flood hazard area. A LOMA amends the current effective Flood Insurance Rate Map and establishes that a land as defined by meets and bounds or structure is not located in a special flood hazard area.
(2) LETTER OF MAP REVISION (LOMR). A revision based on technical data that may show changes to flood zones, flood elevations, floodplain and floodway delineations, and planimetric features. A LETTER OF MAP REVISION BASED ON FILL (LOMR-F), is a determination that a structure or parcel of land has been elevated by fill above the base flood elevation and is, therefore, no longer exposed to flooding associated with the base flood. In order to qualify for this determination, the fill must have been permitted and placed in accordance with the county's floodplain management regulations.
(3) 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 or Flood Insurance Study.
LOWEST ADJACENT GRADE. The lowest natural elevation of the ground surface next to the walls of a structure.
LOWEST FLOOR. The lowest floor of the lowest enclosed area (including basement). An unfinished or flood-resistant 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 Federal Code 44 C.F.R. 60.3.
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 MANUFACTURED HOME also includes park trailers, travel trailers, and other similar vehicles placed on a site for greater than 180 consecutive days.
MANUFACTURED HOME PARK OR SUBDIVISION. A parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
MEAN SEA LEVEL. For purposes of the National Flood Insurance Program, the National Geodetic Vertical Datum (NGVD) of 1929 or the North American Vertical Datum (NAVD) of 1988 to which base flood elevations shown on a community's FIRM are referenced.
NEW CONSTRUCTION. For the purposes of determining insurance rates, structures for which the start of construction commenced on or after August 11, 1976, and includes any subsequent improvements to such structures. For floodplain management purposes, NEW CONSTRUCTION means structures for which start of construction commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such structures.
POST FIRM STRUCTURE. A structure for which construction or substantial improvement occurred after August 11, 1976.
PRE-FIRM STRUCTURES. A structure for which construction or substantial improvement occurred on or before August 11, 1976.
PRIMARY FRONTAL DUNE. A continuous or nearly continuous mound or ridge of sand with relatively steep seaward and landward slopes immediately landward and adjacent to the beach and subject to erosion and overtopping from high tides and waves during major coastal storms. The inland limit of the PRIMARY FRONTAL DUNE occurs at the point where there is a distinct change from a relatively steep slope to a relatively mild slope.
RECREATIONAL VEHICLE. A vehicle which is:
(1) Built on a single chassis;
(2) Four hundred square feet or less when measured at the largest horizontal projection;
(3) Designed to be self-propelled or permanently towable by a light duty truck; and
(4) Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational camping, travel, or seasonal use.
REPETITIVE LOSS STRUCTURE. A building covered by a contract for flood insurance that has
incurred flood-related damages on two occasions in a ten-year period, in which the cost of the repair, on the average, equaled or exceeded 25% of the market value of the structure at the time of each such flood event; and at the time of the second incidence of flood-related damage, the contract for flood insurance contains increased cost of compliance coverage.
SEVERE REPETITIVE LOSS STRUCTURE. A structure that:
(1) Is covered under a contract for flood insurance made available under NFIP; and
(2) Has incurred flood related damage -
(a) For which four or more separate claim payments have been made under flood insurance coverage with the amount of each such claim exceeding $5,000, and with the cumulative amount of such claims payments exceeding $20,000; or
(b) For which at least two separate claims payments have been made under such coverage, with the cumulative amount of such claims exceeding the market value of the insured structure.
SHALLOW FLOODING AREA. A special flood hazard area with base flood depths from one to three feet where a clearly defined channel does not exist, where the path of flooding is unpredictable and indeterminate, and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow.
SPECIAL FLOOD HAZARD AREA. The land in the floodplain subject to a 1% or greater chance of being flooded in any given year as determined in § 159.107 of this chapter.
START OF CONSTRUCTION. For other than new construction and substantial improvement, under the Coastal Barriers Resource Act (P.L. 97-348), means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition, placement, substantial improvement or other improvement is 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 slab 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 on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main structure. For a substantial improvement, the ACTUAL START OF THE 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. For floodplain management purposes, 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% of the market value of the structure before the damage occurred.
SUBSTANTIAL IMPROVEMENT. Any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 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:
(1) 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
(2) Any alteration of a historic structure, provided that the alteration will not preclude the structure's continued designation as a historic structure.
(3) Historic structures undergoing repair or rehabilitation that would constitute a substantial improvement as defined above, must comply with all ordinance requirements that do not preclude the structure's continued designation as a historic structure. Documentation that a specific ordinance requirement will cause removal of the structure from the National Register of Historic Places or the State Inventory of Historic Places must be obtained from the Secretary of the Interior or the State Historic Preservation Officer. Any exemption from ordinance requirements will be the minimum necessary to preserve the historic character and design of the structure.
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 elevation certificate, other certifications, or other evidence of compliance is presumed to be in violation until such time as that documentation is provided.
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.
(Ord. passed 2-23-2015; Am. Ord. passed 5-12-2015; Am. Ord. passed 10-10-2023)