The following definitions shall apply to words and phrases used in this division:
Accessory structure means a structure that is on the same parcel of property as a principal structure, the use of which is incidental to the use of the principal structure.
Appeal means a request for a review of the Floodplain Administrator's interpretation of any provision of this ordinance or a request for a variance.
Area of shallow flooding means a designated Zone AO or AH on a community's FIRM with a one (1) percent or greater annual chance of flooding to an average depth of one (1) to three (3) feet where a clearly defined channel does not exist, where the path of flooding is unpredictable, and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow.
Arizona Department of Water Resources (ADWR) is the state agency assigned with oversight of floodplain management/flood control as provided in Title 48, Chapter 21 of the Arizona Revised Statutes (A.R.S.).
Balanced basin means a drainage basin which contains floodwater channels, natural or manmade, and/or flood control structures that are adequate to contain existing runoff from the regulatory storm produced by the basin, but in which additional runoff cannot be safety contained by said channels or structures.
Base flood means the flood having a one (1) percent chance of being equaled or exceeded in any given year.
Base flood elevation (BFE) means the calculated water-surface elevation of the base flood. For a special flood hazard area, the BFE means the elevation shown on or calculated from the FIS or FIRM, including Zones A, AE, AO1, AO2, and AH, where the FIS or FIRM indicates the water surface elevation resulting from a base flood. FIS Profile shall be used when available. Other elevations shall be determined by an engineering study.
Basement means any area of the building having its floor subgrade (below ground level) on all sides.
Basin management plan means a site-specific plan for a watershed or balanced or critical basin which has been prepared for and approved by the city engineer, and which provides a conceptual plan for orderly development of flood control measures within the basin.
Breakaway wall means 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.
Building: See "Structure."
Community means any state, area or political subdivision thereof, or any Indian tribe or authorized tribal organization, or authorized native organization, which has authority to adopt and enforce floodplain management regulations for the areas within its jurisdiction.
Critical basin means a drainage basin which contains floodwater channels, natural or manmade, and/or flood control structures that cannot contain existing runoff produced by the regulatory flood within the basin, and which has a documented history of severe flooding hazards.
Critical facility means any new and substantially improved public or private facility, or any addition to an existing public or private facility, that is used for public emergency management or provides services and functions essential to the community. Critical facilities should be designed and constructed to be located outside of FEMA SFHA and other one hundred (100) year regulatory and five hundred (500) year floodplains. If a new development or substantially improved facility is proposed in a five hundred (500) year floodplain then the minimum building pad elevation shall be set at or above the five hundred (500) year water surface elevation, and the minimum lowest floor elevation shall be set at or above the five hundred (500) year water surface elevation plus one (1) foot, and provide all weather access for the five hundred (500) year flood condition. Critical facilities include: critical airport facilities (air traffic control towers, electrical vaults, emergency generators, police station, fire station, and fueling stations), emergency incident command centers, other emergency facilities including fire stations, police departments; utility facilities; nursing homes or elderly care facilities; hospitals; storage facilities that have hazardous materials; and schools or day care facilities. Other critical facilities may be designated as determined by city administration (department directors with city manager or designee's concurrence).
Cumulative improvement means the tracking of the market value of all improvements to a structure over a ten (10) year period for the purpose of determining substantial damage or improvement.
Detention system means a type of flood control system which delays the downstream progress of floodwaters in a controlled manner, generally through the combined use of a temporary storage area and a metered outlet device which causes a lengthening of the duration of flow and thereby reduces downstream flood peaks. Reduction of runoff shall be provided per current City of Tucson standards.
Development means any manmade change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, landscaping, paving, excavation, drilling operations, or storage of equipment or materials.
Drainage basin means any watershed or stormwater catchment land area, above a point on a watercourse which traverses the basin and to which the waters drain and collect.
Dry well means a device that is used to dispose of floodwaters through a process of passive infiltration of floodwaters into the vadose zone, below the ground surface. Unless specifically used for water re-charge, dry wells are restricted to post-construction drainage solutions where all drainage requirements are met.
Dwelling unit means a place of residence which may be located in a single- or multiple- dwelling building or a manufactured home.
Encroachment means the advancement or infringement of land uses, fill or structures, or development, into the floodplain that impedes, alters, or reduces the flow capacity of the channel and regulatory floodplain of a watercourse.
Erosion means the process, either rapid or gradual, of the wearing away of land masses by water flow forces. This peril is not, per se, covered under the National Flood Insurance Program (NFIP).
Erosion hazard area means the land area adjoining a watercourse regulated by this chapter which is deemed by the city engineer to be subject to FEMA or local flood-related erosion losses.
Exhibit 1. See exhibit 1 at end of this section.
Existing manufactured home park or subdivision means a manufactured home park for which the construction of facilities for servicing the lot on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, either final site grading or the pouring of concrete pads, and the construction of streets) is completed on or before March 22, 1982.
Expansion to an existing manufactured home park or subdivision means the preparation of additional sites by the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including the installation of utilities, either final site grading or pouring of concrete pads, or the construction of streets).
FEMA means the Federal Emergency Management Agency or designate successor agency that is responsible for the administration of the National Flood Insurance Program (NFIP) to provide flood insurance and to establish flood prone areas and development regulations.
Flood or flooding means a general and temporary condition of partial or complete inundation of normally dry land areas from (1) the overflow of floodwaters; (2) the unusual and rapid accumulation or runoff of surface waters from any source; and/or (3) 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 this definition.
Flood hazard map(s) (FHM) means an official map(s) of a community, issued by the city engineer, where the boundaries of the flood and/or related erosion hazard areas have been designated as local floodplain and/or erosion hazard zones.
Flood insurance rate map(s) (FIRM) means the official map(s) on which the Federal Emergency Management Agency has delineated both the areas of special flood hazards (SFHA) and the risk premium zones applicable to the community. These maps, which are approved by the city engineer and adopted by the floodplain board, provide information regarding floodplains of the city.
Flood insurance study (FIS) means the official report provided by FEMA that includes flood profiles, FIRM and the water surface elevation of the base flood as set forth in the FIS.
Floodplain or flood-prone area means any land area susceptible to being inundated by water from any source (see definition of "flood").
Floodplain administrator means the city engineer, or designee, who is the community official designated by title to administer and enforce the floodplain management regulations.
Floodplain board means the mayor and council at such times as they are engaged in the enforcement of this ordinance.
Floodplain and erosion hazard area management regulations means this ordinance and other zoning ordinances, subdivision regulations, building codes, health regulations, housing codes, setback requirements, open space area regulations, special purpose ordinances (such as a floodplain ordinance, grading ordinance and erosion control ordinance) and other applications of police power which control development in floodprone areas. The term describes such state or local regulations, in any combination thereof, which provide standards for preventing and reducing both erosion damage and flood loss and damage.
Floodplain management means the operation of an overall program of corrective and preventive measures for reducing flood damage and preserving and enhancing, where possible, natural resources in the floodplain, including but not limited to emergency preparedness plans, flood control works, floodplain management regulations, and open space plans.
Floodproofing means any combination of structural and nonstructural 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.
Floodplain use permit means an official document which authorizes specific activity within a regulatory floodplain or erosion hazard area.
Flood-related erosion means the collapse or subsidence of land along the shore of a lake, watercourse, or other body of water as a result of 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 a flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding.
Floodway or regulatory floodway means 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 a designated height. See exhibit 1.
Floodway encroachment lines mean the lines marking the limits of floodways on federal, state and local flood plain maps.
Floodway fringe means the land outside the floodway lying at or below the base flood elevation along a watercourse, and includes that area of the floodplain on either side of the regulatory floodway where encroachment may be permitted. See exhibit 1.
Freeboard means 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 of flood and floodway conditions, such as wave action, bridge openings, and the hydrological effect of urbanization of the watershed.
Functionally dependent use means a use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and ship building and ship repair facilities, and does not include long-term storage or related manufacturing facilities.
Governing body means the local governing municipality that is empowered to adopt and implement regulations to provide for the public health, safety and general welfare of its citizenry.
Hardship means, as related to section 26-12 of this ordinance, the exceptional hardship that would result from a failure to grant the requested variance. The City of Tucson mayor and council requires that the variance be exceptional, unusual, and peculiar to the property involved. Mere economic or financial hardship alone is not exceptional. Inconvenience, aesthetic considerations, physical handicaps, personal preferences, or the disapproval of one's neighbors likewise cannot, as a rule, qualify as an exceptional hardship. All of these problems can be resolved through other means without granting a variance, even if the alternative is more expensive, or requires the property owner to build elsewhere or put the parcel to a different use than originally intended.
Highest adjacent grade means the highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.
Historic structure means any structure that is:
(1) Listed individually in the National Register of Historic Places (a listing maintained by the department of the interior) or preliminarily determined by the secretary of the interior as meeting the requirements for individual listing in 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.
(4) Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either of the following:
a. By an approved state program as determined by the secretary of the interior.
b. Directly by the secretary of the interior in states without approved programs.
Levee means a man-made structure designed and constructed in accordance with sound engineering practices to contain, control, or divert the flow of water so as to reduce risk from temporary flooding. Classic levee includes concrete-encased earthen berms or soil cement structures with regulatory scour protection. A classic levee may also be a road/railroad prism meeting all FEMA levee requirements including compaction. A floodwall levee is a water-tight wall structure with regulatory scour protection meeting all FEMA levee requirements. Channel system levee is a structure constructed within a channel that meets FEMA levee requirements.
Lowest floor means 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 nonelevation design requirements of section 26-5.2 or 26-5.3 of this chapter. See definition of “Basement.”
Major wash or major watercourse means any watercourse which drains a contributing drainage basin of less than thirty (30) square miles and generates a base flood peak discharge of twenty-five hundred (2,500) cubic feet per second (cfs), or greater. Examples of major washes include but are not necessarily limited to: Alamo Wash, Cholla Wash, at and downstream from Mission Road, Pima Wash, Rodeo Wash, Silvercroft Wash, Tucson Arroyo, and West Branch of the Santa Cruz River Washes.
Manufactured home means a structure, transportable in one (1) 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" does not include a "recreational vehicle."
Manufactured home park or manufactured home subdivision means a parcel (or contiguous parcels) of land divided into two (2) or more manufactured home lots for rent or sale.
Market value is determined by estimating the cost to replace the structure in new condition and adjusting that cost figure by the amount of depreciation that has accrued since the structure was constructed. The cost of replacement of the structure shall be based on a square foot cost factor determined by reference to a building cost estimating guide recognized by the building construction industry. The amount of depreciation shall be determined by taking into account the age and physical deterioration of the structure and functional obsolescence as approved by the floodplain administrator, but shall not include economic or other forms of external obsolescence. Use of replacement costs or accrued depreciation factors different from those contained in recognized building cost estimating guides may be considered only if such factors are included in a report prepared by an independent professional appraiser and supported by a written explanation of the differences.
Mean sea level means, for purposes of the NFIP, the National Geodetic Vertical Datum (NGVD) of 1929, North American Vertical Datum (NAVD) of 1988, or other datum, to which base flood elevations shown on a community's FIRM's are referenced.
Minor watercourse or minor wash means a watercourse which conveys or collects a 100-year (base flood) peak discharge of less than twenty-five hundred (2,500) cubic feet per second (cfs), but more than one hundred (100) cfs.
New construction means, for purposes of determining insurance rates, structures for which the "start of construction" commenced on or after the effective date of August 2, 1982, when the FIRM became effective, and includes any subsequent improvements to such structures. For floodplain management purposes, "new construction" means structures for which the "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.
New manufactured home park or subdivision means a manufactured home park or subdivision for which 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 either final site grading or the pouring of concrete pads) is completed on or after the effective date of March 22, 1982, when floodplain management regulations were adopted by the city.
Obstruction means any matter, including but not limited to a dam, wall, wharf, embankment, levee, dike, pile, abutment, projection, excavation, channel rectification, bridge, conduit, culvert, building, wire, fence, rock, gravel, vegetation, refuse, fill, or structure in, along, across or projecting into any channel, watercourse, stream, lake or regulatory flood hazard area which may impede, alter, retard or change the direction of the flow of water, either in itself or by catching or collecting debris carried by such water, or that is placed where the flow of water might carry the same downstream to the damage of life or property.
One-hundred-year flood or 100-year flood is a common name for the flood having a one (1) percent chance of being equaled or exceeded in any given year. See definition of "Base flood."
Person means any individual or his agent, firm, partnership, association, corporation, or agent of the aforementioned groups, or the state, or any agency or political subdivision thereof.
Reach is a hydraulic engineering term to describe longitudinal segments of a watercourse.
Reclamation plan means a plan for sand and gravel operations which defined hydrological and hydraulic constraints; outlines methods of extraction, operation and site development; and provides for backfilling procedures and final site reclamation.
Recreational vehicle means a vehicle which is:
(1) Built on a single chassis;
(2) Four hundred (400) square feet or less when measured at the largest horizontal projections;
(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 a temporary living quarters for recreational, camping, travel or seasonal use.
Regional watercourse means a large watercourse, which may have intermittent flow, draining a contributing drainage basin of thirty (30) square miles or greater. Examples of regional watercourses include but are not necessarily limited to the Santa Cruz River, Rillito Creek, Pantano Wash, Tanque Verde Wash, and Canada Del Oro Wash.
Regulatory flood includes the base flood and drainage areas where the Q100 is equal to or greater than one hundred (100) cubic feet per second for the one (1) percent flood event.
Regulatory flood elevation means the elevation which is one (1) foot higher than the calculated water surface elevation of the base flood. In an AO Zone the RFE shall be one (1) foot higher than the depth number specified on the FIRM, or two (2) feet if no depth number is specified.
Regulatory floodplain means that portion of the natural floodplain that would be inundated by the regulatory flood. It includes that area where drainage is or may be restricted by manmade structures or those areas which are subject to sheet flooding, or those areas mapped as being floodprone on existing recorded subdivision plats and also includes areas where the Q100 is equal to or greater than one hundred (100) cubic feet per second for the one (1) percent flood event. Also see exhibit 1.
Regulatory floodway means 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 a designated height.
Repetitive loss property means any insurable building for which two (2) or more claims of more than one thousand dollars ($1,000) were paid by the National Flood Insurance Program (NFIP) within any rolling ten (10) year period, since 1978. At least two (2) of the claims must be more than ten (10) days apart but within ten (10) years of each other. A repetitive loss property may or may not be currently insured by the NFIP.
Retention system means a type of flood control facility which stores surface runoff and stops the downstream progress of surface water runoff or flood waters by employing methods of total containment such that the stored water infiltrates into the subsurface ground layers. No flow is discharged directly into a downstream watercourse from a retention system or basin, except for bleed pipes used for maintenance purposes only. Infiltration rates shall include a safety factor of two (2).
Setback means the minimum horizontal distance between a structure and a watercourse. On each side of a watercourse, the setback is measured from the top edge of the highest channel bank or edge of the base flood water surface elevation, whichever is closer to the channel center line.
Sheet flooding means those areas which are subject to flooding with depths of one-half ( 1/2) foot or greater during the base flood where a clearly defined channel does not exist and the path of the flooding is often unpredictable and indeterminate.
Special flood hazard area (SFHA) means an area of floodplain subject to a one (1) percent or greater chance of flooding in any given year. SFHA are shown on a FIRM as Zones A, AO(1), AO2, AE, or AH.
Start of construction includes substantial improvement and other proposed new development, and means the date the building permit was issued, provided the actual start of construction, repair, rehabilitation, addition, placement or other improvement was within one hundred eighty (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 below existing ground surface; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footings, piers, or foundations, or the erection of temporary forms. 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 means, for floodplain management purposes, a walled and/or roofed building, including a gas or liquid storage tank, that is principally above ground, as well as a manufactured home. "Structure" for insurance coverage purposes, means a walled and roofed building, other than a gas or liquid storage tank, that is principally above ground and affixed to a permanent site, as well as a manufactured home on a permanent foundation. For the latter purpose, the term includes a building while in the course of construction, alteration or repair, but does not include building materials or supplies intended for use in such construction, alteration or repair unless such materials or supplies are within an enclosed building on the premises.
Substantial damage means damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed fifty (50) percent of the market value of the structure before the damage occurred.
Substantial improvement means any reconstruction, repair, rehabilitation, addition or other improvement of a structure, the cost of which equals or exceeds fifty (50) percent 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 includes cost of improvements cumulatively added, in percentage, for a period of ten (10) years. 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 an "historic structure" provided that the alteration will not preclude the structure's continued designation as a "historic structure."
Variance means a grant of relief by the floodplain board from the requirements of this chapter which permits development in a manner that would otherwise be prohibited by the terms of this chapter.
Violation means the failure of a structure or other development to fully comply with the community's floodplain management regulations. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required in this ordinance is presumed to be in violation until such time as that documentation is provided to the city for review and acceptance.
Water surface elevation means the height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929, North American Vertical Datum (NAVD) of 1988, or other datum, of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas.
Watercourse means a lake, river, creek, stream, wash, arroyo, 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.
Watercourse master plan means a comprehensive plan adopted by the floodplain board that provides uniform, but separate, rules for watercourses where a higher level of protection is warranted for public safety or to preserve integrity of the watercourse, as provided by ARS Section 48-3609.01. These include the river and/or basin management plans, such as Tucson Stormwater Management Study (TSMS).
Watershed means "drainage basin." See definition of "drainage basin."
Zone A means no BFE's determined.
Zone AE means BFE's determined.
Zone AH means flood depths of one (1) to three (3) feet (usually areas of ponding); BFE's determined.
Zone AO means flood depths of one (1) to three (3) feet (usually sheet flow on sloping terrain); average depths determined. For areas of alluvial fan flooding, velocities also determined.
Zone X (unshaded) means areas determined to be outside the two-tenths (0.2) percent annual chance floodplain.
Zone X (shaded) means areas of two-tenths (0.2) percent annual chance flood; areas of one (1) percent annual chance flood with average depths of less than one (1) foot or with drainage areas less than one (1) square mile; and areas protected by levees from one (1) percent annual chance flood.
(Ord. No. 7407, § 5, 6-25-90; Ord. No. 10311, § 1, 8-8-06; Ord. No. 11396, § 1, 8-9-16; Ord. No. 11801, § 1, 12-8-20)
Cross References: Definitions and rules of construction, § 1-2.
