Last Modified on 05/07/2009 09:06:01Chapter 32B FLOODPLAINS*
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Cross references: Engineering and Architectural Services Department, § 2-27; Development Advisory Board, § 2-164 et seq.; building regulations, ch. 9; subdivisions, ch. 32; grading and drainage, ch. 32A.
State law references: Floodplain management, A.R.S. § 48-3601 et seq.; municipal floodplain management programs, A.R.S. § 48-3610.
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Article I. General
Sec. 32B-1. Implementation.
Sec. 32B-2. Definitions.
Article II. Regulations
Sec. 32B-3. Maps.
Sec. 32B-4. Classification of floodplains.
Sec. 32B-5. Regulation.
Sec. 32B-6. Interim elevations.
Sec. 32B-7. Coordination in floodplain management.
Sec. 32B-8. Non-prohibited construction.
Sec. 32B-9. Reserved.
Sec. 32B-9.1. Manufactured homes.
Sec. 32B-9.2. Mechanical and utility equipment.
Sec. 32B-9.3. Federal and State permits.
Sec. 32B-9.4. Openings in enclosures below a structure's lowest floor.
Sec. 32B-10. Sand and gravel operations.
Sec. 32B-11. Variance provisions.
Sec. 32B-12. Appeals.
Sec. 32B-13. Structures in violation of regulations.
Sec. 32B-14. Diversion of water flow.
Sec. 32B-15. Violation as separate offense.
Sec. 32B-16. Severability.
Sec. 32B-17. Floodplain plan review fees.
ARTICLE I.
GENERALSec. 32B-1. Implementation.
To implement the regulation of the floodplain areas in the City of Phoenix, the City Council is designated as the Floodplain Board and the City Engineer is designated as the administrative agent for these regulations.
(Ord. No. G-2027, § 2)
Sec. 32B-2. Definitions.
Area of shallow flooding means a designated zone in which 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 high velocity flow may be evident.
Area of special flood hazard means the land within a floodplain which is subject to inundation by the base flood.
Base flood means the flood having a one percent chance of being equalled or exceeded in any given year, i.e., the one-hundred-year flood.
Development means any manmade change to improved or unimproved real estate, including, but not limited to, buildings and other structures, utilities, pipelines, mining, dredging, filling, grading, paving, or excavation located within the area of special flood hazard.
Dwelling unit means any structure usable for residential purposes and which may be located in a single- or multiple-dwelling building, which includes working, sleeping, eating, cooking, recreation facilities, or a combination thereof, except a structure used only for storage purposes.
Flood or floodwaters means a temporary overflow of water on land not normally covered by water.
Flood boundary and floodway maps (FBFM) means the official map for the community on which the Federal Insurance Administration has delineated the area of special flood hazard and the selected floodway.
Flood insurance rate maps (FIRM) means the official maps on which the Federal Insurance Administration has delineated both the areas of special flood hazard and the risk premium insurance rates applicable to the community.
Flood insurance study means the official report provided by the Federal Insurance Administration that includes flood profiles, the flood boundary and floodway maps, and the water surface elevations of the base flood.
Floodplain means the relatively flat area adjoining the channel of a watercourse, or areas where drainage is or may be restricted by natural or manmade structures which may have been or may be covered partially or wholly by floodwater from a base flood.
Floodplain Board or Board means the City Council acting as the "Floodplain Board."
Floodway fringe area means that portion of the area of special flood hazard that is not included in the selected floodway.
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 non-elevation design requirements of this ordinance.
Manufactured home means 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 one hundred eighty 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 means a parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
Mean sea level means, for purposes of the National Flood Insurance Program, the National Geodetic Vertical Datum (NGVD of 1929) or other datum, to which base flood elevations shown on a community's flood insurance rate map are referenced.
Person means any individual or his agent, firm, partnership, association, corporation, or any agent of the aforementioned groups, or a federal, State, County or municipal government agency or political subdivision thereof.
Reasonable alteration or repair means any modification or improvement to existing facilities in which the total cost does not exceed fifty percent of the real cash value assessed at the commencement of construction. A reasonable alteration, however, should not be construed to mean any improvement which would increase the flood hazard to that property or the properties of surrounding homes.
Regulatory flood elevation means the elevation which is one foot above the "base flood" elevation for a "watercourse" for which the "base flood" elevation has been determined and shall be as determined by the criteria developed by the City Engineer for all other watercourses.
Selected floodway means the limits, as determined by the City Engineer, where the permitted encroachment in the floodplain will allow passage of the one-hundred-year flood without increasing the flood heights more than one foot. Additional hydraulic criteria such as maximum flow velocities of five feet per second at the limits of the selected floodway, smooth transitions around developments, and equal conveyance removal from each side will be used in computing the lines of the selected floodway.
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 one hundred eighty 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 state 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, footings, 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 part of the main structure.
Structure means a walled and roofed building or "manufactured home" that may or may not be habitable, may or may not be constructed on a permanent foundation, and was manmade.
Substantial improvement means any repair, reconstruction or improvement of a structure, the cost of which equals or exceeds fifty percent of the market value of the structure either before the improvement or if the structure was damaged and is being restored, before the damage occurred. A substantial improvement will not be permitted nor should it be construed to mean any modification which will increase flood hazard risk.
Violation means 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 required by this chapter is presumed to be in violation until such time as that documentation is provided.
Watercourse means any lake, river, creek, stream, wash, arroyo, channel, or other body of water having banks and bed through which waters flow at least periodically. The term may include specifically designated areas in which flood damage may occur.
(Ord. No. G-2027, § 2; Ord. No. G-3092, § 2)
Cross references: Definitions and rules of construction generally, § 1-2.
ARTICLE II.
REGULATIONSSec. 32B-3. Maps.
The areas of special flood hazard and the selected floodway for designated floodplains are shown on the current maps labeled "FIRM" and "Floodway," or as they may subsequently be amended, on file with the City Engineer, which maps are incorporated herein by reference. The maps are consistent with the criteria established by the Arizona Department of Water Resources and Federal Emergency Management Agency. New or additional engineering data may be considered for re-evaluation of floodplain and floodway delineations if circumstances indicate such action is in the public interest. Any such scientific or technical data will be submitted to the office of the City Engineer for review and conformance with established policy.
(Ord. No. G-2027, § 2; Ord. No. G-2641, § 1; Ord. No. G-3092, § 3)
Sec. 32B-4. Classification of floodplains.
To encourage the safe and orderly development of floodplain land, the Board recognizes that the floodplains consist of two distinct areas: the floodway fringe area having lower water velocities and shallower depths of flow and, the selected floodway which contains greater flow depths and damaging velocities. The Board also recognizes that encroachment into the floodway fringe area will not substantially increase the flood hazard to adjoining properties. It is also recognized that development and construction within the selected floodway will require higher standards of engineering and construction than development within the floodway fringe area in order to insure that there is no substantial hazard to such development or construction and that it does not create a substantial hazard to other property within the floodplain.
(Ord. No. G-2027, § 2)
Sec. 32B-5. Regulation.
In order to promote the public health, safety and general welfare, the Floodplain Board will enforce the following regulations:
1. No person may either obstruct, divert, or reduce the capacity within the area of special flood hazard by constructing any development or altering the width or course of said floodways except as provided in these regulations.
2. Construction and development may occur within the floodway fringe and the areas of shallow flooding provided that the City Engineer review and approve all such requests for building permits prior to issuance by the Building Official. The City Engineer will ascertain that the proposed construction will incorporate appropriate floodproofing measures to the "regulatory flood elevation," or that the "lowest floor" is above the "regulatory flood elevation." A "dwelling unit" shall be so constructed so as to place the "lowest floor" elevation of the "dwelling unit" above the "regulatory flood elevation." Appropriate floodproofing measures may include, but not be limited to: providing access during flood events, maintaining electrical, water, and sewer services, designing foundations and structures to withstand hydraulic loadings expected during the base flood and designing windows, doorways and other openings located below the level of the base flood to prevent the entrance of floodwaters. Any applicant for a building permit has the burden of furnishing the Development Services Director satisfactory evidence to enable him to either determine that the applicant's property does not fall within the area of special flood hazard or that there is no substantial hazard, either to the proposed development or to the property.
3. Construction and development may be permitted within the selected floodway subject to review and approval by the City Engineer, on an individual permit basis; however, no development in the selected floodway will be allowed which will increase the water surface elevation of the base flood.
4. These regulations do not affect the existing use of property in the areas of special flood hazard or the right to the continuation of that use, nor do they affect the reasonable repair or alteration of property for the purpose for which such property was lawfully used on February 12, 1974.
5. Any substantial improvements to existing structures must conform to the requirements of this chapter.
6. New developments which provide on-site waste disposal systems must locate them outside the boundary of the base flood.
7. Within one hundred twenty days after completion of any flood control project, the areas of special flood hazard and the selected floodway in the area benefited by such works will be redefined.
8. Any new building or development located or maintained within the area of special flood hazard must have prior written authorization from the City Engineer, except as specified in 32B-8 and 32B-10 of these regulations.
9. The owner must have a registered professional engineer, or registered land surveyor, certify to the Development Services Director the actual elevation of the minimum finished floor of any new or substantially improved structure located within the area of special flood hazard. A record of these certifications shall be maintained with the Development Services Director. In addition, where a nonresidential structure is intended to be made watertight below the base flood level, a registered professional engineer or registered architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with accepted standards of practice for meeting the applicable provisions of this section. A record of such certification which includes the specific elevation (in relation to mean sea level) to which such structures are floodproofed shall be maintained with the Development Services Director.
10. The City Engineer and the Development Services Director will obtain and maintain for public inspection, all records pertaining to the provisions of this ordinance.
11. No development shall increase the one-hundred-year twenty-four-hour peak or the one-hundred-year two-hour peak whichever is higher. Nor shall the time of the peak change or the total runoff exceed the pre-development total runoff.
12. In areas of special flood hazard without a selected floodway or its flood insurance rate map (FIRM) [or] flood insurance flood boundary and floodway maps (FBFM): No new flood boundary and floodway maps, construction, substantial improvements, or other development (including fill) shall be permitted unless it is demonstrated that the cumulative effect of the proposed developments, when combined with all other existing and proposed developments will not increase the water surface elevation of the base flood more than one foot at a point within the community.
(Ord. No. G-2027, § 2; Ord. No. G-3092, § 4; Ord. No. G-3313, § 1)
Sec. 32B-6. Interim elevations.
When base flood elevations and delineations are not available due to recent annexation or other causes, the City Engineer may obtain, review, and reasonably utilize any base flood elevation data available from a federal, State, County or other political subdivision for the purpose of securing a base flood determination, until such time as the Federal Emergency Management Agency has published the final FIRM (flood insurance rate maps) and FBFW (flood boundary and floodway maps).
(Ord. No. G-2027, § 2; Ord. No. G-3313, § 1)
Sec. 32B-7. Coordination in floodplain management.
The Floodplain Board may adopt other regulations which provide for coordination with all other interested and affected political subdivisions and State agencies and may enter into agreements for cooperative regulations, planning, designs, and construction. The Development Services Director shall advise the Flood Control District of Maricopa County and any other adjacent jurisdiction having responsibility for floodplain management, in writing, and provide a copy of any development plan of all applications for floodplain use permits or variances to develop land in a floodplain or floodway within one mile of the boundary between the City's area of jurisdiction and the area of jurisdiction of the District. The Development Services Director shall also advise the District and any adjacent jurisdiction having responsibility for floodplain management in writing and provide a copy of any development plan of any major development proposed within a floodplain or floodway which could affect floodplains, floodways or watercourses outside the City's area of jurisdiction. Written notice and a copy of the plan of development shall be sent to any adjacent jurisdiction no later than three working days after having been received.
(Ord. No. G-2027, § 2; Ord. No. G-3092, § 5; Ord. No. G-3313, § 1)
Sec. 32B-8. Non-prohibited construction.
Written authorization shall not be required nor shall the Floodplain Board prohibit:
1. The construction of bridges, culverts, dikes, and other structures necessary to the construction of public highways, roads, and streets intersecting or crossing a watercourse.
2. The construction of storage dams for watering livestock or wildlife structures on banks of a creek, stream, river, wash, arroyo or other watercourses to prevent erosion of or damage to adjoining land, or dams for the conservation of floodwaters as permitted by A.R.S. tit. 45, ch. 3.1 (A.R.S. § 45-801.01 et seq.).
3. Construction of tailing dams and waste disposal areas for use in connection with mining and metallurgical operations.
(Ord. No. G-2027, § 2)
Sec. 32B-9. Reserved.
Editor's note: Section 32B-9 was repealed; see Ord. No. G-3092, § 6.
Sec. 32B-9.1. Manufactured homes.
Any manufactured homes to be placed within the area of special flood hazard shall be installed using methods and practices which minimize flood damage. For the purposes of this requirement, manufactured homes must be elevated so that the bottom of the structural frame or the lowest point of any attached appliances, whichever is lower, is at or above the regulatory flood elevation and anchored to resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors. This requirement is in addition to applicable State requirements.
(Ord. No. G-3092, § 6)
Sec. 32B-9.2. Mechanical and utility equipment.
Electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities shall be designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
(Ord. No. G-3092, § 6)
Sec. 32B-9.3. Federal and State permits.
All development located within an area of special flood hazard shall obtain all permits required by State and federal law, specifically that required by section 404 of the Federal Water Pollution Control Amendments of 1972.
(Ord. No. G-3092, § 6)
Sec. 32B-9.4. Openings in enclosures below a structure's lowest floor.
For all new construction and substantial improvements, fully enclosed areas below the lowest floor that are subject to flooding 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:
A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
(Ord. No. G-3092, § 6)
Sec. 32B-10. Sand and gravel operations.
Sand and gravel operations are allowed within the floodplain subject to the following conditions:
1. Within the selected floodway, sand and gravel operations may be conducted without permit provided that:
(a) The operations are restricted to [the] extraction of sand and gravel for commercial purposes; and
(b) Excavations are not so located nor of such depth as to present a hazard to other development, including, but not limited to, roads, bridges, culverts, and utilities.
2. No stockpiling, within the selected floodway, of material or tailings that may obstruct, divert, or retard the flow of floodwaters will be permitted except as reviewed and approved by the City Engineer, on an individual permit basis.
3. Stockpiling of sand and gravel products within the floodway fringe area may be done without permit provided that the operator furnishes the City Engineer satisfactory evidence that such stockpiling is within the floodway fringe area rather than in the selected floodway.
4. Excavations for sand and gravel for commercial purposes within the floodway fringe area which exceed the definitions contained in section 32A-6, paragraph (b)(1) [sic] (Grading and Drainage) of the City Code will be permitted subject to review and approval by the City Engineer, on an individual permit basis.
(Ord. No. G-2027, § 2)
Sec. 32B-11. Variance provisions.
A. The City Engineer may authorize variances from the terms of this chapter when a literal enforcement of any provisions of this ordinance would result in an unnecessary property hardship and when evidence is presented demonstrating to the satisfaction of the City Engineer that all of the following conditions are fulfilled:
1. That special conditions and circumstances exist which are peculiar to the land or structure involved and which are not applicable to other lands or structures within the same general area such as a new structure to be erected on a lot of one-half acre or less, contiguous to and surrounded by lots with existing structures built below the level of the base flood; and
2. That the alleged hardships caused by literal interpretation of the provisions of this chapter are property hardships which include more than personal inconvenience and financial hardships, and do not result from the action of the owner or the applicant; and
3. That the variances will not be detrimental to persons residing or working in the vicinity and to adjacent property, to the neighborhood and to the public welfare in general; and
4. That the variance is the minimum variance that will make possible the reasonable use of the land or structure; and
5. That appropriate and specific conditions have been stipulated by the City Engineer in connection with the variances as may be deemed necessary in order to fully carry out the intent of the Floodplain Ordinance. The stipulation may include, among other things, a requirement that the applicant insert a note on any future deed or other conveyance of the property stating that the property is located in a floodprone area. The notice will include the number of feet that the lowest non-floodproofed floor of the proposed structure is below the base flood level and a statement that the actuarial flood insurance rates increase as the first floor elevation decreases. A violation of any condition shall be considered a violation of the Floodplain Ordinance and such violation shall render the variance null and void; and
6. That the burden of proof in all matters heard by the City Engineer shall rest with the applicant. The granting of a variance is a matter of grace, resting on the discretion of the City Engineer, and a refusal is not a denial of a right, conditional or otherwise.
B. A variance will be issued for the reconstruction, rehabilitation, or restoration of all structures listed on the National or State Register of Historic Places or the State inventory of historic places, without regard to conflicting procedures and provisions set forth in this section.
(Ord. No. G-2027, § 2)
Sec. 32B-12. Appeals.
Appeals from decisions of the City Engineer in application of these regulations may be taken to the Development Advisory Board acting as the Floodplain Appeal Board. Any person aggrieved by a decision of the Floodplain Appeal Board may bring special action in a court of competent jurisdiction. The Floodplain Appeal Board, when reviewing an appeal from a decision of the City Engineer, shall follow the rules and standards set forth in this ordinance.
(Ord. No. G-2027, § 2; Ord. No. G-3313, § 1; Ord. No. G-4176, § 13, passed 5-19-1999, eff. 6-18-1999)
Sec. 32B-13. Structures in violation of regulations.
Except as provided in paragraphs 32B-8 and 32B-10, all new development located or maintained within any area of special flood hazard in violation of the regulations of this chapter and without written authorization from the Floodplain Board or the City Engineer as administrative agent of the Floodplain Board is hereby declared to be a public nuisance per se and may be abated, prevented or restrained by action of the City.
(Ord. No. G-2027, § 2)
Sec. 32B-14. Diversion of water flow.
A. It is unlawful for any person to divert, retard, or obstruct any watercourse in the City of Phoenix whenever such action creates a hazard to life or property without securing the written authorization required by the preceding regulations.
B. Any person violating the provisions of this section shall be guilty of a misdemeanor.
(Ord. No. G-2027, § 2)
Sec. 32B-15. Violation as separate offense.
Each day of violation of these regulations shall constitute a separate offense.