Chapter 12

 

                                           DRAINAGE AND FLOOD CONTROL[1]

 

                                                    Art. I.          In General, §§ 12-1—12-15

                                                   Art. II.          Floodplain Management, §§ 12-16—12-35

                                                 Art. III.          Salt River Flood Channel, §§ 12-36—12-55

                                                 Art. IV.          Storm Water Retention, §§ 12-56—12-100

                                                                         Div. 1.  Generally, §§ 12-56—12-70

                                                                         Div. 2.  Administration, §§ 12-71—12-85

                                                                         Div. 3.  Standards and Specifications, §§ 12-86—12-100

                                                   Art. V.          Storm Water System Extension Policy, §§ 12-101—12-105

                                                 Art. VI.          Storm Water Pollution Control, §§ 12-115—12-152

                                                                         Div. 1.  General Provisions, §§ 12-115—12-124

                                                                         Div. 2.  Prohibitions and Controls to Reduce the Discharge of Pollutants

                                                                                        in Storm water, §§ 12-125—12-134

                                                                         Div. 3.  Compliance Monitoring, §§ 12-135—12-144

                                                                         Div. 4.  Enforcement, §§ 12-145—12-152

 

                                                     ARTICLE I.  IN GENERAL

 

Secs. 12-1—12-15.  Reserved.

 

                                   ARTICLE II.  FLOODPLAIN MANAGEMENT [2]

 

Sec. 12-16.  Purpose.

 

         (a)     The flood hazard areas of Tempe are subject to periodic inundation which can result 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.

 

         (b)     These flood losses are caused by the cumulative effect of obstructions in areas of special flood hazard 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.

 

         (c)     It is the purpose of this article to promote the public health, safety and general welfare, and to minimize public and private losses due to flood conditions in specific areas by provisions designed:

 

                  (1)     To protect human life and health;

 

                  (2)     To minimize expenditure of public money for costly flood-control projects;

 


                  (3)     To minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;

 

                  (4)     To minimize prolonged business interruptions;

 

                  (5)     To minimize damage to public facilities and utilities, such as water and gas mains, electric, telephone and sewer lines, and streets and bridges, located in areas of special flood hazard;

 

                  (6)     To help maintain a stable tax base by providing for the second use and development of areas of special flood hazard so as to minimize future flood blight areas;

 

                  (7)     To ensure that potential buyers are notified that property is in an area of special flood hazard;

 

                  (8)     To ensure that those who occupy the areas of special flood hazard assume responsibility for their actions; and

 

                  (9)     To maintain eligibility for state disaster relief.

(Ord. No. 87.25, 9-10-87)

 

Sec. 12-17.  Methods of reducing flood losses.

 

         In order to accomplish its purposes, this article includes methods and provisions for:

 

                  (1)     Restricting or prohibiting uses which are dangerous to health, safety and property due to water or erosion hazards, or which result in damaging increases in erosion or in flood heights or velocities;

 

                  (2)     Requiring that uses vulnerable to floods, including facilities which serve such uses, be protected against flood damage at the time of initial construction;

 

                  (3)     Controlling the alteration of natural floodplains, stream channels and natural protective barriers, which help accommodate or channel floodwaters;

 

                  (4)     Controlling filling, grading, dredging and other development which may increase flood damage; and

 

                  (5)     Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or which may increase flood hazards in other areas.

(Ord. No. 87.25, 9-10-87)

 


Sec. 12-18.  Definitions.

 

         Unless specifically defined below, words or phrases used in this article shall be interpreted so as to give them the meaning they have in common usage and to give this article its most reasonable application:

 

         Appeal means a request for a review of the floodplain administrator's interpretation of any provision of this article.

 

         Area of shallow flooding means a designated AO Zone on the flood insurance rate map (FIRM). The base flood depths range from one to three (3) feet, a clearly defined channel does not exist, the path of flooding is unpredictable and indeterminate, and velocity flow may be evident.

 

         Base flood means the flood having a one percent chance of being equaled or exceeded in any given year.

 

         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 supporting foundation system.

 

         Critical feature means an integral and readily identifiable part of a flood protection system without which the flood protection provided by the entire system would be compromised.

 

         Development means 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.

 

         Financial assistance means any form of loan, grant, guaranty, insurance, payment, rebate, subsidy, disaster assistance loan or grant, or any other form of direct or indirect federal assistance, other than general or special revenue sharing or formula grants made to states.

 

         Flood or flooding means a general and temporary condition of partial or complete inundation of normally dry land areas from the overflow of flood water; the unusual and rapid accumulation or runoff of surface waters from any source; or the collapse or subsidence of land along the shore of a body of water as a result of an unanticipated force of nature, such as flash flood, or by some similarly unusual and unforeseeable event which results in flooding as defined in this definition.

        

         Flood boundary floodway map means the official map on which the Federal Insurance Administration has delineated both the areas of flood hazard and the floodway.

 

         Flood insurance rate map (FIRM) means 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.

 

         Flood insurance study means the official report provided by the Federal Insurance Administration that includes flood profiles, the FIRM, the flood boundary floodway map, and the water surface elevation of the base flood.

         Floodplain or flood-prone area means any land area susceptible to being inundated by water from any source (see definition of "Flooding").

 

         Floodplain administrator means the city engineer of the city who is hereby authorized by the floodplain board to administer the provisions of this article.

 

         Floodplain board means the city council of the city at such times as they are engaged in the enforcement of this article.

 

         Floodplain management means 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 means zoning ordinances, subdivision regulations, building codes, health regulations, special purpose ordinances (such as floodplain ordinances, grading ordinances and erosion control ordinances) 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.

 

         Flood proofing 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.

 

         Flood protection system means 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 in conformance with sound engineering standards.

 

         Flood-related erosion means the collapse or subsidence of land along a body of water as a result of an unanticipated force of nature, such as a flash flood, or by some similarly unusual and unforeseeable event which results in flooding.

 

         Floodway means the channel of a river or other watercourse and the adjacent land areas necessary in order to discharge the 100-year flood without cumulatively increasing the water surface elevation.

 

         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, but does not include long-term storage or related manufacturing facilities.

 

         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 a structure listed on the National Register of Historic Places or in a state or local inventory of historic places.

         Levee means a man-made structure, usually an earthen embankment, designed and constructed in accordance with sound engineering practices to contain, control or divert the flow of water so as to provide protection from temporary flooding.

 

         Levee system means a flood protection system which 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 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 this article.

 

         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.  The term "manufactured home" does not include a "recreational vehicle".

 

         Manufactured home park or subdivision means a parcel (or contiguous parcels) of land divided into two (2) or more manufactured home lots for sale or rent.

 

         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.

 

         New construction means, for floodplain management purposes, 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.

 

         Person means an individual or his agent, a firm, partnership, association or corporation or agent of the aforementioned groups, or this state or its agencies or political subdivisions.

 

         Program means the National Flood Insurance Program authorized by 42 U.S.C. §§ 4001—4128.

 

         Program deficiency means a defect in a community's floodplain management regulations or administrative procedures that impairs effective implementation of those floodplain management regulations or of the NFIP standards.

 

         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 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.

 

         Regulatory flood-elevation means an elevation one foot above the base flood elevation indicated on the FIRM. For example, buildings in Zone "AO (one foot depth)" are required to have the lowest floor two (2) feet higher than the highest adjacent grade.

 

         Remedy a violation means 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 noncompliance.  Ways that impacts may be reduced include protecting the structure or other affected development from flood damages, implementing the enforcement provisions of this article or otherwise deterring future similar violations, or reducing federal financial exposure with regard to the structure or other development.

 

         Riverine means relating to, formed by, or resembling a river (including tributaries), stream, brook, etc.

 

         Special flood hazard area means an area having special flood or flood-related erosion hazards, and shown on an FHBM or FIRM as Zone A, AO, A1-30, AE, A99 or AH.

 

         Start of construction includes substantial improvement, and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, 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 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 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.  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 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 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 percent (50%) of the market value of the structure before the damage occurred.

 

         Substantial improvement means any repair, reconstruction, rehabilitation, addition 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:

 

                  (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".

 

         Variance means a grant of relief from the requirements of this article which permits construction in a manner that would otherwise be prohibited by this article.

 

         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 in this article is presumed to be in violation until such time as that documentation is provided.

(Ord. No. 87.25, 9-10-87; Ord. 2005.67, 9-29-05)

 

Sec. 12-19.  Compliance and jurisdiction of this article.

 

         (a)     This article shall apply to all areas of special flood hazards within the corporate limits of Tempe.  No structure or land shall hereafter be constructed, located, extended, converted or altered without full compliance with the terms of this article and other applicable regulations.

 

         (b)     Within a delineated floodplain, the development services department shall not issue a building permit until receipt of notification from the floodplain administrator that all plans have been reviewed and approved for conformance with this article.

 

         (c)     Within a delineated floodplain, the development services department shall not issue a certificate of occupancy until receipt of notification from the floodplain administrator that all construction has been completed in conformance with this article.

(Ord. No. 87.25, 9-10-87; Ord. No. 97.20, 4-10-97)

 

Sec. 12-20.  Basis for establishing the areas of special flood hazard.

 

         The area of special flood hazard identified by the Federal Emergency Management Agency (FEMA) in a scientific and engineering report entitled "The Flood Insurance Study for Maricopa County and Incorporated areas" dated July 19, 2001, with an accompanying flood insurance rate map and all subsequent amendments or revisions are adopted by reference and declared to be a part of this article.  The flood insurance study and the flood insurance rate maps are on file at the city engineering office.  The flood insurance study is the minimum area of applicability of this article and may be supplemented by studies for other areas which allow implementation of this article and which are recommended to the floodplain board by the floodplain administrator.  The floodplain board, within its area of jurisdiction shall delineate (or may, by rule, require developers of land to delineate) for areas where development is ongoing or imminent, and thereafter as development becomes imminent, floodplains consistent with the criteria developed by FEMA and the director of water resources.

(Ord. No. 87.25, 9-10-87; Ord. No. 2005.67, 9-29-05)

 


Sec. 12-21.  Abrogation and greater restrictions.

 

         This article is not intended to repeal, abrogate or impair any existing easements, covenants or deed restrictions.  However, where this article and another ordinance, easement, covenant or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.

(Ord. No. 87.25, 9-10-87)

 

Sec. 12-22.  Interpretation.

 

         In the interpretation and application of this article, all provisions shall be considered as minimum requirements, liberally construed in favor of the governing body, and deemed neither to limit nor repeal any other powers granted under state statutes.

(Ord. No. 87.25, 9-10-87)

 

Sec. 12-23.  Warning and disclaimer of liability.

 

         The degree of flood protection required by this article 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 article 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 article shall not create liability on the part of the city, any officer or employee thereof, or the Federal Insurance Administration for any flood damages that result from reliance on this article or any administrative decision lawfully made thereunder.

(Ord. No. 87.25, 9-10-87)

 

Sec. 12-24.  Statutory exemptions.

 

         (a)     In accordance with A.R.S. § 48-3609, nothing in this article shall:

 

                  (1)     Affect existing uses of property or the right to continuation of the use under conditions which existed on the effective date of this article;

 

                  (2)     Affect repair or alteration of property for the purposes for which such property was used on the effective date of this article; providing such repair or alteration does not exceed fifty percent (50%) of the value of the property prior to the repair or alteration; and provided the repair or alteration does not decrease the carrying capacity of the watercourse; or

 

                  (3)     Affect or apply to facilities constructed or installed pursuant to a certificate or environmental compatibility issued under the authority of Title 40, Chapter 2, Article 6.2.

 

         (b)     In accordance with A.R.S. § 48-3613, written authorization shall not be required, nor shall the floodplain board prohibits:

 

                  (1)     The construction of bridges, culverts, dikes and other structures necessary to the construction of public highways, roads and streets intersecting a watercourse;

                 

                  (2)     The construction of structures on banks of a creek, stream, river, wash, arroyo or other watercourse to prevent erosion of or damage to adjoining land, or dams for the conservation of floodwaters as permitted by Title 48, Chapter 21;

 

                  (3)     Construction of tailing dams and waste disposal areas for use in connection with mining and metallurgical operations.  This paragraph does not exempt those sand and gravel operations which will divert, retard or obstruct the flow of waters in any watercourse; or

 

                  (4)     Any flood-control district, or other political subdivision, from exercising powers granted to it under Title 45, Chapter 10, Arizona Revised Statutes.

 

         (c)     Before any construction authorized by paragraph (b) above may begin, the responsible person must submit plans for the construction to the floodplain administrator for review and comment.

 

         (d)    These exemptions do not preclude any person from liability if that person's actions increase flood hazards to any other person or property.

(Ord. No. 87.25, 9-10-87)

 

Sec. 12-25.  Violations.

 

         (a)     It is unlawful for any person to divert, retard or obstruct the flow of waters in any watercourse whenever it creates a hazard to life or property.

 

         (b)     Violators of this article shall be notified in writing by the city engineer.  The notice, which shall be sent by certified mail or personally served, shall state specifically the nature of the violation and request that it be corrected.  If a violation is not corrected within thirty (30) days after notice, the city engineer shall promptly hand over all pertinent facts to the city attorney with a request for prosecution under the provisions of this article.  Any persons violating any of the provisions of this article shall be guilty of a misdemeanor and punishable as set forth in § 1-7 of this code.  Tempe may also enforce this article pursuant to A.R.S. § 9-461.03 or under its authority to abate nuisances.

 

         (c)     If attempts to abate the violation are unsuccessful, the floodplain administrator shall submit to the administrator of Federal Insurance Administration a declaration for denial of insurance, stating that the property is in violation of a cited state or local law, regulation or ordinance, pursuant to § 1316 of the National Flood Insurance Act of 1968, as amended.

(Ord. No. 87.25, 9-10-87)

 

Sec. 12-26.  Severability.

 

         The ordinance from which this article is derived, and the various parts thereof, are hereby declared to be severable.  Should any section of this article be declared by the courts to be unconstitutional or invalid, such decision shall not affect the validity of the article as a whole or any portion thereof other than the section so declared to be unconstitutional or invalid.

(Ord. No. 87.25, 9-10-87)

 


Sec. 12-27.  Establishment of floodplain permit.

 

         A floodplain permit shall be obtained before construction or development begins within any special flood hazard area.  Application for a floodplain permit shall be made on forms furnished by the floodplain administrator and may include, but not be limited to, plans, in duplicate, drawn to scale, showing the nature, location, dimensions and elevation of the area in question; existing or proposed structures, fill, storage of materials, drainage facilities; and the location of the foregoing. Specifically, the following information is required:

 

         (1)     Proposed elevation, in relation to mean sea level, of the lowest floor (including basement) of all structures; in Zone AO, elevation of existing grade and proposed elevation of lowest floor of all structures;

 

         (2)     Proposed elevation, in relation to mean sea level, to which any structure will be floodproofed;

 

         (3)     Certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet the floodproofing criteria in § 12-29(c); and

 

         (4)     Description of the extent to which any watercourse will be altered or relocated as a result of proposed development.

(Ord. No. 87.25, 9-10-87; Ord. 2005.67, 9-29-05)

 

Sec. 12-28.  Designation, duties and responsibilities of the floodplain administrator.

 

         (a)     Designation.  The floodplain administrator is hereby designated as enforcing officer for this article and is hereby authorized and directed to formulate the procedures and criteria necessary to carry out its intent.  He may adopt a fee schedule for review of applications for permits and variances from the requirements of this article.

 

         (b)     Duties and responsibilities.  Duties of the floodplain administrator or his designee shall include, but not be limited to:

 

                  (1)     Review all floodplain permits to determine that:

 

                           a.      The permit requirements of this article have been satisfied;

 

                           b.      All other required state and federal permits relating to floodplains and  floodways have been obtained;

 

                           c.      The site is reasonably safe from flooding; and

 

                           d.      The proposed development does not adversely affect the carrying capacity of the floodway.  For purposes of this article, "adversely affects" means that the cumulative effect of the proposed development, when combined with all other existing and anticipated development within Tempe, will not increase the water surface elevation of the base flood more than one foot at any point.


                  (2)     Use of other base flood data.  When base flood elevation data has not been provided in accordance with § 12-20, the floodplain administrator shall obtain, review and reasonably utilize any base flood elevation data available from a federal, state or other source in order to administer this article.  Any such information shall be submitted to the floodplain board for adoption.

 

                  (3)     Obtain and maintain for public inspection and make available as needed for flood insurance policies:

 

                           a.      The certified elevation required in § 12-29(c)(1);

 

                           b.      The certification required in § 12-29(c)(2);

 

                           c.      The floodproofing certification required in § 12-29(c)(3); and

 

                           d.      The certified elevation required in § 12-32(b).

 

                  (4)     Whenever a watercourse is to be altered or relocated:

 

                           a.      Notify adjacent communities and the Arizona Department of Water Resources prior to such alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Insurance Administration; and

        

                           b.      Require that the flood-carrying capacity of the altered or relocated portion of said watercourse is maintained.

 

                  (5)     Within one hundred twenty (120) days after completion of construction of any flood control protective works which change the rate of flow during the flood or the configuration of the floodplain upstream or downstream from or adjacent to the project, the person or agency responsible for installation of the project shall provide to the governing bodies of all jurisdictions affected by the project a new delineation of all floodplains affected by the project.  The new delineation shall be done according to the criteria adopted by the Director of the Department of Water Resources of the State of Arizona.

 

                  (6)     Base flood elevations may increase or decrease resulting from physical changes affecting flooding conditions.  As soon as practicable, but not later than six (6) months after the date such information becomes available, the city floodplain administrator shall notify FEMA of the changes by submitting technical or scientific data in accordance with volume 44 of the Code of Federal Regulations, § 65.3.  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.

 


                  (7)     Advise the Flood Control District of Maricopa County and any adjunct jurisdiction having responsibility for floodplain management in writing and provide a copy of the development plans included with all applications for floodplain use permits to develop land in a floodplain or floodway within one mile of the corporate limits of the city.  Also, advise the Flood Control District of Maricopa County 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 within the district's area of jurisdiction.  Written notice and a copy of the plan of development shall be sent to the district no later than three (3) working days after having been received by the floodplain administrator.

 

                  (8)     Make interpretations where needed as to the exact location of the boundaries of special flood hazard areas (for example, where there appears to be a conflict between a mapped boundary and actual field conditions).  The person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation as provided in § 12-35.

 

                  (9)     Take actions on violations of this article as required in § 12-25 herein.

(Ord. No. 87.25, 9-10-87; Ord. 2005.67, 9-29-05)

 

Sec. 12-29.  Standards of construction.