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15.40.750 Elevation and wet floodproofing requirements.
   A.   Residential construction, new or substantial improvement, shall have the lowest floor, including basement:
   1.   In an AO Zone, elevated to or above the regulatory flood elevation, or elevated at least two feet above the highest adjacent grade if no depth number is specified;
   2.   In an A Zone where a base flood elevation has not been determined, elevated to or above the regulatory flood elevation, or elevated in accordance with the criteria developed either by FEMA or the Director of the Arizona Department of Water Resources;
   3.   In Zone AE, elevated to or above the regulatory flood elevation.
   B.   Upon completion of the structure and prior to occupancy, an elevation certificate indicating the elevation of the lowest floor, including basement, shall be certified by a registered, professional engineer or surveyor. The elevation certificate shall be provided to the floodplain administrator.
   C.    All new construction and substantial improvements with fully enclosed areas below the lowest floor that are subject to flooding (excluding basements) and areas that are usable solely for parking of vehicles, building access or storage, 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 be certified by a registered, professional engineer or architect to meet or exceed the following minimum criteria:
   1.   A minimum of two openings, on differing sides of each area, 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;
   2.   The bottom of an openings shall be no higher than one foot above grade;
   3.   Openings may be equipped with screens, louvers, valves, or other coverings or devices, provided that they permit the automatic entry and exit of floodwaters.
   If it is not feasible or desirable to meet the openings criteria stated above, alternatively a registered, engineer or architect may design and certify the openings.
   D.    Manufactured homes shall meet the standards of Section 15.40.760.
   E.   Garages and accessory storage buildings shall meet or exceed the following minimum criteria:
   1.   A garage attached to a residential structure, constructed with the garage floor slab below the regulatory flood elevation, must be designed to allow for the automatic entry of floodwaters as set forth in subsection 15.40.750.C. Areas of the garage below the regulatory flood elevation must be constructed with flood-resistant materials.
   2.   A garage attached to a nonresidential structure must meet the above requirements or be dry floodproofed.
   3.   A low-cost and small accessory structure used solely for parking and/or storage may be constructed such that its floor is below the regulatory flood elevation, provided the structure is designed and constructed in accordance with the following requirements:
      a.   Use of the accessory structure must be limited to parking or limited storage;
      b.   The portions of the accessory structure located below the regulatory flood elevation must be built using flood-resistant materials;
      c.   The accessory structure must be adequately anchored to prevent flotation, collapse and lateral movement;
      d.   Any mechanical and utility equipment in the accessory structure must be elevated or floodproofed to or above the regulatory flood elevation;
      e.   The accessory structure must comply with floodway encroachment provisions in Article V.
(Ord. 1397.15.22 § 1 (part), 2019; Ord. 1397.15.21 § 1 (part), 2007; prior code § 17-5-1.3)
15.40.760 Manufactured homes and home parks.
   A.   The new installation of a manufactured home within a floodway is prohibited.
   B.   A manufactured home and additions installed in a new location or as a replacement for an existing manufactured home in a special flood hazard area must be done in the following manner:
   1.   The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength, and is securely anchored to an adequately anchored foundation system to resist floatation, collapse, and lateral movement.
   2.   All manufactured homes shall be placed on pads or lots elevated on compacted fill, pilings, piers, stem walls or similar approved foundation design so that the bottom of the structural frame, or the lowest point of any attached appliances, whichever is lower, is to or above the regulatory flood elevation. If elevated:
      a.   The lots shall be large enough to permit steps;
      b.   The pilings shall be placed in a stable soil no more than ten feet apart; and
      c.   Reinforcement shall be provided for pilings more than six feet above ground level.
   C.   Upon completion of installation of the structure, the elevation of the lowest structural member or lowest point of any attached appliances, whichever is lower, shall be certified by a registered, professional engineer or surveyor, and verified by the community’s building inspector to be properly elevated. The certification and verification shall be provided to the floodplain administrator.
(Ord. 1397.15.22 § 1 (part), 2019; prior code § 17-4-1(H) (part))
15.40.770 Minimizing the potential for flood damage.
   Within any area of the city where the floodplain administrator determines that the land is subject to flooding, including but not limited to the special flood hazard areas, all development, including substantial improvements to structures, must meet the following requirements:
   A.   All new and substantially improved structures shall be anchored at their foundations to prevent flotation, collapse or lateral movement resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;
   B.   All new and substantially improved building construction materials and utility system equipment shall be resistant to flood damage. 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 their components during conditions of flooding;
   C.   The construction methods and practices shall be those which minimize flood damage;
   D.    Multiple occupancy developments, such as subdivisions, shopping centers, etc., shall have their public utility systems, such as sewer, water, gas and electric lines, and their associated facilities, located and constructed in a manner to minimize or eliminate the potential for flood damage. The developments must be constructed with drainage systems which will minimize the exposure to flood damage;
   E.   New and replacement water supply and sanitary sewage systems shall be designed and constructed to minimize or eliminate infiltration of floodwaters into the systems and the discharge from sanitary sewage systems into the floodwaters;
   F.   Onsite waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding;
   G.   Waste disposal systems shall not be installed wholly or partially in a floodway;
   H.   Adequate drainage paths shall be constructed around structures on slopes to guide floodwaters around and away from proposed structures.
   I.   The city may approve certain development in Zone AE on the city’s FIRM which increase the water surface elevation of the base flood by more than one foot, provided that the city first applies for a conditional FIRM revision, fulfills the requirements for such a revision as established under the provisions of 44 C.F.R. § 65.12, and receives the approval of the Federal Insurance Administrator.
   J.   Notwithstanding any other provisions of 44 C.F.R. § 60.3, a city may permit encroachments within the adopted regulatory floodway that would result in an increase in base flood elevations, provided that the city first applies for a conditional FIRM and floodway revision, fulfills the requirements for such revisions as established under the provisions of 44 C.F.R. § 65.12, and receives the approval of the Federal Insurance Administrator.
(Ord. 1397.15.22 § 1 (part), 2019; prior code § 17-4-1(L))
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