A. General Standards: In all special flood hazard areas the following provisions are required:
1. All new construction, substantial improvements, and development, including manufactured homes and accessory buildings, shall be designed (or modified) and adequately anchored to prevent flotation, collapse, and lateral movement of the structure, all new construction and substantial improvements shall be designed with engineered foundations and all development shall be reasonably safe from flooding.
2. All new construction, substantial improvements, and development shall be constructed with materials and utility equipment resistant to flood damage in accordance with the Technical Bulletin 2, Flood Damage-Resistant Materials Requirements, and available from the Federal Emergency Management Agency.
3. All new construction, substantial improvements, and development shall be constructed by methods and practices that minimize flood damages.
4. All new and replacement electrical, heating, ventilation, plumbing, 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 to the flood protection elevation, except as provided for in subsections A7 and B4, "Additions/Improvements", of this section. These include, but are not limited to, HVAC equipment, water softener units, bath/kitchen fixtures, ductwork, electric/gas meter panels/boxes, utility/cable boxes, hot water heaters, and electric outlets/switches.
5. Any proposed water supply and sanitation system shall prevent disease, contamination and unsanitary conditions as follows:
a. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.
b. All new and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters.
c. On-site waste disposal systems shall be located and constructed to avoid impairment to them or contamination from them during flooding.
6. A fully enclosed area, of new construction and substantially improved structures, which is below the lowest floor shall:
a. Be constructed entirely of flood resistant materials at least to the flood protection elevation; and
b. Include, in Zones A, AE, AH, AO, and A1-30, flood openings to automatically equalize hydrostatic flood forces on walls by allowing for the entry and exit of floodwaters. To meet this requirement, the openings must either be certified by a professional engineer or architect or meet or exceed the following minimum design criteria:
(1) A minimum of two (2) flood openings on different sides of each enclosed area subject to flooding;
(2) The total net area of all flood openings must be at least one square inch for each square foot of enclosed area subject to flooding or per engineered flood opening requirements;
(3) If a building has more than one enclosed area, each enclosed area must have flood openings to allow floodwaters to automatically enter and exit;
(4) The bottom of all required flood openings shall be no higher than one foot (1') above the interior or exterior adjacent grade, but only the net area of the flood opening below the base flood elevation may contribute to the required opening size;
(5) Flood openings may be equipped with screens, louvers, or other coverings or devices, provided they permit the automatic flow of floodwaters in both directions; and
(6) Enclosures made of flexible skirting are not considered enclosures for regulatory purposes, and, therefore, do not require flood openings. Masonry or wood underpinning, regardless of structural status, is considered an enclosure and requires flood openings as outlined above.
7. Nothing in this article shall prevent the repair, reconstruction, or replacement of a building or structure existing on the effective date of this article and located totally or partially within the floodway, flood fringe area, or stream setback, provided there is no additional encroachment below the flood protection elevation in the floodway, flood fringe area, or stream setback, and provided that such repair, reconstruction, or replacement meets all of the other requirements of this article.
8. New solid waste disposal facilities and sites, hazardous waste management facilities, salvage yards, and chemical storage facilities shall not be permitted in the special flood hazard area, except by variance as specified in subsection 17.04J.050E9 of this article. A structure or tank for chemical or fuel storage incidental to an allowed use or to the operation of a water treatment plant or wastewater treatment facility may be located in a special flood hazard area only if the structure or tank is either elevated or floodproofed to at least the flood protection elevation and certified in accordance with the provisions of subsection 17.04J.050C3, "Certification Requirements", of this article.
9. The proposed development shall cause no significant danger to life and property due to increased flood heights or velocities, no materials may be swept onto other lands or downstream to the injury of others and the proposed development shall be reasonably safe from flooding.
10. The proposed location shall represent the safest location on the subject property for the proposed use.
11. Safe access to the property shall be available in times of a base flood for ordinary and emergency vehicles.
12. Inherent natural characteristics of the watercourses shall be preserved.
13. Existing riparian vegetation and wildlife habitat along the stream bank and within the required one hundred foot (100') riparian setback shall be preserved.
14. New landscaping shall include plantings that are low growing and have dense root systems to stabilize stream banks and to repair any damage previously done to riparian vegetation.
15. Any chemicals or other toxic materials that could cause contamination of surface waters or groundwater, or that could be injurious to public health, safety and welfare, shall be located at the flood protection elevation and stored in a manner that prevents their release in the event of a flood.
16. When a structure is partially located in a special flood hazard area, the entire structure shall meet the requirements for new construction and substantial improvements.
17. When a structure is located in multiple flood hazard zones or in a flood hazard risk zone with multiple base flood elevations, the provisions for the more restrictive flood hazard risk zone and the highest base flood elevation (BFE) shall apply.
18. Fill is prohibited in the SFHA, including construction of buildings on fill, unless compensatory storage is provided so that the total amount of fill placed on the site does not exceed the amount excavated from the site. Placement of fill necessary to satisfy drainage requirements of the Building Code shall be allowed if determined necessary by the Floodplain Administrator. However, any placement of fill must be evaluated by the Floodplain Administrator to ensure that it does not have adverse impact on neighboring properties. This includes not giving City of Hailey approval when asked by FEMA to review Conditional Letters or Letters of Map Revision (CLOMR-F or LOMR-F), unless they meet the above requirements.
B. Specific Standards: In all special flood hazard areas where base flood elevation (BFE) data has been provided, as set forth in subsection 17.04J.030B, "Basis For Special Flood Hazard Areas", of this article, or subsection D, "Standards For Riverine Floodplains With Base Flood Elevations But Without Established Floodways Or Flood Fringe Areas", of this section, the following provisions, in addition to the provisions of subsection A, "General Standards", of this section, are required:
1. Residential Construction: New construction and substantial improvements shall have the top of the lowest floor, including basement, elevated no lower than the flood protection elevation, as defined in section 17.04J.020, "Definitions", of this article.
2. Non-Residential Construction: New construction and substantial improvements, of any commercial, industrial, or other non- residential structure shall have the top of the lowest floor, including basement, elevated no lower than the flood protection elevation, as defined in section 17.04J.020, "Definitions", of this article. Structures located in Zones A, AE, AH, AO, and A1-30 may be floodproofed to the flood protection elevation in lieu of elevation provided that all areas of the structure, together with attendant utility and sanitary facilities, below the flood protection elevation are watertight with walls substantially impermeable to the passage of water, using structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. For AH and AO Zones, the floodproofing elevation shall be in accordance with subsection F2 of this section. A registered professional engineer or architect shall certify that the floodproofing standards of this subsection are satisfied. Such certification shall be provided to the Floodplain Administrator as set forth in subsection 17.04J.050C3, "Certification Requirements", of this article along with the operational plan and the inspection and maintenance plan.
3. Manufactured Homes: This subsection applies to placement of all new manufactured homes in the jurisdiction.
a. New and replacement manufactured homes shall be elevated so that the lowest floor of the manufactured home is no lower than the flood protection elevation, as defined in section 17.04J.020, "Definitions", of this article.
b. Manufactured homes shall be securely anchored to an adequately anchored foundation to resist flotation, collapse, and lateral movement, by a certified engineered foundation system.
c. All enclosures or skirting below the lowest floor shall meet the requirements of subsection A6 of this section.
d. An evacuation plan must be developed for evacuation of all residents of all new, substantially improved, or substantially damaged manufactured home parks or subdivisions located within flood prone areas. This plan shall be filed with and approved by the Floodplain Administrator and the local Emergency Management Coordinator.
4. Additions/Improvements:
a. Additions and/or improvements to pre-FIRM structures when the addition and/or improvements in combination with any interior modifications to the existing structure are:
(1) Not a substantial improvement - the addition and/or improvements must be designed to minimize flood damages and must not be any more non-conforming than the existing structure; or
(2) A substantial improvement - both the existing structure and the addition and/or improvements must comply with the standards for new construction.
b. Additions to post-FIRM structures that are a substantial improvement with no modifications to the existing structure other than a standard door in the common wall shall require only the addition to comply with the standards for new construction.
c. Additions and/or improvements to post-FIRM structures when the addition and/or improvements in combination with any interior modifications to the existing structure are:
(1) Not a substantial improvement - the addition and/or improvements only must comply with the standards for new construction; or
(2) A substantial improvement - both the existing structure and the addition and/or improvements must comply with the standards for new construction.
d. Repairs to post-FIRM structures when the repairs in combination with any additions/improvements to the existing structure are:
(1) Not a substantial improvement - the repairs only must comply with the standards for new construction in place at the time of original construction; or
(2) A substantial improvement - both the repairs to the existing structure and the addition and/or improvements must comply with the standards for new construction.
e. Any combination of repair, reconstruction, rehabilitation, addition, or improvement of a building or structure taking place during a one year period, the cumulative cost of which equals or exceeds fifty percent (50%) of the market value of the structure before the improvement or repair is started, must comply with the standards for new construction. For each building or structure, the one year period begins on the date of the first improvement or repair of that building or structure subsequent to the effective date of this article. If the structure has sustained substantial damage, any repairs are considered substantial improvement regardless of the actual repair work performed. The requirement does not, however, include either:
(1) Any project for improvement of a building required to correct existing Health, Sanitary, or Safety Code violations identified by the building official and that are the minimum necessary to assume 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.
5. Recreational Vehicles: Recreational vehicles shall be either:
a. Temporary Placement:
(1) Be on site for fewer than one hundred eighty (180) consecutive days and be fully licensed and ready for highway use (a recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick disconnect type utilities, and has no permanently attached additions); or
b. Permanent Placement:
(1) Recreational vehicles that do not meet the limitations of temporary placement shall meet all the requirements for new construction, as set forth in subsection A, "General Standards", of this section.
6. Temporary Non-Residential Structures: Prior to the issuance of a floodplain development permit for a temporary structure, the applicant must submit to the Floodplain Administrator a plan for the removal of such structure(s) in the event of a flash flood or other type of flood warning notification. The following information shall be submitted in writing to the Floodplain Administrator for review and written approval:
a. A specified time period for which the temporary use will be permitted. Time specified may not exceed six (6) months, renewable up to one year;
b. The name, address, and phone number of the individual responsible for the removal of the temporary structure;
c. The time frame prior to the event at which a structure will be removed (i.e., immediately upon flood warning notification);
d. A copy of the contract or other suitable instrument with the entity responsible for physical removal of the structure; and
e. Designation, accompanied by documentation, of a location outside the special flood hazard area, to which the temporary structure will be moved.
7. Accessory Structures That Do Not Include Living Space: When such accessory structures (sheds, detached garages, etc.) are to be placed within a special flood hazard area, elevation or floodproofing certifications are required for all accessory structures in accordance with subsection 17.04J.050C3, "Certification Requirements", of this article, and the following criteria shall be met:
a. Accessory structure shall not be used for human habitation (including working, sleeping, living, cooking, or restroom areas);
b. Accessory structure shall be designed to have low flood damage potential;
c. Accessory structure shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters;
d. Accessory structure shall be firmly anchored in accordance with the provisions of subsection A1 of this section;
e. All service facilities, such as electrical, shall be installed in accordance with the provisions of subsection A4 of this section; and
f. Flood openings to facilitate automatic equalization of hydrostatic flood forces shall be provided below flood protection elevation in conformance with the provisions of subsection A6b of this section.
If said accessory structure has a footprint less than two hundred (200) square feet and satisfies the criteria outlined in subsections B7a through B7f of this section, it is not required to meet the elevation or floodproofing standards of subsection B2, "Non-Residential Construction", of this section.
8. Tanks: When gas and liquid storage tanks are to be placed within a special flood hazard area, the following criteria shall be met:
a. Underground tanks in flood hazard areas shall be anchored to prevent flotation, collapse, or lateral movement resulting from hydrodynamic and hydrostatic loads during conditions of the base flood, including the effects of buoyancy (assuming the tank is empty);
b. Elevated above-ground tanks, in flood hazard areas shall be attached to and elevated to or above the flood protection elevation on a supporting structure that is designed to prevent flotation, collapse, or lateral movement during conditions of the base flood. Tank-supporting structures shall meet the foundation requirements of the applicable flood hazard area;
c. Not elevated above-ground tanks, that do not meet the elevation requirements of subsection B2 of this section shall be permitted in flood hazard areas provided the tanks are anchored or otherwise designed and constructed to prevent flotation, collapse or lateral movement resulting from hydrodynamic and hydrostatic loads during conditions of the design flood, including the effects of buoyancy assuming the tank is empty and the effects of flood-borne debris.
d. Tank inlets, fill openings, outlets and vents shall be:
(1) At or above the flood protection elevation or fitted with covers designed to prevent the inflow of floodwater or outflow of the contents of the tanks during conditions of the base flood; and
(2) Anchored to prevent lateral movement resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy, during conditions of the base flood.
9. Construction Of Below-Grade Crawlspace: (See figures 1 and 2 of this section.)
a. The interior grade of a crawlspace must not be more than two feet (2') below the exterior lowest adjacent grade (LAG).
b. The height of the below-grade crawlspace, measured from the interior grade of the crawlspace to the top of the crawlspace foundation wall, must not exceed four feet (4') at any point.
c. There must be an adequate drainage system that removes floodwaters from the interior area of the crawlspace. The enclosed area should be drained within a reasonable time after a flood event.
d. The velocity of floodwaters at the site should not exceed five feet (5') per second for any crawlspace.
(See Technical Bulletin 11 for further information. Caution: Buildings that have below-grade crawlspaces will have higher flood insurance premiums than buildings that have the preferred crawlspace construction, with the interior elevation of the crawlspace soil at or above the base flood elevation (BFE).)
FIGURE 1
PREFERRED CRAWLSPACE
] FIGURE 2
BELOW-GRADE CRAWLSPACE
10. Other Development In The Flood Fringe:
a. Fences in the flood fringe that have the potential to block the passage of floodwaters, such as stockade fences and tightly- spaced wire mesh fences, shall be open below the base flood elevation to allow the free passage of floodwaters. Minimum two inch (2") mesh shall be allowed below the base flood elevation if necessary to prevent the passage of pets and children. Seasonal removal of fencing mesh is encouraged. Fences are prohibited in the floodway.
b. Floodplain development permit applications for fences shall be processed through the fence permit review process and shall be subject only to the fence permit application fee. All provisions of this article shall apply in addition to the provisions of chapter 17.08, article A, "Fences, Signs", of this title.
11. Subdivision Plats; Flood Zones: All subdivision proposals shall:
a. Be consistent with the need to minimize flood damage and determined to be reasonably safe from flooding.
b. Have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage.
c. Have adequate drainage provided to reduce exposure to flood hazards.
d. Minimize flood damage, to the extent possible, through design criteria, such as requiring building envelopes, minimizing the size of building envelopes, locating building envelopes in the safest locations, reducing the number and size of encroachments in the floodplain and providing unobstructed passage of floodwaters.
e. Include the mapped flood hazard zones from the effective FIRM shown on the preliminary plat.
f. Have received all necessary permits from those governmental agencies for which approval is required by Federal or State law, including section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 USC 1334.
g. Provide a note on the final plat documenting the current flood zone in which the property or properties are located. The boundary line must be drawn on the plat in situations where two (2) or more flood zones intersect over the property or properties being surveyed.
h. Include the following notes on each subdivision plat:
FEMA FIRM panel(s): #160xxxxxxC, & 160xxxxxxE, etc.
FIRM effective date(s): mm/dd/year
Flood Zone(s): Zone X, Zone A, Zone AE, A Zone AO, Zone, AH, Zone D, etc.
Base Flood Elevation(s): AE .0 ft., etc.
Flood Zones are subject to change by FEMA & all land within a floodway or floodplain is regulated by chapter/section of the City/County Code.
12. Critical Facilities: Critical facilities, where permitted, shall be constructed at a three foot (3') flood protection elevation (FPE).
C. Standards For Floodplains Without Established Base Flood Elevations: Within the special flood hazard areas designated as Zone A (also known as Unnumbered A Zones) and established in subsection 17.04J.030B, "Basis For Special Flood Hazard Areas", of this article, where no base flood elevation (BFE) data has been provided by FEMA, the following provisions, in addition to the provisions of subsection A, "General Standards", of this section shall apply:
The BFE used in determining the flood protection elevation (FPE) shall be determined based on the following criteria:
1. When base flood elevation (BFE) data is available from other sources, all new construction and substantial improvements within such areas shall also comply with all applicable provisions of this article and shall be elevated or floodproofed in accordance with standards in subsections A, "General Standards", and B, "Specific Standards", of this section.
2. When floodway or flood fringe data is available from a Federal, State, or other source, all new construction and substantial improvements within floodway and flood fringe areas shall also comply with the requirements of subsections B, "Specific Standards", and E, "Standards For Floodways", of this section as applicable.
3. All subdivision, manufactured home park, and other development proposals shall provide base flood elevation (BFE) data if development is greater than five (5) acres or has more than fifty (50) lots/manufactured home sites. Such base flood elevation (BFE) data shall be adopted by reference in accordance subsection 17.04J.030B, "Basis For Special Flood Hazard Areas", of this article and utilized in implementing this article. The applicant/developer shall submit an application for a Conditional Letter of Map Revision (CLOMR) prior to preliminary plat approval and have obtained a Letter of Map Revision (LOMR) prior to any building permits for structures being issued.
4. When base flood elevation (BFE) data is not available from a Federal, State, or other source as outlined above, the lowest floor shall be elevated or floodproofed (non-residential) to two feet (2.0') above the highest adjacent grade (HAG) at the building site or to the flood protection elevation (FPE) whichever is higher, as defined in section 17.04J.020, "Definitions", of this article. All other applicable provisions of subsection B, "Specific Standards", of this section shall also apply.
D. Standards For Riverine Floodplains With Base Flood Elevations But Without Established Floodways Or Flood Fringe Areas: Along rivers and streams where base flood elevation (BFE) data is provided by FEMA or is available from another source but neither floodway nor flood fringe areas are identified for a special flood hazard area on the FIRM or in the FIS report, the following requirements shall apply to all development within such areas:
1. Standards of subsections A, "General Standards", and B, "Specific Standards", of this section; and
2. Until a regulatory floodway or flood fringe area is designated, no encroachments, including fill, new construction, substantial improvements, or other development shall be permitted unless certification with supporting technical data by a registered professional engineer is provided demonstrating that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood at any point within the community.
E. Standards For Floodways: Areas designated as floodways are located within the special flood hazard areas established in subsection 17.04J.030B, "Basis For Special Flood Hazard Areas", of this article. The floodways areas are extremely hazardous areas due to the velocity of floodwaters that have erosion potential and carry debris and potential projectiles. The following provisions, in addition to standards outlined in subsections A, "General Standards", and B, "Specific Standards", of this section and section 17.04J.070, "City Issued Stream Alteration Permit", of this article shall apply to all development within such areas:
1. No encroachments, including fill, new construction, substantial improvements, and other developments shall be permitted unless:
a. It is demonstrated that the proposed encroachment would not result in any increase in the flood levels during the occurrence of the base flood, based on hydrologic and hydraulic analyses performed in accordance with standard engineering practice and presented to the Floodplain Administrator prior to issuance of floodplain development permit; or
b. A Conditional Letter of Map Revision (CLOMR) has been approved by FEMA. A Letter of Map Revision (LOMR) must also be obtained within six (6) months of completion of the proposed encroachment.
2. If subsection E1 of this section is satisfied, all development shall comply with all applicable flood hazard reduction provisions of this article.
F. Standards For Areas Of Shallow Flooding (Zone AO, AH, AR/AO, Or AR/AH): Located within the special flood hazard areas established in subsection 17.04J.030B, "Basis For Special Flood Hazard Areas", of this article are areas designated as shallow flooding areas. These areas have special flood hazards associated with base flood depths of one foot (1') to three feet (3') where a clearly defined channel does not exist and where the path of flooding is unpredictable and indeterminate. In addition to subsections A, "General Standards", and B, "Specific Standards", of this section all new construction and substantial improvements shall meet the following requirements:
1. The lowest floor shall be elevated at least as high as the depth number specified on the Flood Insurance Rate Map (FIRM), in feet, plus a freeboard of two feet (2'), above the highest adjacent grade; or at least four feet (4') above the highest adjacent grade if no depth number is specified.
2. Non-residential structures may, in lieu of elevation, be floodproofed to the same level as required in subsection F1 of this section so that the structure, together with attendant utility and sanitary facilities, below that level shall be watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. Certification is required in accordance with subsection 17.04J.050C3, "Certification Requirements", of this article and subsection B2, "Non-Residential Construction", of this section.
3. Adequate drainage paths shall be provided around structures on slopes to guide floodwaters around and away from proposed structures.
G. Standards For Areas Where Floodway Has Not Been Determined: Where the floodway has not been determined, no new construction, substantial improvements or other development (including fill) shall be permitted in Zone AE on the effective FIRM, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood at any point within the community. Certification and documentation by a licensed professional engineer shall be submitted to demonstrate compliance with this subsection.
1. Applicants of proposed projects that increase the base flood are required to obtain and submit to the Floodplain Administrator, a Conditional Letter of Map Revision (CLOMR) preconstruction.
2. Postconstruction, the applicant must apply to FEMA for a Letter of Map Revision for changes to the flood hazard map proposed in the CLOMR.
H. Conditions Of Approval: Upon consideration of the criteria in subsections A through G of this section, the Floodplain Administrator, the commission or the Council, as the case may be, may attach such conditions to the permit, as deemed necessary to further the purposes of this district, including, but not limited to:
1. Modification of water disposal and water supply facilities to minimize or eliminate infiltration of floodwaters.
2. Limitations of periods of use and operation.
3. Imposition of operational controls, sureties and deed restrictions.
4. Requirements or prohibition of construction of channel modification dikes, levees and other protective measures.
5. Submission of a plan or document certified by a registered professional engineer/architect stating that the floodproofing measures comply with this article.
6. Floodproofing measures for structures, such as the following:
a. Installation of watertight doors, bulkheads, shutters and similar structures.
b. Reinforcement of walls to resist water pressures.
c. Use of paints, membrane or mortars to reduce seepage of water through walls.
d. Addition of mass or weight to structures to resist flotation.
e. Installation of pumps to lower water levels in structures.
f. Construction of water supply and waste treatment systems so as to prevent the entrance of floodwaters.
g. Installation of pumping facilities or comparable subsurface drainage systems for buildings to relieve external foundation wall flood pressures.
h. Construction to resist rupture or collapse caused by water pressure or floating debris.
i. Installation of valves or controls on sanitary and storm drains that will permit the drains to be closed to prevent backup of sewage and stormwaters into the building or structures.
j. Location of all electrical equipment, circuits and installed electrical appliances in a manner which will assure they are not subject to flooding and to provide protection from inundation by the floodwaters.
k. Location of any structural storage facilities for chemicals, explosives, buoyant materials, flammable liquids, or other toxic materials which could be hazardous to public health, safety and welfare in a manner which will assure that the facilities are situated at least to the flood protection elevation and/or are adequately floodproofed to prevent flotation of storage containers, or damage to storage containers which could result in the escape of toxic materials into floodwaters.
7. Location of building pads or envelopes.
8. Installation and maintenance of new landscaping and preservation of existing riparian vegetation.
9. Obtain all required and necessary Federal and State permits (e.g., 404 permits, Endangered Species Act consultation, etc.).
10. Any other condition reasonably related to the issuance of a floodplain development permit. (Ord. 1234, 2018)