10-1-8-1: APPLICABILITY:

   A.   The requirements of subsection 10-1-8-7C5 of this chapter, regarding the floodway setback in effect at the time of receipt by the city of a preliminary plat application shall apply for subsequent development of those lots.

   B.   All other provisions of this section 10-1-8 shall apply to any development application received subsequent to the effective date. (Ord. 700A, 3-11-2014; amd. Ord. 815, 7-23-2019)

10-1-8-2: GENERAL BUILDING REQUIREMENTS:

   A.   Review Of Building Permits: Where elevation data is not available, either through the flood insurance study or from another authoritative source, applications for building permits shall be reviewed to assure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, and any other relevant factors, where applicable. Failure to elevate at least two feet (2') above grade in these zones may result in higher insurance rates.

   B.   Construction Materials And Methods: All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage and using methods and practices that minimize flood damage in accordance with the Technical Bulletin 2, “Flood Damage-Resistant Materials Requirements”, and available from the Federal Emergency Management Agency or in conformance with this chapter, whichever is more stringent.

   C.   Design, Location Of Certain Equipment: Electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities, shall be located at a minimum of the flood protection level, as defined in section 10-1-5, so as to prevent water from entering or accumulating within the components during conditions of flooding. On-site waste disposal systems shall be located and constructed to avoid functional impairment, or contamination from them, during flooding.

   D.   All new construction and substantial improvements shall be constructed by methods and practices that minimize flood damages.

   E.   Any alteration, repair, reconstruction, or improvements to a structure, which is in compliance with the provisions of this chapter, shall meet the requirements of "new construction" as defined in section 10-1-5.

   F.   Nothing in this chapter shall prevent the repair, reconstruction, or replacement of a building (within the original footprint) or structure existing on the effective date of this chapter 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 chapter, including, but not limited to, construction within the original building footprint and in conformance with the substantial improvement criteria.

   G.   New solid waste disposal facilities and sites, hazardous waste management facilities, salvage yards, and chemical storage facilities shall not be permitted, except by variance as specified in section 10-1-10. 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 section 10-1-8-2K.

   H.   When a structure is partially located within an area of special flood hazard, the entire structure shall meet the requirements for new construction and substantial improvements.

   I.   When a structure is located within 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.

   J.   Certification Requirements:

      1.   Elevation Certificates:

         a.   An elevation certificate (FEMA Form 86-0-33) is required prior to the actual start of any new construction for all structures included within or removed from the special flood hazard area (SFHA). It shall be the duty of the permit holder to submit to the floodplain administrator a certification of the elevation of the lowest floor, in relation to mean sea level. The floodplain administrator shall review the certificate data submitted. Deficiencies detected by such review shall be corrected by the permit holder prior to the beginning of construction. Failure to submit the certification or failure to make required corrections shall be cause to deny a floodplain development permit.

         b.   The floodplain administrator may require an elevation certificate (FEMA Form 86-0-33) after the lowest floor is established. If required, within seven (7) calendar days of establishment of the lowest floor elevation, it shall be the duty of the permit holder to submit to the floodplain administrator a certification of the elevation of the lowest floor, in relation to mean sea level. Any work done within the seven (7) day calendar period and prior to submission of the certification shall be at the permit holder's risk. The floodplain administrator shall review the certificate data submitted. Deficiencies detected by such review shall be corrected by the permit holder immediately and prior to further work being permitted to proceed. Failure to submit the certification or failure to make required corrections shall be cause to issue a stop-work order for the project.

         c.   (1)   A final as-built finished construction elevation certificate (FEMA Form 86-0-33) is required for all structures included within or removed from the special flood hazard area (SFHA) after construction is completed and prior to certificate of occupancy issuance. It shall be the duty of the permit holder to submit to the floodplain administrator a certification of final as-built construction of the elevation of the lowest floor and all attendant utilities. The floodplain administrator shall review the certificate data submitted. Deficiencies detected by such review shall be corrected by the permit holder immediately and prior to certificate of occupancy issuance. In some instances, another certification may be required to certify corrected as-built construction. Failure to submit the certification or failure to make required corrections shall be cause to withhold the issuance of a certificate of occupancy.

            (2)   The finished construction elevation certificate certifier shall provide at least two (2) photographs showing the front and rear of the building taken within ninety (90) days from the date of certification. The photographs must be taken with views confirming the building description and diagram number provided in divison A. To the extent possible, these photographs should show the entire building including foundation. If the building has split-level or multi-level areas, provide at least two (2) additional photographs showing side views of the building. In addition, when applicable, provide a photograph of the foundation showing a representative example of the flood openings or vents. All photographs must be in color and measure at least three inches (3") by three inches (3"). Digital photographs are acceptable.

      2.   Floodproofing Certificate: If non-residential floodproofing is used to meet the flood protection elevation requirements, a floodproofing certificate (FEMA Form 086-0-34), with supporting data, an operational plan, and an inspection and maintenance plan are required prior to the actual start of any new construction. It shall be the duty of the permit holder to submit to the floodplain administrator a certification of the floodproofed design elevation of the lowest floor and all attendant utilities, in relation to mean sea level. Floodproofing certification shall be prepared by or under the direct supervision of a professional engineer or architect and certified by same. The floodplain administrator shall review the certificate data, the operational plan, and the inspection and maintenance plan. Deficiencies detected by such review shall be corrected by the applicant prior to permit approval. Failure to submit the certification or failure to make required corrections shall be cause to deny a floodplain development permit. Failure to construct in accordance with the certified design shall be cause to withhold the issuance of a certificate of compliance/occupancy.

      3.   If a manufactured home is placed within zone A, AE, AH, AO, or A1-30 and the elevation of the chassis is more than thirty six inches (36") in height above grade, an engineered foundation certification is required in accordance with the provisions of section 10-1-8-6C.

      4.   Certification Exemptions: The following structures, if located within zone A, AE, AH, AO, or A1-30, are exempt from the elevation/floodproofing certification requirements specified in this division:

         a.   Recreational vehicles meeting requirements of section 10-1-8-7D;

         b.   Temporary structures meeting requirements of section 10-1-8-6E;

         c.   Accessory structures less than two hundred (200) square feet meeting requirements of section 10-1-8-6F.

         d.   Approved letter of map revision based on fill (LOMR-F), reflecting the lowest lot elevation (LLE) to be a minimum of one and one half feet (1.5') of fill above base flood elevation.

(Ord. 332, 2-23-1999; amd. Ord. 700A, 3-11-2014; Ord. 815, 7-23-2019)

10-1-8-3: ANCHORING:

   A.   All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydraulic loads, including the effects of buoyancy.

   B.   All manufactured homes must likewise be anchored to prevent flotation, collapse or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over the top or frame ties to ground anchors (reference FEMA's "Manufactured Home Installation In Flood Hazard Areas" guidebook for additional techniques).

(Ord. 700A, 3-11-2014; amd. Ord. 815, 7-23-2019)

10-1-8-4: WATER AND SEWER SYSTEMS:

   A.   All new and replacement water supply systems and sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems; and discharge from the systems into floodwaters.

   B.   On site waste disposal systems shall be located to avoid impairment of them or contamination from them during flooding; and

   C.   All sewer and water systems shall be approved by the district health department or the Idaho department of environmental quality.

(Ord. 332, 2-23-1999; amd. Ord. 700A, 3-11-2014; Ord. 815, 7-23-2019)

10-1-8-5: SUBDIVISIONS 1 :

   A.   All subdivision proposals shall be consistent with the need to minimize flood damage;

   B.   All subdivision proposals and other development proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage;

   C.   All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage; and

   D.   Base flood elevation data shall be provided for subdivision proposals and other proposed development located within any area of special flood hazard.

   E.   All subdivision plats shall identify and designate the 100-year floodplain boundary and the floodway boundary including a certification by a registered surveyor that the boundaries were established consistent with the FIRM map (in effect at the time of approval of the plat) for the city of Eagle. All subdivision plats shall contain a note or notes that warn prospective buyers of property that sheet flooding can and will occur and that floods of greater magnitude may inundate areas outside identified floodway and floodplain boundary lines.

   F.   All subdivision plats shall contain note(s) that refer to the required twenty five foot (25') setback from all waterways, called the riparian zone, in which no improvement is permitted and require that riparian vegetation shall be maintained in its natural state for the protection and stabilization of the riverbank and that removal of trees or other vegetation is regulated.

   G.   All subdivision proposals and other development proposals shall have received all necessary permits from those governmental agencies for which approval is required by federal or state statute, including section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 USC § 1334.

(Ord. 332, 2-23-1999; amd. Ord. 485, 7-24-2007; amd. Ord. 700A, 3-11-2014; Ord. 815, 7-23-2019)

 

Notes

1	1. See also title 9 of this code.

10-1-8-6: SPECIFIC STANDARDS:

In all cases of special flood hazards where base flood elevation (BFE) data has been provided as set forth in section 10-1-6 of this chapter, the provisions of this section shall be required:

   A.   Residential Construction:

      1.   Connection to a central sewage treatment system shall be required. This requirement may be waived by the city council if the Central district health department recommends approval of an alternate method of sewage treatment and disposal. Residential development within the floodplain may be clustered (through approval of a PUD) to facilitate the economics of the sewage infrastructure.

      2.   New construction and substantial improvement of any residential structure (including manufactured homes) shall have a finish floor elevated no lower than the flood protection elevation, as defined in section 10-1-5, and the lowest floor, including basement and crawl space, shall be elevated to a minimum of one foot (1') above the base flood elevation.

      3.   Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or 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.   A minimum of two (2) openings on different sides 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.

         b.   The total net area of all flood openings must be at least one (1) square inch for each square foot of enclosed area subject to flooding.

         c.   If a building has more than one (1) enclosed area, each enclosed area must have flood openings to allow floodwaters to automatically enter and exit.

         d.   The bottom of all required flood openings shall be no higher than one foot (1') above the interior or exterior adjacent grade.

         e.   Flood openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.

         f.   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.

      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.   Any combination of repair, reconstruction, rehabilitation, addition, or improvement of a building or structure taking place during a ten (10) year period, the cumulative cost of which equals or exceeds forty percent (40%) 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 ten (10) year period begins on the date of the first improvement or repair of that building or structure subsequent to the effective date of this chapter. 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.

   B.   Nonresidential Construction: New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor elevated to no lower than the flood protection elevation, as defined in section 10-1-5; or together with attendant utility and sanitary facilities, shall:

      1.    Be floodproofed to a point two feet (2') above the base flood elevation so that the structure is watertight with walls substantially impermeable to the passage of water;

      2.   Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and

      3.   Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this subsection based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the official as set forth in subsection 10-1-9B of this chapter.

      4.   Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in subsection A of this section.

      5.   Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot (1') below the floodproofed level (e.g., a building constructed to the base flood level will be rated as 1 foot below that level).

   C.   Manufactured Homes:

      1.   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 10-1-5.

      2.   Manufactured homes shall be securely anchored to an adequately anchored foundation to resist flotation, collapse, and lateral movement, either by certified engineered foundation system, or in accordance with the most current edition of the Idaho division of building safety's "Idaho Manufactured Home Installation Standard" in accordance with Idaho Code, section 44-2201(2). Additionally, when the elevation would be met by an elevation of the chassis thirty six (36) inches or less above the grade at the site, the chassis shall be supported by reinforced piers or engineered foundation. When the elevation of the chassis is above thirty six (36) inches in height, an engineering certification is required.

      3.   All enclosures or skirting below the lowest floor shall meet the requirements of section 10-1-8-6A3.

      4.   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.

   D.   Recreational Vehicles: Recreational vehicles shall be either: In all areas of special flood hazard (ASFH), recreational vehicles must be either:

      1.   Temporary Placement: 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

      2.   Permanent Placement: Recreational vehicles that do not meet the limitations of temporary placement shall meet all the requirements for new construction, as set forth in section 10-1-8-2.

   E.   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:

      1.   A specified time period for which the temporary use will be permitted. Time specified may not exceed six (6) months, renewable up to one (1) year;

      2.   The name, address, and phone number of the individual responsible for the removal of the temporary structure;

      3.   The time frame prior to the event at which a structure will be removed (for example, immediately upon flood warning notification);

      4.   A copy of the contract or other suitable instrument with the entity responsible for physical removal of the structure; and

      5.   Designation, accompanied by documentation, of a location outside the special flood hazard area, to which the temporary structure will be moved.

   F.   Accessory Structures: When accessory structures (sheds, detached garages, and the like) are to be placed within a special flood hazard area, elevation or floodproofing certifications are required for all accessory structures (except as exempted below) in accordance with section 10-1-8-2B and/or J2 and the following criteria shall be met:

      1.   Accessory structures shall not be used for human habitation (including working, sleeping, living, cooking, or restroom areas);

      2.   Accessory structures shall not be temperature-controlled;

      3.   Accessory structures shall be designed to have low flood damage potential;

      4.   Accessory structures shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters;

      5.   Accessory structures shall be firmly anchored in accordance with the provisions of section 10-1-8-3 of this chapter;

      6.   All service facilities, such as electrical, shall be installed in accordance with the provisions of section 10-1-8-2C of this chapter; and

      7.   Flood openings to facilitate automatic equalization of hydrostatic flood forces shall be provided below flood protection elevation in conformance with the provisions of section 10-1-8-6A3 of this chapter.

   An accessory structure with a footprint less than two hundred (200) square feet and is a minimal investment of three thousand dollars ($3,000.00) or less and satisfies the criteria outlined in divisions a. through g. above is not required to meet the certification requirements of elevation or floodproofing standards section 10-1-8-6B of this chapter.

   G.   Tanks: When gas and liquid storage tanks are to be placed within a special flood hazard area, the following criteria shall be met:

      1.   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);

      2.   Elevated above-ground tanks, in flood hazard areas shall be attached to and elevated to or above the design flood 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;

      3.   Not elevated above-ground tanks, that do not meet the elevation requirements of section 10-1-8-6B 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.

      4.   Tank inlets, fill openings, outlets and vents shall be:

         a.   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

         b.   Anchored to prevent lateral movement resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy, during conditions of the base flood.

   H.   Construction Of Below-Grade Crawlspace:

      1.   The interior grade of a crawlspace shall be one-foot (1') above the base flood elevation (BFE) and must not be more than two (2) feet below the exterior lowest adjacent grade (LAG).

      2.   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.

   I.   Other Development In Regulated Floodways:

      1.   Fences that have the potential to block the passage of floodwaters, such as stockade fences and wire mesh fences, in regulated floodways and flood fringe shall meet the limitations of section 10-1-8-7C.

      2.   Retaining walls, bulkheads, sidewalks, and driveways that involve the placement of fill in regulated floodways and flood fringe shall meet the limitations of section 10-1-8-7C.

      3.   Roads and watercourse crossings, including roads, bridges, culverts, low-water crossings, and similar means for vehicles or pedestrians to travel from one side of a watercourse to the other side, which encroach into regulated floodways and flood fringe, shall meet the limitations of section 10-1-8-7C.

      4.   Drilling water, oil, and/or gas wells including fuel storage tanks, apparatus, and any equipment at the site that encroach into regulated floodways and flood fringe shall meet the limitations of section 10-1-8-7C and M.

      5.   Docks, piers, boat ramps, marinas, moorings, decks, docking facilities, port facilities, shipbuilding, and ship repair facilities that encroach into regulated floodways and flood fringe shall meet the limitations of section 10-1-8-7C.

(Ord. 332, 2-23-1999; amd. Ord. 485, 7-24-2007; Ord. 700A, 3-11-2014; Ord. 815, 7-23-2019)

10-1-8-7: FLOODPLAIN AND FLOODWAY STANDARDS:

   A.   Standards For Floodplains Without Established Base Flood Elevations (BFE):

   Within the special flood hazard areas designated as zone A (also known as unnumbered A zones) and established in section 10-1-6, where no base flood elevation (BFE) data has been provided by FEMA, the following provisions, in addition to the provisions of section 10-1-8-2 and section 10-1-8-6, shall apply.

   The BFE used in determining the flood protection elevation (FPE) shall be 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 chapter and shall be elevated or floodproofed in accordance with standards in section 10-1-8-6.

      2.   When floodway data is available from a federal, state, or other source, all new construction and substantial improvements within floodway areas shall also comply with the requirements of sections 10-1-8-2 and 10-1-8-6.

      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 with section 10-1-6 and utilized in implementing this chapter. 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') above the highest adjacent grade (HAG) at the building site or to the flood protection elevation (FPE) whichever is higher, as defined in section 10-1-5. All other applicable provisions of section 10-1-8-6 shall also apply.

   B.   Standards For Rivervine Floodplains With Base Flood Elevations But Without Established Floodways:

Along rivers and streams where base flood elevations (BFE) data is provided by FEMA or is available from another source but floodway areas are not identified for a special flood hazard area on the FIRM or is in the FIS report, the following requirements shall apply to all development within such areas:

      1.   Standards of section 10-1-8-6.

      2.   Until a regulatory floodway or flood fringe area is designated, no encroachments, including fill, new construction, substantial improvements, or other developments 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.

   C.   Standards For Floodways And Flood Fringe Areas: Areas designated as floodways are located within special flood hazard areas established in section 10-1-6. The floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectile and erosion potential. The following provisions apply:

      1.   Encroachments, including fill, new construction, substantial improvements and other development, are prohibited unless an approved floodplain development permit is issued demonstrating that encroachments shall not result in any adverse impacts during the occurrence of the base flood.

      2.   Encroachments, including fill, new construction, substantial improvements and other development are prohibited unless certification by a registered professional hydraulic engineer is provided demonstrating that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge; and uses within the floodway shall be restricted to those which are required by public necessity (for example, bridges, water pumps); recreational use (for example, paths); wildlife habitat improvements (for example, vegetation, nesting structures, pool/riffle improvements); and gravel extraction; provided that the use/encroachment meets the approval of the federal emergency management agency and national flood insurance program and does not jeopardize the city's participation in the national flood insurance program.

      3.   Division C1 of this section shall comply with all applicable flood hazard reduction provisions of this section 10-1-8.

      4.   The placement of any mobile homes, as defined in section 8-1-2 of this code, is prohibited.

      5.   All buildings shall be set back a minimum of one hundred feet (100') from the floodway line. Except that when the special flood hazard area boundary is one hundred feet (100') or less from the floodway line, the boundary line shall be the setback line.

      6.   No development is permitted within the twenty five foot (25') setback from all waterways called the riparian zone and riparian vegetation shall be maintained in its natural state for the protection and stabilization of the riverbank, and removal of trees or other vegetation is regulated in accordance with this chapter.

      7.   For all subdivisions along the Boise River or Dry Creek, prior to approval of the final plat written approval from flood control district 10 is required to protect access to the river for maintenance.

      8.   Compensating excavation in accordance with an engineered plan for orderly conveyance of floodwater, or equivalent mitigating measures may be performed in the floodway when certified by a registered professional engineer. Mitigation design shall include provisions to prevent relocation or diversion of flow paths from causing increased jeopardy to any off site property at any level of flooding from the one (1) year flood up to the base flood. Maintenance provisions for excavated areas prone to fill from sediment and other debris shall follow the requirements of section 9-3-2-5C of this code for private streets.

      9.   In the design of public and private parks and open space areas, fixed structures or equipment that would impede floodwaters shall not be permitted within the floodway.

      10.   Any non-floodway area surrounded by the floodway shall be subject to the conditions of divisions C1 through C9 of this section, unless such area is accessed by at least one (1) road with suitable structures or culverts to pass floodwaters. If a bridge is required, it shall be elevated one foot (1') above the base flood elevation, have scour resistant footings extending to five feet (5') below the bottom of the channel and be capable of supporting an H-15 load as defined by the american association of state highway and transportation officials (AASHTO).

      11.   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.

   D.   Standards For Areas Of Shallow Flooding (Zone AO, AH, AR/AO, or AR/AH): Located within the special flood hazard areas established in section 10-1-6, are areas designated as shallow flooding areas. These areas have special flood hazards associated with base flood depths of one (1) to three (3) feet where a clearly defined channel does not exist and where the path of flooding is unpredictable and indeterminate. In addition to sections 10-1-8-2 and 10-1-8-6, 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 three feet (3') 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 section 10-1-8-7D1 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 sections 10-1-8-2K and 10-1-8-6B.

      3.   Adequate drainage paths shall be provided around structures on slopes to guide floodwaters around and away from proposed structures.

   E.   Riparian Areas: Located within areas of special flood hazard, established in section 10-1-6, are areas designated as riparian areas. Since riparian areas provide critical flood management and fish and wildlife habitat, the following provisions apply:

      1.   Preservation or restoration of the inherent natural characteristics of the river and creeks within the floodplain;

      2.   Preservation of riparian vegetation and wildlife habitat, if any, along the stream bank and within the required minimum twenty five foot (25') setback or riparian zone;

      3.   No development or other than development by the city of Eagle or required for emergency access shall occur within the twenty five foot (25') riparian zone with the exception of approved stream stabilization work. The city council may approve access to property where no other primary access is available. Private pathways and staircases shall not lead into or through the riparian zone unless deemed necessary by the Eagle city council;

      4.   Plan and time frame shall be provided for restoration of riparian vegetation damaged as a result of the work done;

      5.   New or replacement planting and vegetation shall include plantings that are low growing and have dense root systems for the purpose of stabilizing stream banks and repairing damage previously done to riparian vegetation. Examples of such plantings include: red osier dogwood, common chokecherry, serviceberry, elderberry, river birch, skunk bush sumac, Bebb's willow, Drummond's willow, little wild rose, gooseberry, and honeysuckle.

   F.   Map And Narrative Required: All subdivision proposals and development permit applications shall provide a map and detailed narrative describing any abutting or on site manmade topographic features, current or proposed, that increase flood damage potential above the natural level, including road fills and other manmade embankments, prior stream channelization, existing and/or proposed landscaping features, and evident agricultural land leveling that has altered the floodplain from its original topography.

   G.   Fill Requirements: For fill placed in the floodplain:

      1.   Development within the area of special flood hazard shall result in no net loss in natural storage. Grading plans shall show that existing natural storage volume in the floodplain, as bounded by the existing surface topography and the base flood elevation surface, shall not be reduced from the current quantity. Postdevelopment storage volumes will be calculated from the postdevelopment flood elevation for the base flood event. Depressions which will be filled with groundwater and sections of the floodplain which are restricted from floodwater conveyance due to roads built above the base flood elevation shall not be considered when determining storage volumes. Development within the DDA, TDA or CEDA design review overlay areas shall not be subject to the provisions of this subsection.

      2.   The slope of fill adjacent to the floodway line, hereinafter called the floodway boundary slope, shall not be steeper than five horizontal to one vertical (5:1). Where a five to one (5:1) slope is not feasible due to lot dimensions, compensating measures to protect against floodway encroachment through erosion shall be constructed as designed and certified by a professional engineer, architect, or landscape architect.

      3.   The floodway boundary slope shall be maintained in groomed perennial turf or equivalent low ground cover vegetation not taller than twelve inches (12") to provide protection from erosion. Porous stonework or other durable surfacing may be used in lieu of ground cover vegetation for design enhancement on floodway boundary slopes.

   H.   Roadways And Manholes: Roadways and manholes within the floodplain shall be a minimum of one half foot (0.5') above base flood elevation at centerline and manhole ring respectively.

   I.   Flow Paths And Natural Storage Areas Maintained: New roads built above the base flood elevation shall not restrict conveyance of floodwater into sections of the floodplain that may be cut off by the proposed road. Culverts or bridges shall be provided under roads to maintain existing natural storage areas in the watershed to reduce flood damage.

   J.   Open Areas: Except for required berms, open areas such as parks, golf courses, greenbelt areas, parking lots, and the like, within the area of special flood hazard shall be designed and operated so that they may flood and maintain existing natural storage capacity for waters during the base flood event. Levees or berms shall not be used for flood control.

   K.   Approval Of Plans: Plans for development within the floodplain showing construction and postconstruction best management practices (BMPs) conforming to the catalog of stormwater best management practices for Idaho cities and counties shall be submitted for approval before any grading or other construction activities commence.

   L.   Flood Study: When a new flood study is provided by the developer:

      1.   The study shall be performed using the U.S. army corps of engineers hydrologic engineering center's HEC-2, HEC-RAS (river analysis system), or equivalent programs to calculate water surface elevations.

      2.   The study report shall include field survey data and relevant bench marks used as bases of calculations as cross sections, stream profile and plan showing cross section locations.

      3.   The study report shall attach HEC-2, HEC-RAS, or equivalent input and output reports as appendices.

      4.   Any floodway or floodplain modification shall not be effective until approved by FEMA.

      5.   The study shall include a reach of stream extending beyond the property boundaries of the development upstream and downstream not less than twice the average width of floodway on or adjacent to the development property, or as approved by the zoning administrator.

   M.   Critical Facilities: Critical facilities shall not be allowed within any SFHA, special flood hazard area, including areas designated zone shaded X: .2% chance of flooding in any given year.

   N.   Alteration Of Watercourses:

      1.   If a watercourse is to be altered or relocated, the following shall all be submitted by the permit applicant prior to issuance of a floodplain development permit:

         a.   Notify adjacent communities and the Idaho Department of Water Resources prior to any alteration or relocation of a watercourse and submit evidence of such notification to FEMA;

         b.   A description of the extent of watercourse alteration or relocation;

         c.   A professional engineer's certified report that assures the flood-carrying capacity within the altered or relocated portion of the watercourse is maintained and the effects to properties located both upstream and downstream;

         d.   A map showing the location of the proposed watercourse alteration or relocation;

         e.   The proposal is shown to be a permanent solution and creates a stable situation;

         f.   No increase to the one hundred (100) year floodplain upstream or downstream requires certification by a registered Idaho engineer;

         g.   The recreational use of the stream, including access along any and all public pedestrian/fisher's easements and the aesthetic beauty, shall not be obstructed or interfered with by the proposed work;

         h.   Fish habitat shall be maintained or improved as a result of the work proposed;

         i.   The proposed work shall not be in conflict with the local public interest, including, but not limited to, property values, fish and wildlife habitat, aquatic life, recreation and access to public lands and waters, aesthetic beauty of the stream and water quality;

         j.   The work proposed is for the protection of the public health, safety and/or welfare such as public schools, sewage treatment plant, water and sewer distribution lines and bridges providing particularly limited or sole access to areas of habitation;

         k.   An Idaho stream channel alteration permit approval from the Idaho department of water resources shall be provided by the applicant to the floodplain administrator.

(Ord. 700A, 3-11-2014; amd. Ord. 815, 7-23-2019)