159.314 Provision For Flood Hazard Reduction

1. Standards for developing lots located in both Zone A and C . If a portion of a lot is situated in a special flood hazard area (such as the 100-year floodplain) and another portion of the lot is outside of the 100-year floodplain, and there is a feasible building site on this latter portion, including grading and associated construction, then the structure, grading and associated construction shall be located outside of the special flood hazard area. If a discrepancy exists between other city requirements, such as setbacks and this requirement to build outside the 100-year floodplain, then this will necessitate that the applicant exhaust the Planning Department's (or other department's) variance process before any consideration is given to allowing the applicant to proceed with construction within the 100-year floodplain.

2. Standards of construction . In all areas of special flood hazards the following standards are required:

   1. Anchoring .

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

      2. All manufactured homes shall meet the anchoring standards of division (E) below.

   2. Construction materials and methods .

      1. All new construction and substantial improvements shall be constructed with materials and utility equipment resistance to flood damage.

      2. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.

      3. All new construction and substantial improvements shall be constructed with electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.

   3. Elevation and floodproofing .

      1. New construction and substantial improvement of any structure shall have the lowest floor, including basement, elevated a minimum of one foot above the base flood elevation. It is recommended that the finish floor be a minimum of 2 feet above the base flood elevation in order to prevent inundation of floor joists, insulation and other appurtenant components located on the underside of the finish floor. Nonresidential structures may meet the standards in division (B) (3)(b) below. Upon the completion of the lowest floor of the structure and prior to any construction above the lowest floor, including framing, the elevation of the lowest floor, including basement, shall be certified by a California registered civil engineer or licensed land surveyor, to be properly elevated. The certification or verification shall be provided to the Floodplain Administrator. The preferred form for this is the elevation certificate, available at the Public Works Department.

      2. Non-residential construction shall either be elevated to conform with division (B)(3)(a) above or together with attendant utility and sanitary facilities:

3. Be floodproofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water;

     2. Have structural components capable of resisting impact, hydrostatic and hydrodynamic loads and effects of buoyancy; and 
   
     3. Be certified by a California registered civil engineer or architect that the standards of this division are satisfied. An architect is limited to certifying the flood proofing and structural design requirements of this division, and is not to perform surveys, certify elevations, or perform hydrology, hydraulic and drainage studies as may be required by this division. The certifications shall be provided to the Floodplain Administrator. 
   

   3. Require for all new construction and substantial improvements, that fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a California registered civil engineer or architect or meet or exceed the following minimum criteria:

      1. Either a minimum of 2 openings having a total net area of not less than 1 square inch for every square foot of enclosed area subject to flooding shall be provided; or (The bottom of all openings shall be no higher than 1 foot above grade. Openings may be equipped with screens, louvers, valves or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.)

      2. Be certified to comply with a local floodproofing standard approved by the Federal Insurance Administration, Federal Emergency Management Agency.

   4. Manufactured homes shall also meet the standards in division (E) below.

4. Standards for utilities .

   1. All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the system and discharge from systems into flood waters.

   2. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

   3. Other utilities are addressed at division (B)(2) above or division (D)(4) below.

5. Standards for subdivisions .

   1. All preliminary subdivision proposals shall identify the flood hazard area and the elevation of the base flood.

   2. 1. All final subdivision plans will provide the elevation of proposed structure(s) and pad(s). The final pad elevation shall be certified by a California registered civil engineer or licensed land surveyor and provided to the Floodplain Administrator. This certification shall be done prior to construction of the foundation or at the completion of final grading, whichever comes first.

      2. No construction is allowed until the certification has been received and approved by the Floodplain Administrator.

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

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

   5. All subdivisions shall provide adequate drainage to reduce exposure to flood hazards.

7. Standards for manufactured homes . All manufactured homes that are placed or substantially improved within a special flood hazard area on the community's flood insurance rate map:

   1. Outside of a manufactured home park or subdivision;

   2. In a new manufactured home park or subdivision;

   3. In an expansion to an existing manufactured home park or subdivision; and

   4. In an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage as the result of a flood:

      1. Be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to a minimum of 1 foot above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation collapse and lateral movement.

      2. All manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision on the community's flood insurance rate map that are not subject to the provisions of this division (E) will be elevated so that either:

         1. The lowest floor of the manufactured home is a minimum of 1 foot above the base flood elevation; or

         2. The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than 36 inches in height above grade and be securely anchored to an adequately anchored foundation system to resist floatation, collapse and lateral movement.

8. Standards for recreational vehicles . All recreational vehicles placed on sites within a floodplain shown on the community's flood insurance rate map will either:

   1. Be on the site for fewer than 180 consecutive days;

   2. Be fully licensed and ready for highway use; or

9. Meet the permit requirements of § 159.313 and the elevation and anchoring requirements for manufactured homes in division (E) above.

10. Floodways .

    1. Located within areas of special flood hazard established in § 159.312 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles and erosion potential, the following provisions apply:

       1. Prohibit encroachments, including fill, new construction, substantial improvements and other new development unless certification by a California registered civil engineer is provided demonstrating that encroachments shall not result in any increase in flood levels during the

occurrence of the base flood discharge.

  2. If this division (G)(1) is satisfied, all new construction and substantial improvements and other proposed new development shall comply with all other applicable flood hazard reduction provisions of this subchapter.

2. A variance to the cumulative damages provision of this subchapter may be granted by the Floodplain Administrator provided;

   1. A variance from these sections is formally requested from an applicant;

   2. The time period for calculating cumulative damages/ improvements occurred prior to January 8, 1995.

3. Flood Zone "A" building permit applicants . The following summarizes sections of the Flood Damage Prevention Ordinance for building permit applicants who may be located in Flood Zone A and specifies steps to take in obtaining a building permit:

   1. A California Registered Civil Engineer is required to prepare an engineering study. The engineer must evaluate the building site and make a determination as to whether the proposed structure will be located within the 100-year floodplain.

      1. The engineering study will involve preparing a topographic site map (related to the National Geodetic Vertical Datum of 1929), perform hydrologic and hydraulic studies and other related engineering calculations required to determine the location of the 100-year floodplain unless specifically exempted by the Floodplain Administrator.

      2. The engineering study must show that the proposed structure will not aggravate flooding problems on adjacent properties.

   2. If it can be shown, via the engineering study, that the proposed structure will not encroach into the 100-year floodplain, no special

   • "floodproofing" construction measures will be required. (Note - in accordance with division (A) above, if a feasible building site exists outside of the 100-year floodplain, no building and associated construction activities are allowed in the 100-year floodplain).

   3. If the structure does encroach into the 100-year floodplain, the engineering study must include the accompanying wind, hydrodynamic, hydrostatic, impact and buoyant forces, as they apply, on the structure. These forces must be included in the design of the structure (see FEMA 114/September, 1986, "Design Manual for Retrofitting Floodprone Residential Structures").

   4. In accordance with division (B0 above, the following shall also apply to construction within the 100-year floodplain.

      1. Single-family dwellings must have their lowest floors elevated a minimum of 1 foot above the 100-year flood elevation. It is recommended that the lowest floor be elevated a minimum of 2 feet in order to prevent inundation of floor joists, insulation and the like. Floodproofing requirements must be satisfied.

      2. Non-residential construction (such as garages, storage sheds and the like) must meet 1 of the following standards:

         1. Be elevated such that the lowest floor is elevated a minimum of one foot above the 100-year flood level; (Two feet is recommended, in accordance with criteria set forth for new construction and substantial improvements.)

         2. Be flood proofed so that below the 100-year flood level the structure is watertight; and

4. Be vented (1 square inch of vent for every square foot of enclosed area). This permits flood waters to enter and exit a structure at the same time, allowing hydrostatic flood forces to equalize on exterior walls. The bottom of all openings shall be no higher than 1 foot above grade. A minimum of 2 vents per structure is required. Venting also applies to the crawl space area under elevated residential structures if the crawl space is enclosed. (Note - venting is the easiest and most economical method to comply with).

   3. All electrical outlets, heating, venting and air condition (HVAC) units, hot water heaters, washing machines, dryers and like appurtenances must be elevated a minimum of 1 foot above the 100-year floodplain.

   4. In accordance with § 159.313, encroachment is prohibited unless the engineering study can show that there will be no increase in the 100-year flood elevation.

(1973 Code, § 9-4.2205) (Ord. 98-3, eff. 7-1-1998)