Article IV — PROVISIONS FOR FLOOD HAZARD REDUCTION

In all areas of special flood hazards the following standards are required.

(A) Anchoring.

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

(2) All manufactured homes shall meet the anchoring standards of § 17.068.240.

(B) Construction materials and methods.

(1) All new construction and substantial improvements shall be constructed with materials and utility equipment resistant 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.

(4) Require within Zones AH or AO, adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures.

(C) Elevation and floodproofing.

(1) New construction and substantial improvement of any structure shall have the lowest floor, including basement, elevated to or above the base flood elevation. Non-residential structures may meet the standards in division (C)(3) of this section. Upon the completion of the structure the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, or verified by the community’s Building Inspector be properly elevated. Such certification or verification shall be provided to the Floodplain Administrator.

(2) New construction and substantial improvement of any structure in Zone AO shall have the lowest floor, including basement, above the highest adjacent grade at least as high as the depth number specified in feet on the FIRM, or at least two feet if no depth number is specified. Nonresidential structures may meet the standards in division (C)(3) of this section. Upon the completion of the structure the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, or verified by the Building Inspector to be properly elevated. Such certification or verification shall be provided to the Floodplain Administrator.

(3) Nonresidential construction shall either be elevated in conformance with divisions (C)(1) or (2) of this section or together with attendant utility and sanitary facilities:

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

(b) Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and

(c) Be certified by a registered professional engineer or architect that the standards of this subsection are satisfied. Such certifications shall be provided to the Floodplain Administrator.

(4) Require, for all new construction and substantial improvements, that fully enclosed areas below the lowest floor that 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 registered professional engineer or architect or meet or exceed the following minimum criteria:

(a) Either a minimum of two openings 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. The bottom of all openings shall be no higher than one 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; or

(b) Be certified to comply with a local floodproofing standard approved by the Federal Insurance Administration.

(5) Manufactured homes shall also meet the standards in § 17.068.240.

(Prior Code, § 17.36.210) (Ord. 577, passed - -1988)

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

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

(Prior Code, § 17.36.220) (Ord. 577, passed - -1988)

(A) All preliminary subdivision proposals shall identify the flood hazard area and the elevation of the base flood.

(B) All final subdivision plans will provide the elevation of proposed structure(s) and pads. If the site is filled above the base flood, the final pad elevation shall be certified by a registered professional engineer or surveyor and provided to the Floodplain Administrator.

(C) All subdivision proposals shall be consistent with the need to minimize flood damage.

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

(E) All subdivisions shall provide adequate drainage to reduce exposure to flood hazards.

(Prior Code, § 17.36.230) (Ord. 577, passed - -1988)

All new and replacement manufactured homes and additions to manufactured homes shall:

• (A) Be elevated so that the lowest floor is at or above the base flood elevation; and

(B) Be securely anchored to a permanent foundation system to resist flotation, collapse or lateral movement.

(Prior Code, § 17.36.240) (Ord. 577, passed - -1988)

Located within areas of special flood hazard established in § 17.068.070 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential, the following provisions apply:

(A) Prohibit encroachments, including fill, new construction, substantial improvements, and other development unless certification by a registered professional engineer or architect is provided demonstrating that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge.

(B) If division (A) of this section is satisfied, all new construction and substantial improvements shall comply with all other applicable flood hazard reduction provisions of this article.

(Prior Code, § 17.36.250) (Ord. 577, passed - -1988)

(A) The Floodplain Administrator shall review permits for proposed construction or other development to determine if it is proposed within a mudslide area.

(B) Permits shall be reviewed to determine that the proposed development is reasonably safe from mudslide hazards. Factors to be considered in making this determination include but are not limited to:

• (1) The type and quality of soils;

• (2) Evidence of ground water or surface water problems;

• (3) The depth and quality of any fill;

• (4) The overall slope of the site; and

• (5) The weight that any proposed development will impose on the slope.

• (C) Within areas which have mudslide hazards, the following requirements apply:

• (1) A site investigation and further review shall be made by persons qualified in geology and soils engineering;

(2) The proposed grading, excavation, new construction and substantial improvements shall be adequately designed and protected against mudslide damages;

(3) The proposed grading, excavations, new construction and substantial improvements do not aggravate the existing hazard by creating either on-site or off-site disturbances; and

• (4) Drainage, planting, watering and maintenance shall not endanger slope stability.

(D) Within Zone M on the Flood Insurance Rate Map, the community shall adopt a drainage ordinance which at least complies with the standards of §§ 7001 through 7006 and §§ 7008 through 7015 of the most recent amendment of the 1973 Uniform Building Code:

• (1) The location of foundation and utility systems of new construction and substantial improvements;

• (2) The location, drainage and maintenance of all excavations, cuts and fills and planted slopes;

(3) Protective measures including but not limited to retaining walls, buttress fills, subdrains, diverter terraces, benchings and the like; and

(4) Engineering drawings and specifications to be submitted for all corrective measures, accompanied by supporting soils engineering and geology reports.

(Prior Code, § 17.36.260) (Ord. 577, passed - -1988)