Hollister Municipal Code § 15.20.130 Standards of construction

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

A. Anchoring.

1. All new construction, substantial improvements, and other proposed new development shall be adequately 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 Section 15.20.160.

B. Construction Materials and Methods.

1. All new construction, substantial improvement and other proposed new development shall be constructed with materials and utility equipment resistant to flood damage.

2. All new construction, substantial improvement and other proposed new development shall be constructed using methods and practices that minimize flood damage.

3. All new construction, substantial improvement and other proposed new development 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. All new construction, substantial improvement and other proposed new development shall require within zones AH or AO that adequate drainage paths around structures on slopes guide floodwaters around and away from proposed structures.

C. Elevation and Floodproofing.

1. New construction, substantial improvement and other proposed new development shall have the lowest floor, including basement, elevated to or above the base flood elevation. Nonresidential structures may meet the standards in subsection (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 building inspector to be properly elevated. Such certification or verification shall be provided to the floodplain administrator.

2. New construction, substantial improvement, and other proposed new development in zone AO shall have the lowest floor, including basement, elevated 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 subsection (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 building inspector to be properly elevated. Such certification or verification shall be provided to the floodplain administrator.

3. Nonresidential construction shall either be elevated to conform with subsection (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. For all new construction, substantial improvement and other proposed new development, 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 floodwater. 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 floodwater); or

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

5. Manufactured homes shall also meet the standards in Section 15.20.160.

(Prior code § 8A-14; Editorially amended during 1998 codification)

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.

C. Other utilities are addressed at Sections 15.20.130(B) and 15.20.150(D).

(Prior code § 8A-15)

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 pad(s). If the site is filled above the base flood elevation, 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 § 8A-16)

A. 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 (4) in an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage as the result of a flood shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to or above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist floatation collapse and lateral movement.

B. 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 subsection A of this section will be elevated so that either:

1. The lowest floor of the manufactured home is at or 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.

(Prior code § 8A-17)

All recreational vehicles placed on sites within a floodplain shown on the community's Flood Insurance Rate Map will either:

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

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

C. Meet the permit requirements of Article IV of this chapter and the elevation and anchoring requirements for manufactured homes in Section 15.20.160.

(Prior code § 8A-18)

Located within areas of special flood hazard established in Section 15.20.060 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 improvement, and other new 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 subsection A of this section is satisfied, all new construction, substantial improvement and other proposed new development shall comply with all other applicable flood hazard reduction provisions of this article.

(Prior code § 8A-19)