6.070 General Provisions.
The provisions of this chapter are applicable to all Areas of Special Flood Hazard within the City of Petaluma.
A. Compliance. No structure or land shall hereafter be constructed, located, extended, converted, or altered without full compliance with the term of this article and other applicable regulations. Violations of the provisions of this article by failure to comply with any of its requirements (including violations of conditions and safeguards established in connection with conditions) shall constitute a misdemeanor. Nothing herein shall prevent the City Council from taking such lawful action as is necessary to prevent or remedy any violation.
1. Abrogation and Greater Restrictions. This article is not intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this article and another article, easement, covenant or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.
2. Interpretation. In the interpretation and application of this article, all provisions shall be:
a. Considered as minimum requirements;
b. Liberally construed in favor of the governing body; and
c. Deemed neither to limit nor repeal any other powers granted under state statutes.
B. Development Permit Required. No structure or land shall hereafter be located, extended, converted or altered within FP-C (Flood Plain-Combining Zone) or within FW (Floodway Zone) lands without having first received a “development permit” in accordance with the provisions of this article; and for developments requiring use permits, with the provisions of Section 24.060.
Development permit applications shall be reviewed by the Planning Director and the requirements of this ordinance enforced in accordance with Chapter 26 (Enforcement, Violations and Penalties) of this Zoning Ordinance.
Application for a Development Permit shall be made on forms furnished by the Floodplain Administrator and may include, but not be limited to: plans drawn to scale showing the nature, location, dimensions, and elevation of the area in question; existing or proposed structures, fill, storage of materials, drainage facilities; and the location of the foregoing. Specifically, the following information is required:
1. Proposed elevation in relation to mean sea level, of the lowest floor (including basement) of all structures; in Zone AO or VO, elevation of the highest natural grade and lowest proposed elevation of lowest floor of all structures.
2. Proposed elevation in relation to mean sea level to which any structure will be floodproofed;
3. All appropriate certifications listed in Section 6.080(C) of this ordinance; and
4. Description of the extent to which any watercourse will be altered or relocated as a result of proposed development.
C. Designation of the Floodplain Administrator. The Planning Director or his/her designee is hereby appointed to administer and implement this ordinance by granting or denying development permits in accordance with its provisions.
D. Residential Construction (Except Mobile Home Parks). New construction and substantial improvement/substantial damage of any residential structure permitted in FP-C (floodplain-combining) zones shall have the lowest habitable floor, including basement, and all machinery and equipment including but not limited to electrical, heating, ductwork, ventilation, plumbing, and air conditioning, elevated at least 12 inches above the level of the base flood elevation or depth number specified on the FIRM (flood insurance rate map), whichever applies to the area, unless otherwise restricted in subsection (D)(2) 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, to be properly elevated. The datum for this elevation shall be as specified in this article. Such certification or verification shall be provided to the floodplain administrator.
1. Manufactured Home Parks. No new manufactured homes shall be placed within floodway areas. Existing manufactured home parks within floodplain areas may be expanded and new manufactured home parks constructed only when the lowest floor of each manufactured home, and substantially improved/damaged, reconstructed manufactured homes; including all machinery and equipment including but not limited to electrical, heating, ductwork, ventilation, plumbing, and air conditioning; of such park is elevated at least 12 inches above the base flood elevation on reinforced piers or other foundation elements equal in force, unless otherwise restricted in subsection (D)(2) of this section, and adequate access and drainage are provided. Existing manufactured home parks in floodway areas may not be expanded under any circumstances.
All applications for new manufactured home parks/subdivisions, or 10 percent or greater physical expansion in the number of manufactured homes existing prior to the adoption of the ordinance codified in this section, located in a floodplain, shall include an emergency evacuation plan describing how property and life will be protected in the event of flooding.
2. Zero Net Fill. A zero net fill policy covers the area along the Petaluma River west of the freeway, upstream of the Payran Street Bridge and including the area east of the freeway and west of Old Redwood Highway (the majority of this area is known generally as Redwood Business Park II). In this area, clearance above base 100 year flood elevation for finished floors shall be a minimum of two feet, and zero net fill as defined shall apply to any proposed development activity.
E. Nonresidential Construction. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall be subject to the restrictions of this article, and shall either have the lowest floor, including basement, elevated 12 inches or more above the level of the base flood elevation or depth number specified on the FIRM (Flood Insurance Rate Map) unless otherwise restricted in Section 6.070(E)(4); or, together with attendant utility and sanitary facilities, shall:
1. 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 hydrostatic and hydrodynamic loads and effects of buoyancy; and
3. 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.
F. Zero Net Fill. A zero net fill policy covers the area along the Petaluma River west of the freeway, upstream of the Payran Street Bridge and including the area along Willowbrook Creek east of the freeway downstream of Old Redwood Highway (this area know generally as Redwood Business Park II). In this area, clearance above base 100 year flood elevation for finished floors shall be a minimum of two feet, and zero net fill as defined shall apply to any proposed development activity.
G. Standards of Construction. In all areas of special flood hazards designated FP-C, the following standards are required:
1. 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 hydrostatic loads, including the effects of buoyancy.
b. All manufactured homes shall meet the anchoring standards of subsection (G)(6) of this section.
2. Construction Materials and Methods.
a. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
b. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
c. 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. Reference subsection (D) of this section for minimum freeboard requirements.
d. All new construction and substantial improvements within zones AH, AO, or VO shall provide adequate drainage paths around structures on slopes to guide flood waters around and away from proposed structures.
3. Elevation and Floodproofing.
a. All new construction and substantial improvements, shall insure 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:
1) 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
2) Be certified to comply with a local floodproofing standard approved by the Federal Insurance Administration.
b. Manufactured homes shall also meet the standards in Section 6.070 (F6).
4. Utilities.
a. 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;
b. On-site water and sewage disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
5. Subdivision Proposals. All subdivision proposals shall comply with the following requirements:
a. Subdivision Design. All subdivision proposals shall be consistent with the need to minimize flood damage.
b. Subdivisions - Utilities. All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage.
c. Subdivisions - Drainage. All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage.
d. Street Elevation Data. Base flood elevation data shall be provided for all subdivision proposals within FP-C (Flood Plain-Combining Zone) lands.
e. Subdivisions - Erosion Control. The perimeters of all earth pads permitted within (FP-C) floodplain areas shall be engineered to prevent erosion of the pad due to water velocities of base flood. A registered professional engineer shall certify that this subsection is satisfied and a copy of such certification shall be provided to the City Engineer and Chief Building Official.
f. Subdivisions - Storage in Areas of Special Flood Hazard. The storage or processing of materials that are in time of flooding buoyant, explosive, or could be injurious to property, structures, human, animal or plant life is prohibited in FP-C and F-W districts.
g. Subdivisions - Certification of Floodproofing. All structures requiring flood proofing shall be so designed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capacity of resisting hydrostatic and hydrodynamic loads with effects of buoyancy. A registered professional engineer or architect shall certify that the standards of this subsection are satisfied and a copy of such certification shall be provided to the Director of Public Works and the Chief Building Official.
6. Standards for Manufactured Homes. 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. (Ord. 2811 § 4, 2022; Ord. 2772 § 2, 2021.)