Petaluma Municipal Code Ch. 6 Floodway and Flood Plain Districts

Sections:

6.010 Purpose.

6.011 Findings of Fact.

6.013 Methods of Reducing Flood Losses.

6.020 Flood Plain and Floodway Areas.

6.030 De:nitions.

6.040 Flood Plain/Flood Prone Area – Combining District (FP-C).

6.050 Floodway District (FW).

6.060 Prezoning of Flood Hazard Lands.

6.070 General Provisions.

6.080 Duties and Responsibilities of the Community Development Department.

6.090 Warning and Disclaimer of Liability.

To establish land use regulations for properties situated in Moodways and Mood plain lands so as to:

A. Minimize property damage from Mood waters and safeguard public health, safety, and general welfare.

B. Protect human life and health.

C. Minimize expenditures of public money for costly Mood control projects.

D. Minimize the need for rescue and relief eOorts associated with Mooding and generally undertaken at the

expense of the general public.

E. Minimize prolonged business interruptions.

F. Minimize damage to public facilities and utilities such as water and gas mains, electric, telephone and sewer

lines, streets and bridges located in areas of special Mood hazards.

G. Help maintain a stable tax base by providing for the sound use and development of areas of special Mood

hazard so as to minimize future Mood blight areas.

H. Insure that potential buyers are notiLed that property is in an area of special Mood hazard; and

I. Insure that those who occupy the areas of special Mood hazard assume responsibility for their actions.

This article is intended to establish speciLc restrictions on the use of those properties or portions of properties

which are situated within the City of Petaluma and within the Petaluma River Basin Flood Plain and Floodway

areas as deLned below, and shall apply to all development within those areas.

A. The Mood hazard areas of the City of Petaluma are subject to periodic inundation which can result in loss of

life and property, health and safety hazards, disruption of commerce and governmental services, extraordinary

public expenditures for Mood protection and relief, and impairment of the tax base, all of which adversely aOect

the public health, safety and general welfare.

B. These Mood losses can be caused by the cumulative eOect of obstructions in areas of special Mood hazards

which increase Mood heights and velocities, and when inadequately anchored, damage uses in other areas. Uses

that are inadequately Moodproofed, elevated, or otherwise protected from Mood damage also contribute to the

Mood loss.

In order to accomplish its purposes, this ordinance includes methods and provisions for:

A. Restricting or prohibiting uses which are dangerous to health, safety, and property due to water or erosion

hazards, or which result in damaging increases in erosion or Mood heights or velocities;

B. Requiring that uses vulnerable to Moods, including facilities which serve such uses, be protected against Mood

damage at the time of initial construction;

C. Controlling the alteration of natural Moodplains, stream channels, and natural protective barriers, which help

accommodate or channel Mood waters;

D. Controlling Llling, grading, dredging, and other development which may increase Mood damage; and

E. Preventing or regulating the construction of Mood barriers which will unnaturally divert Mood waters or which

may increase Mood hazards in other areas.

The Petaluma River Basin Flood Plain and Floodway Areas are deLned as those areas of Special Flood Hazard

identiLed by the Federal Insurance Administration through a scientiLc and engineering report entitled “Flood

Insurance Study for the City of Petaluma”, dated August 1979, with accompanying Flood Boundary and Floodway

Map; and accompanying Flood Insurance Rate Maps. Any oNcial revisions or updates thereto are hereby adopted

by reference and declared to be a part of this Ordinance. This Flood Insurance Study is the minimum area of applicability of this Ordinance and may be supplemented by studies for other areas which allow implementation

of this Ordinance and which are recommended to the City Council by the Floodplain Administrator. Maps and data

which reMect this delineation shall be kept on Lle in the oNce of the Director of the City of Petaluma and shall be

available for public examination at reasonable times.

Unless speciLcally deLned below, words or phrases used in this Ordinance shall be interpreted so as to give them

the meaning they have in common usage and to give this ordinance the most reasonable application.

A. Alter. In the context of this Article and the changing of a riverine or drainage channel, shall mean any activity

which decreases, increases, or otherwise causes changes to the carrying capacity of said riverine or drainage

channel.

B. Appeal. A request for a review of the Floodplain Administrator’s interpretation of any provision of this

ordinance or a request for a variance.

C. Area of Shallow Flooding. A designated AO, AH, or VO zone on the Flood Insurance Rate Map (FIRM). The base

Mood depths range from one to three feet; a clearly deLned channel does not exist; the path of Mooding is

unpredictable and indeterminate; and, velocity Mow may be evident.

D. Area of Special Flood Hazard. The land in the Mood plain within a community subject to a one percent or

greater chance of Mooding in any given year.

E. Base Flood. The Mood having a one percent chance of being equaled or exceeded in any given year (also called

the “100 year Mood”).

F. Basement. Any area of the building having its Moor subgrade, i.e., below ground, level on all sides.

G. Breakaway Walls. Any type of wall, whether solid or lattice, and whether constructed on concrete, masonry,

wood, metal, plastic or any other suitable building material which is not part of the structural support of the

building and which is designed to break away under abnormally high tides or wave action without causing any

damage to the structural integrity of the building on which they are used or any buildings to which they might be

carried by Mood waters. A breakaway wall shall have a safe design loading resistance of not less than ten and no

more than twenty pounds per square foot. Use of breakaway walls must be certiLed by a registered engineer or

architect and shall meet the following conditions:

1. Breakaway wall collapse shall result from a water load less than that which would occur during the base

Mood; and

2. The elevated portion of the building shall not incur any structural damage due to the eOects of wind and

water loads acting simultaneously in the event of the base Mood.

H. Coastal High Hazard Area. The area subject to high velocity waters, including coastal and tidal inundation or

tsunamis. The area is designated on a Flood Insurance Rate Map (FIRM) as Zone V1-V30, VE or V.

I. Development. Any man-made change to improved or unimproved real estate including, but not limited to,

buildings or other structures, mining, dredging, Llling, grading, excavation, drilling operations, permanent storage

of equipment and materials (i.e., lumber yards, junk yards, vehicle storage yards, etc.), excluding the improvement

or maintenance of public roads.

J. Development Permit. A zoning permit, grading permit or building permit or any other permit, certiLcate, or

license pertaining to the erection, construction, reconstruction, moving, conversion, alteration, or addition to any

building or structure and the use of any land, building or premise, per the procedure set forth in Section 6.070(B).

K. Flood or Flooding. A general and temporary condition of partial or complete inundation of normally dry land

areas from: (1) the overMow of inland or tidal waters; (2) the unusual and rapid accumulation or runoO of surface

waters from any source; and/or (3) the collapse or subsidence of land along the shore of a lake or other body of

water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical

levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe

storm, or by an unanticipated force of nature, such as Mash Mood or an abnormal tidal surge, or by some similarly

unusual and unforeseeable event which results in Mooding as deLned in this deLnition.

L. Flood Boundary and Floodway Map. The oNcial map on which the Federal Emergency Management Agency or

Federal insurance Administration has delineated both the areas of Mood hazard and the Moodway.

M. Flood Insurance Rate Map (FIRM). An oNcial map of the City of Petaluma or Sonoma County, on which the

Federal Insurance Administration has delineated both the areas of special Mood hazards and the risk premium

zones applicable to the community.

N. Flood Insurance Study. The oNcial report provided by the Federal Insurance Administration. The report

contains Mood proLles, as well as the Flood Boundary-Floodway Map, the Flood Insurance Rate Maps, and the

water surface elevation of the base Mood.

O. Floodplain or Flood-prone Area. Any land area susceptible to being inundated by water from any source (see

deLnition of Mooding).

P. Floodplain Management. The operation of an overall program of corrective and preventive measures for

reducing Mood damage, including but not limited to emergency preparedness plans, Mood control works, and

Moodplain management regulations.

Q. Floodplain Management Regulations. Zoning ordinances, subdivision regulations, building codes, health

regulations, special purpose ordinances (such as Moodplain ordinance, grading ordinance and erosion control

ordinance), and other applications of police power. The term describes such state or local regulations in any

combination thereof, which provide standards for the purpose of Mood damage prevention and reduction.

R. Floodproofed. Watertight with walls substantially impermeable to the passage of water and with structural

components having the capability of resisting hydrostatic and hydrodynamic loads and eOects of buoyancy.

S. Floodproo4ng. Any combination of structural and nonstructural additions, changes, or adjustments to

structures which reduce or eliminate Mood damage to real estate or improved real property, water and sanitary

facilities, structures and their contents.

T. Floodway. Also referred to as regulatory Moodway. The channel of a river or other watercourse and the

adjacent land areas that must be reserved in order to discharge the base Mood without cumulatively increasing the

water surface elevation more than one (1) foot.

U. Functionally Dependent Use. A use which cannot perform its intended purpose unless it is located or carried

out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the

loading and unloading of cargo or passengers, and ship building and ship repair facilities, but does not include

long-term storage or related manufacturing facilities.

V. Habitable Floor. Any Moor usable for living purposes, which includes working, sleeping, eating, cooking or

recreation, or a combination thereof. A Moor used only for storage purposes is not a “habitable Moor”.

W. Highest Adjacent Grade. The highest natural elevation of the ground surface prior to construction next to the

proposed walls of a structure.

X. Lowest Floor. The lowest Moor of the lowest enclosed area (including basement). An unLnished or Mood

resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a

basement area is not considered a building’s lowest Moor; provided that such enclosure is not built so as to render

the structure in violation of the applicable non-elevation design requirements of this ordinance.

Y. Manufactured Home. A structure, transportable in one or more sections, which is built on a permanent chassis

and is designed for use with or without a permanent foundation when connected to the required utilities. For

Moodplain management purposes, the term “manufactured home” also includes park trailers, travel trailers and

other similar vehicles placed on a site for greater than 180 consecutive days.

Z. Manufactured Home Park or Subdivision. A parcel (or contiguous parcels) of land divided into two or more

manufactured home lots for sale or rent.

AA. Mean Sea Level. For purposes of the National Flood Insurance Program, the National Geodetic Vertical Datum

(NGVD) of 1929 or other datum, to which base Mood elevations shown on a community’s Flood Insurance Rate

Map are referenced.

BB. New Construction. Structures for which the “start of construction” commenced on or after the eOective date of

this Ordinance.

CC. No Net Fill. Any material brought on to a project site within a Mood plain area that would displace Mood

waters. All Lll shall be oOset by the removal of a like amount of material. This material may be removed from a

portion of the project site; or it may be removed from a site in the immediate area where the removal of

compensating material from the oO-site location can be determined, to the satisfaction of the City Engineer and

the Sonoma County Water Agency, to result in a reasonable equivalence of hydrology and hydraulics to the situation before the development. For purposes of compliance, one or more individual parcels or an entire reach

may demonstrate a “zero net Lll” balance.

DD. Petaluma River Basin. All signiLcant Mooding sources aOecting the City of Petaluma including the Petaluma

River, Washington Creek, Lynch Creek, Willow Brook, Thompson Creek, Kelly Creek, Adobe Creek, Capri Creek,

Corona Creek, and several minor tributaries thereto.

EE. Person. An individual or his agent, Lrm, partnership, association or corporation, or agent of the

aforementioned groups, or this state or its agencies or political subdivisions.

FF. Regulatory Floodway. The channel of a river or other watercourse and the adjacent land areas that must be

reserved in order to discharge the base Mood without cumulatively increasing the water surface elevation more

than one foot.

GG. Remedy a Violation. To bring the structure or other development into compliance with State or local

Moodplain management regulations, or, if this is not possible, to reduce the impacts of its noncompliance to a level

acceptable to the City. Ways that impacts may be reduced include protecting the structure or other aOected

development from Mood damages, implementing the enforcement provisions of the ordinance or otherwise

deterring future similar violations, or reducing Federal Lnancial exposure with regard to the structure or other

development.

HH. Riverine. Relating to, formed by, or resembling a river (including tributaries), stream, brook, etc.

II. Special Flood Hazard Area (SFHA). An area having special Mood or Mood-related erosion hazards, and shown on

an FHBM or FIRM as Zone A, AO, A1-30, AE, A99, AH, V0, V1-V30, VE or V.

JJ. Start of Construction. Includes substantial improvements, rehabilitations, additions and reconstructions, and

means the date the building permit was issued, provided the actual start of construction, repair, reconstruction,

placement, or other improvement was within 180 days of the permit date. The actual start means either the Lrst

placement of permanent construction of a structure on a site, such as the pouring of a slab or footings, the

installation of piles, the construction of columns, or any work beyond the stage of excavation; or placement of a

manufactured home on foundation. Permanent construction does not include land preparation, such as clearing,

grading and Llling; nor does it include the installation of streets and/or sidewalks; nor does it include excavation

for a basement, footing, piers, or foundations or the erection of temporary forms; nor does it include the

installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not

part of the main structure.

KK. Structure. A walled and/or roofed building, including a gas or liquid storage tank, that is principally above

ground, as well as a manufactured home.

LL. Substantial Improvement. Any repair, reconstruction, rehabilitation, addition or improvement of a structure,

the cost of which exceeds 50 percent of the market value of the structure, not inclusive of the land value, before

the start of construction of the improvement either (1) before the improvement or repair is started; or (2) if the

structure has been damaged and is being restored, before the damage occurred. For the purposes of this

deLnition, “substantial improvement” is considered to occur when the Lrst alteration of any wall, ceiling, Moor, or other structural part of the building commences, whether or not that alteration aOects the external dimension of

the structure. The term does not, however, (1) include any project for the improvement of a structure to comply

with existing state or local health, sanitary, or safety code speciLcations which are solely necessary to assure safe

living conditions; or (2) any alteration of a structure listed on the National Register of Historic Places or a State of

City Inventory of Historic Places provided that the alteration will not preclude the structure’s continued

designation as a historic structure.

MM. Variance. A grant of relief from the requirements of this ordinance which permits construction in a manner

that would otherwise be prohibited by this ordinance.

NN. Violation. The failure of a structure or other development to be fully compliant with the community’s

Moodplain management regulations. A structure or other development without the elevation certiLcate, other

certiLcations, or other evidence of compliance required in this ordinance is presumed to be in violation until such

time as that documentation is provided.

All areas within the boundaries of the “Area of Special Flood Hazard” but outside the “Floodway” areas are hereby

zoned to the (FP-C) Flood Plain-Combining District.

A. E5ect of Zone. Areas zoned Flood Plain-Combining District (F-C): the regulations of the underlying zoning

district shall be combined with and apply in addition to the provisions of this article. Where any conMict may exist

between the requirements of this ordinance and other zoning districts, the provisions of this article shall apply.

B. Restrictions in Zone. Any permitted principal use, accessory use, or conditional use in any underlying zoning

district shall require a development permit in the FP-C District per Section 6.070(B) and may be permitted only in

accordance with the provisions of this article.

All areas within the boundaries of the “Areas of Special Flood Hazard” and identiLed as “Floodway” areas are zoned

Floodway.

A. Encroachments in Floodway. Since the Moodway is an extremely hazardous area due to the velocity of Mood

waters which carry debris, potential projectiles, and erosion potential, no encroachments within Floodway lands

are permitted; including Lll, new construction, intensiLcation of existing use, change to more intensive use,

substantial improvements, and other development, except as speciLed herein as permitted or conditional land

uses, and provided that a certiLcation by a registered professional engineer or architect is provided demonstrating

that encroachments shall not result in any increase in Mood levels during the occurrence of the base Mood

discharge.

B. Permitted Uses, Floodway Districts. The following uses are permitted upon obtaining a Development Permit per

Section 6.070(B) without a Use Permit where modiLcation or removal of native vegetation, including trees, is not

required:

1. Open space agricultural uses not requiring a fence or closed building such as cropland, orchards, and

livestock feeding and grazing.

2. Circuses, carnivals, and other similar transient amusement enterprises provided a zoning permit has

been obtained from the Community Development Department.

3. Modi4cation of Native or Riparian Vegetation. Where modiLcation or removal of native or riparian

vegetation is required, such modiLcation or removal may be permitted after obtaining a development permit

consisting of written approval from the Director, provided that such proposed modiLcations in the Flood Plain

have been found to be consistent with the General Plan.

4. Any other open type of use as determined by the Zoning Administrator (Director of Planning) to be of the

same general character as the above permitted uses.

5. Periodic dredging of silt material from the navigable portions of the Petaluma River for maintenance

purposes, when said silt material is removed from the Moodway area.

C. Conditional Uses, Floodway District. The following uses may be permitted after approval of a conditional use

permit by the City of Petaluma:

1. Open air public and private recreational facilities such as parks, golf courses, and athletic Lelds.

2. Private and public docking, mooring, and boat launching facilities, providing such facilities shall be

designed and constructed so as not to restrict the carrying capacity of the designated Moodway.

3. Above-ground public utility and private service facilities such as water and sanitation pipe lines,

telecommunication facilities in accordance with Chapter 14.44 of the Petaluma Municipal Code, roads,

bridges, and similar facilities, providing such facilities shall be designed and constructed so as not to restrict

the carrying capacity of the Moodway.

4. Improvements in stream channel alignment, cross section, and capacity including modiLcation of river

bank and Mood protection levels, other than periodic dredging of material from the navigable portions of the

Petaluma River for maintenance purposes, when said material is removed from the Moodway area.

All areas not within the City of Petaluma but within the boundaries of the “Areas of Special Flood Hazard”

identiLed by the Federal Insurance Administration through a scientiLc and engineering report entitled “The Flood

Insurance Study for the County of Sonoma” dated May 31, 1979, or any updates thereto and which are also within

the City of Petaluma planning area as shown on the Petaluma General Plan are hereby prezoned to the FP-C

(Flood Plain-Combining Zone) or FW (Floodway Zone) in accordance with the principles set out in Sections 6.040

through 6.050 and this Chapter.

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 conMict 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 Lrst 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, Lll, storage of materials, drainage facilities; and the location of

the foregoing. SpeciLcally, the following information is required:

1. Proposed elevation in relation to mean sea level, of the lowest Moor (including basement) of all

structures; in Zone AO or VO, elevation of the highest natural grade and lowest proposed elevation of lowest

Moor of all structures.

2. Proposed elevation in relation to mean sea level to which any structure will be Moodproofed;

3. All appropriate certiLcations 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 (Moodplain-combining) zones shall have the

lowest habitable Moor, 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 Mood elevation or depth number speciLed on the FIRM (Mood 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 Moor, including basement, shall be certiLed by a registered professional engineer or

surveyor, to be properly elevated. The datum for this elevation shall be as speciLed in this article. Such

certiLcation or veriLcation shall be provided to the Moodplain administrator.

1. Manufactured Home Parks. No new manufactured homes shall be placed within Moodway areas. Existing

manufactured home parks within Moodplain areas may be expanded and new manufactured home parks

constructed only when the lowest Moor 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 Mood 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 Moodway 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 codiLed in this section,

located in a Moodplain, shall include an emergency evacuation plan describing how property and life will be

protected in the event of Mooding.

2. Zero Net Fill. A zero net Lll 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 Mood elevation for Lnished Moors shall be a minimum of two feet, and zero net Lll as deLned 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

Moor, including basement, elevated 12 inches or more above the level of the base Mood elevation or depth number speciLed 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 Moodproofed so that below the base Mood 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 eOects of

buoyancy; and

3. Be certiLed by a registered professional engineer or architect that the standards of this subsection are

satisLed. Such certiLcations shall be provided to the Floodplain Administrator.

F. Zero Net Fill. A zero net Lll 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 Mood elevation for Lnished Moors shall be a minimum of two feet, and zero net Lll as deLned shall apply to

any proposed development activity.

G. Standards of Construction. In all areas of special Mood hazards designated FP-C, the following standards are

required:

1. Anchoring.

a. All new construction and substantial improvements shall be anchored to prevent Motation, collapse,

or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the

eOects 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 Mood damage.

b. All new construction and substantial improvements shall be constructed using methods and

practices that minimize Mood 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 Mooding. 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 Mood waters around and away from

proposed structures.

3. Elevation and Floodproo4ng.

a. All new construction and substantial improvements, shall insure that fully enclosed areas below the

lowest Moor that are subject to Mooding shall be designed to automatically equalize hydrostatic Mood

forces on exterior walls by allowing for the entry and exit of Moodwaters. Designs for meeting this

requirement must either be certiLed 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 Mooding 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 Moodwaters; or

2) Be certiLed to comply with a local MoodprooLng 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 inLltration of Mood waters into the system and discharge from systems into Mood waters;

b. On-site water and sewage disposal systems shall be located to avoid impairment to them or

contamination from them during Mooding.

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 Mood

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 Mood damage.

c. Subdivisions - Drainage. All subdivision proposals shall have adequate drainage provided to reduce

exposure to Mood damage.

d. Street Elevation Data. Base Mood 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) Moodplain

areas shall be engineered to prevent erosion of the pad due to water velocities of base Mood. A

registered professional engineer shall certify that this subsection is satisLed and a copy of such

certiLcation shall be provided to the City Engineer and Chief Building ONcial.

f. Subdivisions - Storage in Areas of Special Flood Hazard. The storage or processing of materials that are

in time of Mooding 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 - Certi4cation of Floodproo4ng. All structures requiring Mood prooLng shall be so

designed so that below the base Mood 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 eOects of buoyancy. A registered professional engineer or

architect shall certify that the standards of this subsection are satisLed and a copy of such certiLcation

shall be provided to the Director of Public Works and the Chief Building ONcial.

6. Standards for Manufactured Homes. All new and replacement manufactured homes and additions to

manufactured homes shall:

a. Be elevated so that the lowest Moor is at or above the base Mood elevation; and

b. Be securely anchored to a permanent foundation system to resist Motation, collapse or lateral

movement. (Ord. 2811 § 4, 2022; Ord. 2772 § 2, 2021.)

Department.

It shall be the duty of the Community Development Department to:

A. Review all development permits to assure that the permit requirements of this ordinance have been satisLed,

and to insure that construction of development sites are reasonably safe from Mooding.

B. Review permits for proposed development to assure that all necessary permits have been obtained from

those Federal, State or local governmental agencies from which prior approval is required.

C. All records required to be kept pertaining to the provisions of this Chapter shall be maintained in the oNce of

the Planning Department shall be open for public inspection. In regard to this item, the following information is

required to be submitted by the applicant:

1. Elevation in relation to mean sea level, of the lowest habitable Moor (including basement) of all structures

as certiLed by a registered professional engineer or licensed land surveyor;

2. Elevation in relation to mean sea level to which any structure has been Moodproofed;

3. CertiLcation by a registered professional engineer or architect that the MoodprooLng methods for any

nonresidential structure meet the MoodprooLng requirements stated in Section 6.070(E); and

4. Description of the extent to which any watercourse will be altered or altered or relocated as a result or

proposed development.

D. Require as a condition of development approval that maintenance is provided within the altered or relocated

portion of any watercourse aOected or disturbed by the project so that the Mood carrying capacity is not adversely

aOected. For purposes of this article, “adversely aOected” means that the cumulative aOect of the proposed development, when combined with all other existing and anticipated development, will not increase the water

surface elevation of the base Mood more than one foot at any point.

E. Use of Other Base Flood Data. When base Mood elevation data has not been provided in accordance with

Section 6.020, the Floodplain Administrator shall obtain, review, and reasonably utilize any base Mood elevation

and Moodway data available from a Federal, State or other source, in order to administer Section 6.070(F). Any

such information shall be submitted to the City Council for adoption.

F. Whenever a riverine is to be altered or relocated:

1. Notify the California Department of Water Resources prior to such alteration or relocation of a

watercourse, and submit evidence of such notiLcation to the Federal Insurance Administration;

2. Require that the Mood carrying capacity of the altered or relocated portion of said watercourse is

maintained.

G. Obtain and maintain for public inspection and make available as needed:

1. The certiLcation required in Section 6.080(C) (Moor elevations);

2. The certiLcation required in Section 6.070(D) (elevations in areas of shallow Mooding);

   3. The certiLcation required in Section 6.070(E) (elevation or MoodprooLng of non-residential structures).

   4. The certiLcation required in Section 6.070(F)(3) (wet MoodprooLng standard);

   5. The certiLed elevation required in Section 6.070(F)(5) (subdivision standards);

   6. The certiLcation required in Section 6.050(A) (Moodway encroachments).

H. Make interpretations where needed, as to the exact location of the boundaries of the areas of special Mood

hazards (for example, where there appears to be a conMict between a mapped boundary and actual Leld

conditions). The person contesting the location of the boundary shall be given a reasonable opportunity to appeal

the interpretation as provided in Section 24.090.

I. Take action to remedy violations of this article as speciLed in Section 6.070(A) herein. (Ord. 2811 § 4, 2022.)

The degree of Mood protection required by this article is considered reasonable for regulatory purposes and is

based on scientiLc and engineering considerations. Larger Moods can and will occur on occasion. Flood heights

may be increased by man-made or natural causes. This article does not imply that land outside the areas of

special Mood hazards or uses permitted within such areas will be free from Mooding or Mood damages. This article

shall not create liability on the part of the City of Petaluma or by any oNcer or employee thereof for any Mood

damages that result from reliance on this article or any administrative decision made thereunder.

The Petaluma Implementing Zoning Ordinance is current through Ordinance 2907, passed September 8,

Disclaimer: The city clerk’s oNce has the oNcial version of the Petaluma Implementing Zoning Ordinance. Users

should contact the city clerk’s oNce for ordinances passed subsequent to the ordinance cited above.

City Website: cityofpetaluma.net

Hosted by General Code.