Portola Municipal Code § 17.28.020 Floodplain (FP)

The overlay and special purpose zone districts established by this title provide guidance for development and new land uses in addition to the standards and regulations of the applicable zoning districts, where important site, neighborhood, or area characteristics require particular attention in project planning.

(Ord. 289 § 2 (Exh. A (part)), 2002)

A. Purpose. It is the purpose of this section to promote the public health, safety, and general welfare, and to minimize those losses described in subsection B of this section by provisions designed to:

1. Restrict or prohibit uses that are dangerous to health, safety, or property in times of flood, or cause increases in flood heights or velocities;

2. Require that uses vulnerable to floods, including public facilities that serve such uses, be protected against flood damage at the time of initial construction;

3. Protect individuals from buying lands that are unsuited for intended purposes because of flood hazard;

4. Avoid unnecessary expenditures of public funds to remedy flood hazards resulting from imprudent uses of lands vulnerable to floods;

5. Maintain and preserve the existing stream channels and stream vegetation in as nearly natural condition as possible in order to preserve wildlife and fish habitat as well as to avoid the expenditure of public funds to remedy or avoid flood hazards, unnatural watercourse diversion, erosion, or situations caused by piecemeal alterations of natural watercourses and flood carrying areas, while balancing this need against the need to reduce the physical area of the floodplain; and

6. Have individual property owners assume responsibility for their actions.

B. Findings of Fact.

1. The areas of special flood hazard of the City of Portola are subject to periodic inundation which results in property, health, and safety hazards; disruption of commerce and governmental services; extraordinary public expenditures for flood protection and relief; and impairment of the tax base, all of which adversely affect the public health, safety, and general welfare. These flood losses are caused by the cumulative effect of obstructions in areas of special flood hazard that increase flood heights and velocities, and, when structures are inadequately anchored, damage uses in other areas. Uses that are inadequately floodproofed, elevated, or otherwise protected from flood damage also contribute to flood loss.

2. Regulation of areas of special flood hazard is necessary because of the compelling need to insure safety and the availability of flood insurance to the residents of the City of Portola, in that the government of the United States, through the Federal Emergency Management Agency (FEMA) and the Federal Insurance Agency (FIA), requires that these regulations be adopted before flood insurance can be obtained by residents.

C. Definitions.

1. Area of special flood hazard. Land subject to a one percent or greater chance of flooding in any given year.

2. Base flood. The flood level having a one percent chance of being equaled or exceeded in any given year.

3. Flood or flooding. A general and temporary condition of partial or complete inundation of normally dry land area lying outside normal stream channel as result of one or more of the following occurrences or conditions - the overflow of inland or tidal waters, or the unusual and rapid accumulation or runoff of surface waters from any source.

4. Flood insurance. The insurance coverage provided under the National Flood Insurance Program.

5. Flood insurance rate map (FIRM). An official map on which the Federal Insurance Administration has delineated both the areas of special flood hazards and the risk premium zones, on file in the office of the building inspector.

6. Flood, one hundred-year. A flood estimated to occur at an average of once in one hundred years (one percent frequency of occurrence), determined from an analysis of historical flood and rainfall records and computed in accordance with accepted methodology to the satisfaction of the Building Inspector and established by the FIRM.

7. Floodplain. The floodplain refers to those shown in those certain aerial photographic maps and designated as "Official Floodplain Maps" of the City of Portola, kept and maintained in the office of the building inspector as provided by FEMA.

8. Floodproofing. Any combination of structural and nonstructural additions, changes or adjustments to structures which reduce or eliminate flood damage to real estate or improved real property, water, and sanitary facilities, structures, and their contents.

9. Freeboard. The vertical height distance between the water surface elevation of the one hundred-year flood and typically the lowest habitable floor of a building or accessory structure. Freeboard represents a safety factor for flood protection and, as such, is also used in the design of levees and altered stream channels.

10. Lowest floor. The lowest floor of the lowest enclosed area (including basement) of a structure. An unfurnished or flood resistant enclosure, usable solely for vehicular parking, building access, or storage, in an area other than a basement area, is not considered a structure's lowest floor; provided, that such enclosure is not built so as to render the structure in violation of any applicable non-elevation design requirements of this title.

11. Regulatory floodway. The channel of a river, creek, or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than one foot. The regulatory floodway is delineated on the FIRM.

D. Basis for Establishing the Areas of Special Flood Hazard. The areas of special flood hazard identified by the Federal Insurance Administration (FIA) of the Federal Emergency Management Agency (FEMA) in the Flood Insurance Study (FIS) and accompanying Flood Insurance Rate Maps (FIRMs) dated March 2, 2005, and all subsequent amendments and/or revisions, are adopted by reference and declared to be part of this section. The FIS and attendant mapping is the minimum area of applicability of this section and may be supplemented by studies for other areas which allow implementation of this section and which are recommended to the city council by the floodplain administrator. The study and FIRMs are on file at 35 Third Avenue, P.O. Box 1225, Portola, CA 96122.

E. Applicability of Standards. In any district with which is combined a floodplain (FP) district, the regulations of this section shall apply in addition to those specified elsewhere in this title for such districts. Provided, however, that in the event of conflict between this section and other provisions in this title, the regulations of this section shall govern, and all uses that are not permitted uses or permissible as flood encroachment uses within the floodplain (FP) districts are prohibited.

F. Floodplain (FP) Permitted Uses. The following uses, having a low flood damage potential and not obstructing flood flows, are permitted within the floodplain (FP) district. Provided, however, that no such use shall include structures, fill, or storage of materials or equipment. And further provided, however, that no such use shall adversely affect the capacity of the channels or floodways, or of any tributary to the main stream, drainage ditch, or any other drainage facility or system, nor shall any use increase the water surface elevation of the base flood:

1. Agricultural uses such as general farming, pasture, grazing, outdoor plant nurseries, horticulture, viticulture, truck farming, forestry, sod farming and wild crop harvesting;

2. Accessory industrial-commercial uses such as loading areas, parking areas, airport landing strips;

3. Private and public recreational uses such as golf courses, tennis courts, driving ranges, archery ranges, picnic grounds, boat launching ramps, swimming areas, park, wildlife and nature preserves, game farms, fish hatcheries, shooting preserves, target ranges, trap and skeet ranges, hunting and fishing areas, and hiking and horseback riding trails;

4. Accessory residential uses such as lawns, gardens, parking areas and play areas.

G. Flood Encroachment Uses. The following uses, which may involve structures (temporary or permanent), fill, or storage of materials or equipment, may be permitted within the floodplain (FP) district only upon the issuance of a flood encroachment permit:

1. Uses or structures accessory to uses permitted by Article II (zoning districts and allowable land uses), but not including any structure designed or used for human residence;

2. Circuses, carnivals, and similar temporary or transient amusement enterprises;

3. Drive-in theaters, new and used car lots, temporary roadside stands, and freestanding signs or billboards (where permitted by the sign ordinance of the City of Portola, Portola Municipal Code Title 17.);

4. Extraction of sand, gravel, and other materials;

5. Marinas, boat rentals, docks, piers, and wharves;

6. Railroad, streets, bridges, utility transmission lines, and pipelines;

7. Storage yards for readily transportable equipment, machinery, or materials;

8. Kennels and stables;

9. Other similar uses of a primarily open space nature.

H. Floodplain (FP) District Permitted Uses. The following uses are permitted within the floodplain (FP) district:

1. Any use permitted in subsection F and G;

2. Structures, including residential structures and mobile homes.

I. Standards for Floodplain Use. The following standards shall govern use of land zoned for floodplain (FP) use:

1. General standards. All uses shall comply with the provisions of this subsection. No structure (temporary or permanent), fill (including fill for roads and levees), obstruction, excavation, storage of materials or equipment, or other use is allowed which, acting alone or in combination with existing or future uses: adversely affects the capacity of the regulatory floodway or of areas where base flood elevations have been determined, but floodways have not been determined; increases peak flow; adversely affects the stream channel; increases flood heights; or is likely to have an adverse effect on a proposed use. Consideration of the effects of a proposed use shall be based on a reasonable assumption that there will be an equal degree of encroachment extending for a significant reach on both sides along the stream. All uses shall:

a. Be consistent with the need to minimize flood damage;

b. Be located and constructed to minimize flood damage;

c. Provide adequate drainage to reduce flood hazards.

2. Fill or excavation standards. Uses involving any grading, fill, or excavations shall comply with the following standards, in addition to those in subsection G.

a. Any fill proposed to be deposited in the regulatory floodway must be shown to have some beneficial purpose, and the amount of fill shall not be greater than is necessary to achieve that purpose, as demonstrated by a plan submitted by the owner showing the uses to which the filled land will be put and the final dimensions of the proposed fill or other materials or excavations.

b. Such fill or other materials or area of excavation shall be protected against erosion by rip-rap, vegetative cover, or bulkheading.

3. Standards for structures. All uses involving any structures, whether temporary or permanent, shall comply with the following standards, in addition to those contained in subsection G above.

a. Structures designed or used for human residence are not permitted in the floodplain (FP) zone.

b. Structures shall have a low flood damage potential.

c. Structures shall be constructed and placed on the building site so as to not obstruct the flow of floodwaters.

i. Whenever possible, structures shall be constructed with the longitudinal axis parallel to the direction of floodflow;

ii. Structures shall be firmly anchored to prevent flotation, collapse, or lateral movement resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.

d. Service or utility facilities, such as electrical and heating equipment, shall be constructed at least one foot above the base flood elevation or shall be floodproofed.

e. In all new construction and substantial improvements, 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 must meet or exceed the following minimum criteria: 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, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.

f. Structures, including residential structures, which are constructed on fill shall be elevated so that the lowest floor is at least one foot above the base flood elevation. Nonresidential structures may be floodproofed in compliance with subsection e above in lieu of elevation.

g. All structures shall be certified upon completion in the "as built" condition by a licensed land surveyor or a registered civil engineer permitted to practice land surveying that the elevation of the lowest floors, including any basement, are at least one foot above the base flood elevation, or have been floodproofed in compliance with subsection E above. Provided, that minor additions to existing single family residences may be constructed at the same level as the existing house.

h. Mobile homes shall be elevated above the base flood as provided in subsection f above and shall additionally be anchored as provided in subsection c. All mobile homes erected in the City of Portola must be placed on a foundation, as approved by the city building Inspector and required in the Chapter 15.20 of this code.

i. All construction shall be with materials resistant to flood damage.

4. Storage of material or equipment. All uses involving the storage of materials or equipment shall comply with the following standards, in addition to those in subsection I.

a. The storage or processing of materials that are buoyant, flammable, toxic, explosive, or could be injurious to human, animal, or plant life, in time of flooding, is prohibited.

b. Storage of other material or equipment may be allowed if it is not subject to major damage by floods and is readily removable from the area within the time available after flood warning.

c. All materials or equipment shall be kept anchored or otherwise restrained to prevent them from being carried downstream by floodwaters.

d. This subsection shall not apply to ordinary household/residential items in amounts normally kept in residences.

5. Procedure. Except for those matters required to be accomplished after construction, the project proponent shall demonstrate compliance with the requirements of this section either at the hearing of the approving authority for those projects requiring a flood encroachment permit, or prior to issuance of any building, grading, or occupancy permit for projects not requiring a flood encroachment permit.

J. Criteria for Development Approval. In passing upon such applications for flood encroachment permits, the approving authority shall consider all relevant factors specified in this section and:

1. The danger to life and property due to increased flood heights or velocities caused by encroachments.

2. The danger that materials may be swept onto other lands or downstream to the injury of others.

3. The proposed water supply and sanitation systems, and the ability of these systems to prevent disease, contamination and unsanitary conditions.

4. The susceptibility of the proposed facility and its contents to flood damage, and the effect of such damage on the individual owner.

5. The importance of the services provided by the proposed facility to the community.

6. The requirements of the facility for a waterfront location.

7. The availability of alternative locations not subject to flooding for the proposed use.

8. The compatibility of the proposed use with existing development and development anticipated in the foreseeable future.

9. The compatibility of the proposed use to the general plan and floodplain management program for the area.

10. The safety and availability of access to the property in times of flood for ordinary and emergency vehicles.

11. The expected heights, velocity, duration, rate of rise, and sediment transport of the floodwaters expected at the site.

12. The compatibility of the proposed use with preservation of valuable fish and wildlife habitat.

13. Such other factors which are relevant to the purposes of this section.

K. Conditions Attached to Flood Encroachment Permits. Upon consideration of the factors listed in subsection J above and the purposes of this section, the approving authority may attach such conditions to the granting of flood encroachment permits as it deems necessary to further the purposes of this section. Among such conditions, without limitation because of specific enumeration, may be included:

1. Modification of waste disposal and water supply facilities.

2. Limitations on periods of use and operation.

3. Imposition of operational controls, sureties, and deed restrictions.

4. Requirements for construction of channel modifications, dikes, levees, and other protective measures.

5. Floodproofing measures shall be designed consistent with the base flood protection elevation for the particular area, flood velocities, durations, rate of rise, hydrostatic and hydrodynamic forces, and other factors associated with the base flood. The review body shall require that the applicant submit a plan or document certified by a registered professional engineer that the floodproofing measures are consistent with the base flood protection elevation and associated flood factors for the particular area. The following floodproofing measures, without limitation because of specific enumeration, may be required:

a. Anchorage to resist flotation and lateral movement. In the case of mobile homes or additions to mobile homes, the anchoring shall be by one of the following methods, and shall be certified to in the "as built" condition by a registered professional engineer:

i. An anchoring system designed to withstand at a minimum, horizontal forces of fifteen pounds per square foot and uplift forces of nine pounds per square foot; or

ii. By anchoring the unit's system in compliance with the department of housing and development mobile home construction and safety standards and FEMA manual No. 85, "Manufactured Home Installation in Flood Hazard Areas" (Sept. 1985).

b. Installation of watertight doors, bulkheads, and shutters or similar methods of construction.

c. Reinforcement of walls to resist water pressures.

d. Use of paints, membranes or mortars to reduce seepage of water through walls.

e. Addition of mass or weight to structures to resist flotation.

f. Installation of pumps to lower water levels in structures.

g. Construction of water supply and waste treatment systems so as to prevent the entrance of floodwaters.

h. Pumping facilities or comparable practices for subsurface drainage systems for buildings to relieve external foundation wall and basement flood pressures.

i. Construction to resist rupture or collapse caused by water pressure to floating debris.

j. Installation of valves or controls on sanitary and storm drains which will permit the drains to be closed to prevent backup of sewage and storm waters into the buildings or structures. Gravity draining of basements may be eliminated by mechanical devices.

k. Location of all water supply systems, sanitary sewer systems, on-site waste disposal systems, electrical equipment, circuits and installed electrical appliances in a manner which will assure they are not subject to flooding or infiltration of floodwaters and to provide protection from contamination or inundation by the base flood.

l. Location of any structural storage facilities for chemicals, explosives, buoyant materials, flammable liquids, or other toxic material which could be hazardous to public health, safety, and welfare in a manner which will assure that the facilities are situated at elevations above the height associated with the base flood protection elevation or are adequately floodproofed to prevent flotation of storage containers, or damage to storage containers which could result in the escape of toxic materials into floodwaters.

L. Records. The building inspector shall maintain records of certifications of floor elevations, floodproofing and encroachments as required by law.

M. Maintenance of Pre-existing Uses. Nothing in this section shall be construed to prohibit the normal, ordinary, or necessary maintenance or repair of a pre-existing, nonconforming use or structure in accordance with Chapter 17.37 of this title. It is the intent of this section that current lawful uses of floodprone lands shall be grandfathered and permitted.

N. Violation. It is unlawful for any person to maintain, use, grade, or fill any property zoned Floodplain (FP) in violation of this section, or to violate any condition of a flood encroachment permit granted pursuant to this section, or to violate any other provision of this chapter.

O. Conflict. Where the provisions of this section conflict with another section of this code, the more restrictive language shall govern.

(Ord. 309 § 2, 2005; Ord. 289 § 2 (Exh. A (part)), 2002)

A. Purpose. It is the purpose of this section to allow for the specific creation of an "old town" overlay in the City of Portola. This designation will allow specific parcels to modify a parking requirement based on Section 17.40.030(D). The creation of an old town overlay will allow the city to target parcels the owners of which may be interested in design standards and parking specific to the old town area.

B. Findings of Fact.

1. There are development conditions specific to the parcels located in the old town overlay area that call for specific regulation. These conditions include narrow lots that are not conducive to the provision of off-street parking, narrow streets developed prior to common use of the automobile, and structures of historical importance to the city.

C. Establishment of Old Town Overlay District. The old town overlay District shall constitute that portion of the city identified on the official zoning map as the old town overlay and depicted on the official zoning map in the office of the city clerk.

D. Applicability of Standards. In any district with which is a combined old town (OT) overlay, the standards of the underlying zoning designation shall apply. Provided, however, that in the event of conflict between this section and other provisions in this title, the regulations of this section shall govern.

E. Old Town (OT) Permitted Uses. The uses described in the underlying zoning designation shall apply.

(Ord. 289 § 2 (Exh. A (part)), 2002)

A. Purpose. It is the purpose of this section to allow for the specific creation of a "downtown core" overlay in the City of Portola. The downtown core designation is intended to provide for parcels located along Highway 70 in the City of Portola. This designation will allow specific parcels to modify a parking requirement based on Section 17.40.030(D). The creation of a downtown core overlay will allow the city to target parcels the owners of which may be interested in design standards and parking specific to the downtown core area.

B. Findings of Fact.

1. There are development conditions specific to the parcels located in the downtown core overlay area that call for specific regulation. These conditions include narrow lots that are not conducive to the provision of off-street parking and structures of historical importance to the city.

C. Establishment of the Downtown Core Overlay District. The downtown core overlay district shall constitute that portion of the city identified on the official zoning map as the downtown core overlay and depicted on the official zoning map in the office of the city clerk.

D. Applicability of Standards. In any district with which is a combined downtown core (DC) overlay, the standards of the underlying zoning designation shall apply. Provided, however, that in the event of conflict between this section and other provisions in this title, the regulations of this section shall govern.

E. Downtown Core (DC) Permitted Uses. The uses described in the underlying zoning designation shall apply.

(Ord. 289 § 2 (Exh. A (part)), 2002)

A. Purpose. It is the purpose of the landfill overlay to control operation of landfill operations so that they will not create a health or safety hazard nor cause hardship to adjacent property owners.

B. Findings of Fact.

1. There are conditions specific to landfill areas that call for specific regulation. These conditions include noise, litter, and erosion.

C. Establishment of Landfill Overlay District: The landfill overlay district shall constitute that portion of the city identified on the official zoning map as the landfill overlay and depicted on the official zoning map in the office of the city clerk.

D. Landfill (LF) Permitted Uses. The following uses are permitted within the landfill (LF) overlay:

1. Operation of a Class II sanitary landfill is allowed, conditioned upon assurances of the following:

a. Hours of operation; daily, regular business hours with no operation between seven p.m. and seven-thirty a.m.;

b. Working face shall be confined to one area to reduce dust;

c. Working face cover shall be adequate to reduce spread of disease and litter;

d. An erosion control plan shall be prepared to control runoff and erosion.

E. Landfill (LF) Future Uses. Upon closing of any landfill, the site shall be adequately covered, compacted, and revegetated. Uses then allowed may include those not sensitive to potential gas migration, including agriculture, forestry, open space/conservation, recreation, and storage facilities.

F. Future Prohibited Landfill (LF) Uses. Upon closing of any landfill, no human habitation uses are allowed.

(Ord. 289 § 2 (Exh. A (part)), 2002)

A. Purpose. It is the purpose of this section to allow for a combined land use district known as the precise plan overlay. The precise plan overlay regulations consist of those regulations set forth in this chapter together with the specific regulation in the district(s) or zone(s) which is (are) combined with the precise plan overlay.

Proceedings to establish a precise plan may be initiated by the planning commission, city council, or a property owner, pursuant to Section 17.97.

The purpose of the precise plan overlay is to assure that yards, open space, structures, parking, loading facilities, landscaping, streets, and similar uses and development of land within the district will be located in accordance with an approved precise plan providing for compatible developments with the district and a compatible relationship with development in adjoining districts.

B. Establishment of the Precise Plan (PP) Overlay District. Upon approval of a precise plan, that designation will be depicted as a precise plan (PP) overlay on the official zoning map in the office of the city clerk.

C. Precise Plan. At the time of the application for rezoning, the applicant shall file eight copies of the proposed precise plan, drawn to scale and prepared by a licensed architect, landscape architect, civil engineer, land surveyor, or other qualified land use planner, which proposed precise plan shall precisely indicate:

1. Parcel dimensions in distances and bearings;

2. All existing and proposed buildings and structures-locations;

3. Yards and open spaces between buildings;

4. Enclosures, walls, fences including, location, heights, and materials;

5. Off-street parking, including location number of spaces, dimensions of parking areas, and internal circulation patterns;

6. Access, including pedestrian, vehicular, service; points of ingress and egress, internal circulation, design, and improvements;

7. Signs, including location, size and height, types of materials, test, and lighting;

8. Loading, including location, dimensions, number of spaces and internal circulation;

9. Open storage areas, including location and use;

10. Landscaping, including location of all existing trees twenty feet or higher, proposed landscaping plan indicating location and type of trees, shrubs, and groundcovers;

11. Lighting, including location and general nature;

12. Street dedications and improvements;

13. Such other data as may be required under the circumstances of each application to permit the planning commission to properly consider the application.

D. Precise Plan (PP) Permitted Uses. The uses permitted in the precise plan overlay are the uses authorized in the district(s) or zone(s) which are combined with the precise plan. If the proposed use requires the issuance of a land use permit, the approval of a precise plan is deemed approval of the land use permit.

E. Yard Requirements. The front, rear, and side yard requirements in the precise plan overlay are those front, rear, and side yard requirements which are shown upon the approved precise plan.

F. Lot Requirements. The area, width, and depth of the lot and percentage of lot coverage in a precise plan overlay are the area, width, and depth requirements established for the land use district(s) or zones(s) which is (are) combined with the precise plan overlay unless variation is necessary due to the peculiarities of the area.

G. Building Height. The height limit in the precise plan overlay is the height limit established for the land use district(s) or zone(s) which is (are) combined with the precise plan overlay unless a variation is appropriate due to the peculiarities of the area.

(Ord. 289 § 2 (Exh. A (part)), 2002)