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(A) Lands to which this article applies. This article shall apply to all areas of special flood hazard within the jurisdiction of the city.
(B) Basis for establishing the areas of special flood hazard. The areas of special flood hazard identified by the Federal Emergency Management Agency (FEMA) in the "Flood Insurance Study (FIS) for Contra Costa County, California, and Incorporated Areas" dated June 16, 2009 with an accompanying Flood Insurance Rate Maps (FIRM's) and Flood Boundary and Floodway Maps (FBFM's), dated June 16, 2009, and all subsequent and/or revision, are hereby adopted by reference and declared to be a part of this article. Such Flood Insurance Study is on file in the Department of Public Works. This FIS and attendant mapping is the minimum area of applicability of this article and may be supplemented by studies for other areas which allow the implementation of this article and which are recommended to the city by the Floodplain Administrator. The study, FIRM's and FBFM's are on file at the Community Development Department, Engineering Division, 200 "H" Street, Antioch, CA 94531-5007.
(C) Compliance. No structure or land shall hereafter be constructed, located, extended, converted, or altered without full compliance with the terms 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 set forth in this article shall prevent the Council from taking such lawful action as is necessary to prevent or remedy any violation.
(D) Abrogation and greater restrictions. This article is not intended to repeal, abrogate, or impair any existing easement, covenant, or deed restriction. However, where this article and another law, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.
(E) Interpretation. In the interpretation and application of this article, all provisions shall be:
(1) Considered as minimum requirements;
(2) Liberally construed in favor of the governing body; and
(3) Deemed neither to limit nor repeal any other power granted under state statutes.
(F) Warning and disclaimer of liability. The degree of flood protection required by this article is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur on rare occasions. Flood heights may be increased by man-made or natural causes. This article does not imply that land outside the areas of special flood hazard, or uses permitted within such areas, will be free from flooding or flood damages. This article shall not create liability on the part of the city, or any officer or employee thereof, or the Federal Insurance Administration, for any flood damage which results from reliance on this article or any administrative decision lawfully made thereunder.
(G) Severability. This article and the various parts thereof are hereby declared to be severable. Should any section of this article be declared by the courts to be unconstitutional or invalid, such decision shall not affect the validity of this article as a whole, or any portion thereof, other than the section so declared to be unconstitutional or invalid.
('66 Code, § 9-4.2004) (Ord. 708-C-S, passed 5-12-88; Am. Ord. 2025-C-S, passed 5-12-09)
(A) Establishment of development permits. A development permit shall be obtained before construction or development begins within any area of special flood hazard. Applications for development permits shall be made on forms furnished by the Floodplain Administrator and may include, but not be limited to: plans in duplicate drawn to scale showing the nature, location, dimensions, and elevation of the area in question; existing or proposed structures, fill, storage of materials, and drainage facilities; and the location of the foregoing. Specifically, the following information shall be required:
(1) The proposed elevation, in relation to the mean sea level, of the lowest floor (including the basement) of all structures; in Zone AO, the elevation of the highest adjacent grade and proposed elevation of the lowest floor of all structures;
(2) The proposed elevation in relation to the mean sea level to which any structure will be floodproofed;
(3) All appropriate certifications listed in subdivision (4) of division (C) of this section;
(4) A description of the extent to which any watercourse will be altered or relocated as a result of the proposed development; and
(5) Additional information as required by the Floodplain Administrator.
(B) Designation of the Floodplain Admini-strator. The City Engineer is hereby appointed to administer and implement this article by granting or denying development permits in accordance with the provisions of this article.
(C) Duties and responsibilities of the Floodplain Administrator. The duties and responsibilities of the Floodplain Administrator shall include, but not be limited to:
(1) Review development permits as follows:
(a) Review all development permits to determine that the permit requirements of this article have been satisfied;
(b) All other required state and federal permits have been obtained;
(c) The site is reasonably safe from flooding; and
(d) The proposed development does not adversely affect the carrying capacity of areas where base flood elevations have been determined that a floodway has not been designated. For the purposes of this article, ADVERSELY AFFECTS shall mean that the cumulative effect of the proposed development when combined with all other existing and anticipated development will not increase the water surface elevation of the base flood more than one foot at any point within the city;
(e) All Letters of Map Revision (LOMR's) for flood control projects are approved prior to the issuance of building permits. Building permits must not be issued based on Conditional Letters of Map Revision (CLOMR's). Approved CLOMR's allow construction of the proposed flood control project and land preparation as specified in the "start of construction" definition;
(2) When base flood elevation data has not been provided, the Floodplain Administrator shall obtain, review, and reasonably utilize any base flood elevation and floodway data available from a federal, state, or other source in order to administer §§ 9-4.2007 through 9-4.2011 of this article. Any such information shall be submitted to the Council for adoption;
(3) Alteration or relocation of a watercourse:
(a) Notify adjacent communities and the California Department of Water Resources prior to such alteration or relocation;
(b) Submit evidence of such notification to the Federal Emergency Management Agency; and
(c) Assure that the flood-carrying capacity within the altered or relocated portion of such watercourse is maintained;
(4) Obtain and maintain for public inspection and make available as needed:
(a) The certification required by subdivision (B)(3)(a) of § 9-4.2007 of this article (floor elevations);
(b) The certification required by subdivision (B)(3)(b) of § 9-4.2007 of this article (elevations in areas of shallow flooding);
(c) The certification required by subdivision (B)(3)(c) of § 9-4.2007 of this article (elevation or flood proofing of nonresidential structures);
(d) The certification required by subdivision (B)(3)(d)1. or (B)(3)(d)2. of § 9-4.2007 of this article (wet flood proofing standards);
(e) The certified elevation required by division (B) of § 9-4.2010 of this article (subdivision standards); and
(f) The certification required by division (B) of § 9-4.2006 of this article (floodway encroachments);
(5) Make interpretations, where needed, as to the exact location of the boundaries of the areas of special flood hazard (for example, where there appears to be a conflict between a mapped boundary and actual field conditions). The person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation as provided in § 9-4.2012 of this article;
(6) Take action to remedy violations of this article;
(7) Base flood elevation changes due to physical alterations:
(a) Within six months information becoming available or project completion, whichever comes first, the Floodplain Administrator shall or assure that the permit applicant submits technical or scientific data to FEMA for a Letter of Map Revision (LOMR);
(b) All LOMR's for flood control projects are approved prior to the issuance of building permits must not be issued based on Conditional Letters of Map Revision (CLOMR's). Approved CLOMR's allow construction of the proposed flood control project and land preparation as specified in the "start of construction" definition; and
(c) Such submissions are necessary so that upon confirmation of those physical changes affecting flooding conditions, risk premium rates and floodplain management requirements are based on current data; and
(8) Changes in corporate boundaries. Notify FEMA in writing whenever the corporate boundaries have been modified by annexation or other means and include a copy of a map of the community clearly delineating the new corporate limits.
('66 Code, § 9-4.2005) (Ord. 708-C-S, passed 5-12-88; Am. Ord. 2025-C-S, passed 5-12-09)
(A) All uses shall meet the requirements, procedures, and specifications of the base zoning district and other provisions of this section.
(B) No new structure or facility shall cause an increase in flood elevation. This shall be certified by a registered professional engineer or surveyor. Such certification shall be provided to the Floodplain Administrator.
(C) No new structure shall be permitted in the FP-1 (Floodway) Combining District, except as specified as follows:
(1) Water wells and irrigation and drainage pumps and appurtenances;
(2) Fences, walls, signs, and other appurtenances provided they do not block potential floodwaters or create a debris catching obstacle to the passage of floodwaters, subject to the approval of the City Engineer;
(3) Marinas, including ramps, gas pumps, docks, and other structures, which must be located on, above, or immediately adjacent to a watercourse, may be located in the FP-1 (Floodway) Combining District provided there is no alternative to location in the FP-1 (Floodway) Combining District, and all feasible flood management measures are included as conditions of the site development plans;
(4) Public and private docks, wharves, piers, and boat launching ramps provided all reasonable measures to mitigate potential hazards are taken;
(5) Pilings and other support structures for marinas or approved uses accessory to marinas;
(6) Railroads, pipelines, utility lines, and public improvements, such as roads and streets, provided the passage of the 100-year flood is not impaired; and
(7) Bridges provided they have at least one foot clearance above the 100-year flood elevation.
(D) No cemeteries or expansions of existing cemeteries shall be permitted into designated floodways where structures or internments are proposed.
(E) No sanitary landfill shall be permitted.
(F) In the extraction of sand, gravel, and other materials, there shall be no stockpiling of materials, products, or overburden which may create an obstruc-tion to the passage of flood flows or increase the velocity or elevation of water within the floodway.
(G) Drainage and flood control development shall be permitted subject to the following conditions:
(1) The net effect of any drainage or flood control structure, facility, channel, or other project or combination of projects placed or enlarged within a floodway shall be such that it does not increase the area, velocity, or elevation of floodwaters within the floodway, unless such effect is a part of a flood control plan.
(2) The city shall condition the approval of any project so that no increase in flooding results.
PROJECTS, for the purpose of this division only, shall include, but not be limited to, the development of channel ponding areas or marsh.
(3) This section shall not preclude the maintenance and repair of existing flood protection projects.
(H) Accessory recreation structures, such as rest rooms, may be placed within the FP-1 (Floodway) Combining District where the design shall not affect the passage of the 100-year flood.
(I) Permitted uses in the FP-1 (Floodway) Combining District shall comply with the standards of construction specified in division (A) of § 9-4.2007 of this article, where applicable. Applicability shall be determined by the Floodplain Administrator.
('66 Code, § 9-4.2006) (Ord. 708-C-S, passed 5-12-88) Penalty, see §§ 1-2.01 et seq.
(A) All uses permitted in the base zoning district shall be permitted subject to the following exceptions, conditions, and standards pertaining to areas designated as both tidal and nontidal.
(B) In all areas of special flood hazard the following standards shall be 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 set forth in § 9-4.2011 of this article.
(2) Construction materials and methods.
(a) All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damages.
(b) All new construction and substantial improvements shall be constructed using methods and practices which minimize flood damages.
(c) All new construction and substantial improvements shall be constructed with electrical, heating, ventilation, plumbing, and air-conditioning equipment and other service facilities which are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
(d) Adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures shall be required within Zone AO.
(3) Elevation and floodproofing.
(a) New construction and the substantial improvement of any structure in Zone AE or Zone AH shall have the lowest floor, including the basement, elevated at least 12 inches above the base flood elevation. The depth number specified on the FIRM shall be used to determine the elevation of the base flood. Nonresidential structures may meet the standards set forth in subdivision (c) of this subdivision. Upon the completion of the structure, the elevation of the lowest floor, including the 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.
(b) New construction and the substantial improvement of any structure in Zone AO shall have the lowest floor, including the 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 set forth in subdivision (c) of this subdivision. Upon the completion of the structure, the elevation of the lowest floor, including the 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.
(c) Nonresidential construction shall either be elevated in conformance with subdivisions (a) or (b) of this subdivision or, together with attendant utility and sanitary facilities:
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 subdivision are satisfied. Such certification shall be provided to the Floodplain Administrator.
(d) For all new construction and substantial improvements, fully enclosed areas below the lowest floor which areas 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 shall either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria:
1. 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 the grade. Openings may be equipped with screens, louvers, valves, or other coverings or devices provided 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.
(e) Manufactured homes shall also meet the standards set forth in § 9-4.2011 of this article.
(4) Standards for recreational vehicles. All recreational vehicles placed in Zones A1-30, AH, and AE will either:
(a) Be on the site for fewer than 180 consecutive days;
(b) Be fully licensed and ready for highway use. A recreational vehicle is ready for highway use if it is on its wheels or jack system, is attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions; or
('66 Code, § 9-4.2007) (Ord. 708-C-S, passed 5-12-88; Am. Ord. 2025-C-S, passed 5-12-09)
Uses normally permitted within the existing zoning districts shall be permitted subject to the following restrictions, conditions, and standards applicable to tidal inundation:
(A) All buildings or structures shall be located landward above the mean higher high tide. The placement of manufactured homes shall be prohibited in tidal FP-2 areas.
(B) All buildings or structures shall be elevated so that the lowest supporting member is located no lower than the base flood elevation level, with all space below the lowest supporting member open so as not to impede the flow of water, except for breakaway walls. Compliance shall be certified by a registered professional engineer or architect.
(C) All buildings or structures shall be securely anchored on pilings or columns. Pilings or columns used as structural supports shall be designed and anchored so as to withstand all impact forces and buoyancy factors of the base flood. There shall be no fill used for structural support. Compliance shall be certified by a registered professional engineer or architect.
(D) Space below the lowest floor below the flood level shall include the following supplemental requirements:
(1) Any alteration, repair, reconstruction, or improvement to a structure started after December 12, 1980, shall not enclose the space below the lowest floor unless breakaway walls are used as provided for in this subdivision.
(2) Breakaway walls may be allowed below the base flood elevation provided they are not a part of the structural support of the building and are designed so as to breakaway, under abnormally high tides or wave action, without damage to the structural integrity of the building on which they are to be used.
(3) If breakaway walls are utilized, such enclosed space shall not be used for human habitation.
(4) Prior to construction, plans for any structure which will have breakaway walls shall be submitted to the Floodplain Administrator for approval.
('66 Code, § 9-4.2008) (Ord. 708-C-S, passed 5-12-88) Penalty, see §§ 1-2.01 et seq.
(A) All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate the infiltration of floodwaters into the system and the 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.
('66 Code, § 9-4.2009) (Ord. 708-C-S, passed 5-12-88) Penalty, see §§ 1-2.01 et seq.
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