Chapter 20.12
FLOOD HAZARD REDUCTION PROVISIONS
20.12.010 Construction standards—Generally.
20.12.020 Construction standards—Anchoring.
20.12.030 Construction standards—Materials and methods.
20.12.040 Construction standards—Elevation and floodproofing.
20.12.050 Standards for utilities.
20.12.060 Standards for subdivision.
20.12.070 Standards for manufactured homes.
20.12.075 Standards for recreational vehicles.
20.12.010 Construction standards—Generally.
In all areas of special flood hazards the standards set out in this chapter are required. (Ord. 1278 § 2 (part), 2002).
20.12.020 Construction standards—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 Section 20.12.070. (Ord. 1278 § 2 (part), 2002).
20.12.030 Construction standards—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.
(d) Require within Zone AH or AO adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures. (Ord. 1278 § 2 (part), 2002).
20.12.040 Construction standards—Elevation and floodproofing.
(a) New construction and substantial improvement of any structure, in zones other than AO, shall have the lowest floor, including basement, elevated to or above the base flood elevation. Nonresidential structures may meet the standards in subsection (c) 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, and verified by the community building inspector to be properly elevated. Such certification and verification shall be provided to the floodplain administrator.
(b) New construction and substantial improvement of any structure in Zone AO shall have the lowest floor, including basement, elevated above the highest adjacent grade at least as high as the depth number specified in feet on the FIRM, or at least two feet if no depth number is specified. Nonresidential structures may meet the standards in subsection (c) of this section. Upon the completion of the structure the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, or verified by the community building inspector to be properly elevated. Such certification and verification shall be provided to the floodplain administrator.
(c) Nonresidential construction shall either be elevated in conformance with subsection (a) or (b) of this section or together with attendant utility and sanitary facilities:
(1) Be floodproofed so that below the elevation recommended under subsections (a) and (b) of this section 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.
(d) Require, for all new construction and substantial improvements, 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) Either a minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers, valves or other coverings or devices; provided that they permit the automatic entry and exit of 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 in Section 20.12.070. (Ord. 1316 § 3(A), 2007; Ord. 1278 § 2 (part), 2002).
20.12.050 Standards for utilities.
(a) All new and replacement water supply and sanitary systems shall be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from systems into floodwaters.
(b) On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding. (Ord. 1278 § 2 (part), 2002).
20.12.060 Standards for subdivision.
(a) All new subdivision proposals and other proposed development, including proposals for manufactured home parks and subdivisions, greater than fifty lots or five acres, whichever is the lesser, shall:
(1) Identify the designated special flood hazard areas and base flood elevations, if available;
(2) Identify the elevations of lowest floors of all proposed structures and pads on the final plans;
(3) If the site is filled above the base flood elevation, the following as-built information for each structure shall be certified by a registered civil engineer or licensed land surveyor and provided as part of an application for a letter of map revision based on fill (LOMR-F) to the floodplain administrator:
(A) Lowest floor elevation;
(B) Pad elevation; and
(C) Lowest adjacent grade.
(b) All subdivision proposals and other proposed development shall be consistent with the need to minimize flood damage.
(c) All subdivision proposals and other proposed development shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.
(d) All subdivisions and other proposed development shall provide adequate drainage to reduce exposure to flood hazards. (Ord. 1316 § 3(B), 2007).
20.12.070 Standards for manufactured homes.
(a) All manufactured homes that are placed or substantially improved, within Zones A1—30, AH and AE on the community’s Flood Insurance Rate Map, on sites located:
(1) Outside of a manufactured home park or subdivision,
(2) In a new manufactured home park or subdivision,
(3) In an expansion to an existing manufactured home park or subdivision, or
(4) In an existing manufactured home park or subdivision on a site upon which a manufactured home has incurred "substantial damage" as the result of a flood,
shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to or above the base flood elevation and be securely fastened to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.
(b) All manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within Zones A1—30, AH, and AE on the community’s Flood Insurance Rate Map that are not subject to the provisions of subsection (a) of this section will be securely fastened to an adequately anchored foundation system to resist flotation, collapse, and lateral movement, and be elevated so that either the:
(1) Lowest floor of the manufactured home is at or above the base flood elevation, or
(2) Manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than thirty-six inches in height above grade.
Upon the completion of the structure, the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, and verified by the community building inspector to be properly elevated. Such certification and verification shall be provided to the floodplain administrator. (Ord. 1278 § 2 (part), 2002).
20.12.075 Standards for recreational vehicles.
All recreational vehicles placed on sites within Zones A1—30, AH, and AE on the community’s Flood Insurance Rate Map will either:
(a) Be on the site for fewer than one hundred eighty consecutive days, and be fully licensed and ready for highway use—a recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions, or
(b) Meet the permit requirements of Chapter 20.08 of this title and the elevation and anchoring requirements for manufactured homes in Section 20.12.070(a). (Ord. 1278 § 2 (part), 2002).
20.12.080 Floodways.
Located within areas of special flood hazard established in Section 20.04.070 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential, the following provisions apply:
(a) Until a regulatory floodway is adopted, no new construction, substantial development or other development (including fill) shall be permitted within Zones A1—30 and AE, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other development, will not increase the water surface elevation of the base flood more than one foot at any point within the city of Marysville.
(b) Prohibit encroachments, including fill, new construction, substantial improvements, and other development, unless certification by a registered professional engineer or architect is provided demonstrating that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge.
(c) If subsection (a) of this section is satisfied, all new construction and substantial improvements shall comply with all other applicable flood hazard reduction provisions of this chapter. (Ord. 1336 § 5, 2011: Ord. 1278 § 2 (part), 2002).