Manhattan Beach Municipal Code Ch. 9.76 Flood Plain Management Regulations

Unless specifically defined below, words or phrases used in this chapter shall be interpreted so as to give them the same meaning as they have in common usage and so as to give this chapter its most reasonable application.

A. "Development" means any man-made change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging filling, grading, paving, excavation or drilling operations.

B. "Flood" means a temporary rise in stream's flow or stage that results in water overflowing its banks and inundating areas adjacent to the channel or an unusual and rapid accumulation of runoff or surface waters from any source.

C. "Floodproofing" means any combination of structural and non-structural additions, changes, or adjustments to structures, including utility and sanitary facilities, which would preclude the entry of water. Structural components shall have the capability of resisting hydrostatic and hydrodynamic loads and the affect of buoyancy.

D. "Mobile home" means a structure, transportable in one or more sections, which is built on a permanent basis and designed to be used with or without a permanent foundation when connected to the required utilities. It does not include recreational vehicles or travel trailers.

E. "Regulator flood elevation" means the water surface elevation of the one hundred (100) year flood.

F. "Substantial improvement" means any repair, reconstruction or improvement of a structure, the cost of which equals or exceeds fifty (50) percent of the market value of the structure either (a) before the improvement is started, or (b) if the structure has been damaged and is being restored before the damage occurred. For the purposes of this definition "substantial improvement" is considered to occur when the first alteration of any wall, ceiling, floor or other structural part of the building commences whether or not that alteration affects the external dimensions of the structure. The term does not, however, include any alteration to comply with existing State or local health, sanitary, building or safety codes or regulations.

G. "One hundred (100) year flood" means the condition of flooding having one percent (1%) chance of annual occurrence.

The City shall review all development permit applications to determine if the site of the proposed development is reasonably safe from flooding and that all necessary permits have been received as required by Federal, State, local or other applicable ordinance.

The City, in reviewing all applications for new construction, substantial improvements, prefabricated buildings, placement of mobile homes and other developments will:

A. Obtain, review and reasonably utilize, if available, any regulatory flood elevation data from Federal, State or other sources; and require within areas subject to flooding that the following performance standards be met:

1. The first-floor elevation (to include basement) of new residential structures, be elevated to or above the regulatory flood elevation.

2. The first-floor elevation (to include basement of non-residential structures) be elevated or floodproofed to or above the regulatory flood elevation.

B. Require the use of construction materials and utility equipment that are resistant to flood damage.

C. Require the use of construction methods and practices that will minimize flood damage.

D. Require engineering and architectural design which is adequate to prevent the flotation, collapse or lateral movement of the structure or portions of the structure due to flooding.

E. Assure that in regard to mobile homes, specified anchoring requirements are met including but not limited to:

1. Over-the-top ties be provided at each of the four corners of the mobile home with two additional ties per side at the intermediate locations and mobile homes less than fifty (50) feet long requiring one additional tie per side.

2. Frame ties be provided at each corner of the home with five (5) additional ties per side at intermediate points and mobile homes less than fifty (50) feet long requiring four (4) additional ties per side.

3. All components of the anchoring system be capable of carrying a force of four thousand eight hundred (4,800) pounds.

4. Any additions to mobile homes be similarly anchored.

The City shall review all subdivision and parcel map applications and shall make findings of fact which assure that:

A. Proposed developments are consistent with the need to minimize flood damage.

B. Subdivision proposals and other proposed new development greater than five (5) acres or fifty (50) lots, whichever is lesser, include within such proposals regulatory flood elevation data in areas subject to flooding.

C. Adequate drainage is provided so as to reduce exposure to flood hazards.

D. All public utilities and facilities are located so as to minimize or eliminate flood damage.

New and replacement water and sewerage systems shall be constructed to eliminate or minimize infiltration by, or discharge into floodwaters. On-site waste disposal systems will be designed to avoid impairment or contamination during flooding.

The City will insure that the flood carrying capacity within the altered or relocated portion of any watercourse is maintained. The City will notify, in riverine situations, adjacent communities and the State Coordinating Office prior to any alternation or relocation of a watercourse, and submit copies of such notifications to the Federal Insurance Administrator.

(§ 1, Ord. 1521, eff. March 9, 1978)

Plans, construction, and operation of facilities requiring building permits shall be in conformance with the "standard union storm water mitigation plan" for the City as adopted by Section 5.84.100 of this Code.

(§ 3, Ord. 2017, eff. October 19, 2000)