Town of Greenwich, NY
Washington County
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In all areas of special flood hazards the following standards are required:
A. 
Anchoring.
(1) 
All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure.
(2) 
All manufactured homes shall be installed using methods and practices which minimize flood damage. Manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement. Manufactured homes shall be elevated to or above the base flood elevation or two feet above the highest adjacent grade when no base flood elevation has been determined. Methods of anchoring may include, but are not to be limited to, use of over-the-top or frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces.
B. 
Construction materials and methods.
(1) 
All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
(2) 
All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
C. 
Utilities.
(1) 
Electrical, heating, ventilation, plumbing, air-conditioning equipment, and other service facilities shall be designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding. When designed for location below the base flood elevation, a professional engineer's or architect's certification is required;
(2) 
All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system;
(3) 
New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters; and
(4) 
On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
D. 
Subdivision proposals.[1]
(1) 
All subdivision proposals shall be consistent with the need to minimize flood damage;
(2) 
All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage;
(3) 
All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage; and
(4) 
Base flood elevation data shall be provided for subdivision proposals and other proposed developments (including proposals for manufactured home parks and subdivisions) greater than either 50 lots or five acres.
[1]
Editor's Note: See also Ch. 167, Subdivision of Land.
E. 
Encroachments.
(1) 
All proposed development in riverine situations where no flood elevation data is available (unnumbered A Zones) shall be analyzed to determine the effects on the flood-carrying capacity of the area of special flood hazards set forth in § 122-12A(3). This may require the submission of additional technical data to assist in the determination.
(2) 
In all areas of special flood hazard in which base flood elevation data is available pursuant to § 122-12B or § 122-13D(4) and no floodway has been determined, the cumulative effects of any proposed development, when combined with all other existing and anticipated development, shall not increase the water surface elevation of the base flood more than one foot at any point.
(3) 
In all areas of the special flood hazard where floodway data is provided or available pursuant to § 122-12B the requirements of § 122-15, Floodways, shall apply.
In all areas of special flood hazards where base flood elevation data has been provided as set forth in § 122-6, Basis for establishing areas of special flood hazards and § 122-12B, Use of other base flood data, the following standards are required:
A. 
Residential construction. New construction and substantial improvements of any resident structure shall:
(1) 
Have the lowest floor, including basement or cellar, elevated to or above the base flood elevation;
(2) 
Have fully enclosed areas below the lowest floor that are subject to flooding 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 licensed professional engineer or architect or meet or exceed the following minimum criteria:
(a) 
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;
(b) 
The bottom of all such openings shall be no higher than one foot above the lowest adjacent finished grade; and
(c) 
Openings may be equipped with louvers, valves, screens or other coverings or devices, provided they permit the automatic entry and exit of floodwaters.
B. 
Nonresidential construction. New construction and substantial improvements of any commercial, industrial or other nonresidential structure, together with attendant utility and sanitary facilities, shall either: have the lowest floor, including basement or cellar, elevated to or above the base flood elevation; or be floodproofed so that the structure is watertight below the base flood level with walls substantially impermeable to the passage of water. All structural components located below the base flood level must be capable of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy. The local administrator shall maintain on record a copy of all such certificates noted in this section.
(1) 
If the structure is to be elevated, fully enclosed areas below the base flood elevation shall be designed to automatically (without human intervention) allow for the entry and exit of floodwaters for the purpose of equalizing hydrostatic flood forces on exterior walls. Designs for meeting this requirement must either be certified by a licensed professional engineer or a licensed architect or meet the following criteria:
(a) 
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;
(b) 
The bottom of all such openings shall be no higher than one foot above the lowest adjacent finished grade; and
(c) 
Openings may be equipped with louvers, valves, screens or other coverings or devices, provided they permit the automatic entry and exit of floodwaters.
(2) 
If the structure is to be floodproofed:
(a) 
A licensed professional engineer or architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with accepted standards of practice to make the structure watertight with walls substantially impermeable to the passage of water, with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
(b) 
A licensed professional engineer or licensed land surveyor shall certify the specific elevation (in relation to mean sea level) to which the structure is floodproofed.
C. 
Construction standards for areas of special flood hazards without base flood elevations. New construction or substantial improvements of structures, including manufactured homes, shall have the lowest floor, including basement, elevated to or above the base flood elevation as may be determined in § 122-12B or two feet above the highest adjacent grade where no elevation data is available.
(1) 
New construction or substantial improvements of structures, including manufactured homes, shall have the lowest floor (including basement) elevated at least two feet above the highest adjacent grade next to the proposed foundation of the structure.
(2) 
Fully enclosed areas below the lowest floor that are subject to flooding shall be designed to automatically (without human intervention) allow for the entry and exit of floodwaters for the purpose of equalizing hydrostatic flood forces on exterior walls. Designs for meeting this requirement must either be certified by a licensed professional engineer or a licensed architect or meet the following criteria:
(a) 
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;
(b) 
The bottom of all such openings shall be no higher than one foot above the lowest adjacent finished grade;
(c) 
Openings may be equipped with louvers, valves, screens or other coverings or devices provided they permit the automatic entry and exit of floodwaters.
Located within areas of special flood hazard are areas designated as floodways. (See the definition of “floodway” in Article II, § 122-4). The floodway is an extremely hazardous area due to high-velocity floodwaters carrying debris and posing additional threats from potential erosion forces. When floodway data is available for a particular site as provided by §§ 122-6 and 122-12B, all encroachments, including fill, new construction, substantial improvements, and other development, are prohibited within the limits of the floodway unless a technical evaluation demonstrates that such encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge.