A. Standards Of Construction: The following provisions shall apply in all areas of special flood hazards:
1. Anchoring: All new construction and substantial improvements shall be anchored to the foundation to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. If a structure is elevated on fill as specified in subsections A2e and A3a of this section, the anchoring requirement shall be satisfied. Other alternative anchoring techniques that are effective may be considered.
2. Construction Materials And Methods:
a. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage. This would include, but not be limited to, water resistant lumber, floor coverings, adhesives, paints, masonry construction and finishes, waterproof electrical systems, and mechanical footings, or other acceptable materials measures. (See FEMA technical bulletin TB 2-93.)
b. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage. This would include, but not be limited to, elevating the structure, parallel alignment of structure with water flow, increase the structural designs to withstand hydrologic and hydrolographic sources, and increase depth of footings.
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. Adequate drainage paths are provided around structures on slopes to guide floodwaters around and away from proposed structures.
e. If fill is placed to elevate pads one foot (1') above base elevation, it must be demonstrated that fill will not settle and is protected from erosion, scour, or differential settlement, as follows:
(1) Fill shall be compacted to ninety five percent (95%) per ASTM (American Society For Testing And Materials) standard D-698.
(2) Fill slopes of granular material shall be no steeper than one-half foot (1/2') horizontal to one foot (1') vertical ratio unless substantiating data for steeper slopes is provided, and the slopes are approved by the town.
(3) If flow velocities are greater than five feet (5') per second, fill slopes shall be armored with stone or rock slope protection.
3. Elevation And Floodproofing:
a. New construction and substantial improvement of any residential structure shall include having the lowest floor (including basement), elevated to one foot (1') above base flood elevation or two feet (2') or more above the highest adjacent grade in the FP1 area, and it is recommended in the FP2 area to be one foot (1') above ground level. Upon completion of the structure, the elevation of the lowest floor (including basement) shall be certified by a registered professional engineer or licensed land surveyor, and verified by the building official to be properly elevated above the floodplain elevation at the time of certification. The certification or verification shall be provided to the floodplain administrator. In instances when the base flood elevation data has not been provided on the flood insurance rate map (FIRM), the provisions of this development code shall apply.
b. Nonresidential construction shall be either elevated in compliance with subsection A3a of this section or together with attendant utility and sanitary facilities and shall:
(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 subsection are satisfied. Such certifications shall be provided to the floodplain management administrator.
c. All new construction and substantial improvements to existing structures, shall include fully enclosed structural areas below the lowest floor that are subject to flooding, and the areas 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:
(1) Be certified by a registered professional engineer or an architect; or
(2) Provide a minimum of two (2) openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding. The bottom of all openings shall be no higher than one foot (1') 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
(3) Be verified by the floodplain administrator as complying with floodproofing standards approved by the federal insurance administration.
1. All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from systems into floodwaters.
2. On site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
3. All public utilities and facilities such as electrical, telephone, cable TV, gas, etc., shall utilize floodproofing measures in their location and construction to minimize flood damage.
C. Zoning Application Review Requirements:
1. All preliminary proposals shall identify the special flood hazard area and the elevation of the base flood.
2. All final plans shall provide the elevation of proposed structures and pads above the floodplain elevation as derived from the FEMA map adopted at the time of certification. If the site is filled above the base flood, the final pad elevation shall be certified by a registered professional engineer or licensed land surveyor and shall be submitted to the floodplain management administrator. The entire site need not be elevated; only the building pads need be elevated and other means of conducting storm flows through the site shall be provided.
3. All proposals shall be consistent with the need to minimize flood damage.
4. All proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.
5. All proposals shall provide adequate drainage to reduce exposure to flood hazards and not deflect flood flows onto other properties.
D. Manufactured Homes: All new and replacement manufactured homes and additions to manufactured homes shall comply with all applicable provisions of this section.
1. Nonresidential construction shall be elevated in compliance with subsection A3 of this section.
2. All manufactured homes shall be securely anchored to a permanent foundation system to resist flotation, collapse or lateral movement. Methods of anchoring shall include, but not be limited to, the use of over the top or frame ties to ground anchors.
E. Floodway Standards: Floodways are extremely hazardous areas due to the velocity of floodwaters that carry debris, potential projectiles, and erosion potential, therefore, the following provisions apply:
1. Encroachments, including fill, new construction, substantial improvements, stockpiling, and other development are prohibited 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.
2. If subsection E1 of this section is satisfied, all new construction and substantial improvements shall comply with all other applicable flood hazard reduction provisions of this section. (Ord. 253, 12-16-2014)