10.0 Floodplain Conservation District

This Chapter 10, “Floodplain Conservation District,” is the “Floodplain Development Ordinance” for the Town of Wilton, NH. It is intended to be read in conjunction with the remainder of the Wilton Zoning Ordinance (Zoning Ordinance) for purposes of administration and appeals under State law. If any provision of this Chapter differs from or appears to conflict with any other provision of the Zoning Ordinance or any other ordinance or regulation, the provision imposing the stricter requirement or standard shall be controlling.

The following regulations shall apply to all lands designated as areas of special flood hazard by the Federal Emergency Management Agency (FEMA) in its Flood Insurance Study for the County of Hillsborough, N.H." dated September 25, 2009, as it may from time to time be amended, together with the associated Flood Insurance Rate Maps (FIRM) dated September 25, 2009, as they may from time to time be amended, which are declared to be a part of this ordinance and are hereby incorporated by reference.

10.1 Definitions.

Words and phrases defined below have the meanings in this section when they are used in this Chapter 10. Definitions in this section are not applicable outside of this Chapter unless they are accompanied by an explicit reference to this Chapter. Definitions in Chapter 3 of the Zoning Ordinance are applicable in this Chapter unless they conflict with a definition in this Chapter, in which case the definition on this section shall apply.

10.2 Permit Required.

All proposed development in any Area of Special Flood Hazard shall require a permit from the Building Inspector, who shall review all requests for development as well as all building permit applications for new construction or substantial improvements to determine whether the sites of proposed development, substantial improvements, or new construction will be reasonably safe from flooding and compliant with the terms of this Chapter.

The Building Inspector will not issue a building permit or approve other development in any Area of Special Flood Hazard until the applicant certifies and provides reasonable proof that all necessary permits have been received from those governmental agencies whose approval is required by federal or state law, including, without limitation, Section 404 of the Federal Water Pollution Control Act of 1972, 33 U.S.C. 1334.

In addition, the applicant shall supply the Building Inspector with the following information for all proposed new or substantially improved structures:

1. The as-built elevation (in relation to mean sea level) of the lowest floor and whether or not the structure contains a basement;
2. If the structure has been floodproofed, the as-built elevation (in relation to mean sea level) to which the structure was floodproofed; and
3. Any certification of floodproofing.

The Building Inspector shall maintain this information for public inspection and furnish it upon request.

10.3 Location of Base Flood Elevation.

In Areas of Special Flood Hazard, the Building Inspector shall determine the Base Flood Elevation in the following order of precedence according to the data available:

1. In Zone AE, refer to the elevation data provided in the communities Flood Insurance Study and accompanying FIRM;
2. In Zone A, the Building Inspector may obtain, review and reasonably utilize any Base Flood Elevation data available from any federal, state, or other source including data submitted to the Town for development proposals (e.g., subdivisions, site plan approvals) by a qualified engineer, architect or surveyor. Where the Building Inspector determines that a Base Flood Elevation is not reasonably available or ascertainable for Zone A, the Base Flood Elevation shall be determined to be at least two feet above the highest adjacent grade.

10.4 Construction Standards.

1. All new construction or substantial improvements within an Area of Special Flood Hazard shall be:
   1. Designed (or modified) and adequately anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;
   2. Constructed with materials resistant to flood damage;
   3. Constructed by methods and practices that minimize flood damages; and
   4. Constructed with electrical, heating, ventilation, plumbing, 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 flooding.
2. Any new construction or substantial improvement within the A and AE Zones shall meet the following requirements:
   1. For residential structures, the lowest horizontal structural member of the lowest floor shall be elevated to or above the Base Flood Elevation;
   2. For non-residential structures, the lowest horizontal structural member of the lowest floor shall be elevated to or above the Base Flood Elevation or, together with attendant utility and sanitary facilities, shall:
      1. Be floodproofed so that areas below the Base Flood Elevation the structure are watertight with walls substantially impermeable to the passage of water;
      2. Have structural components capable of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy; and
      3. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice to meet the provisions of this section;
3. All manufactured homes to be placed or substantially improved within an Area of Special Flood Hazard shall be elevated on permanent foundations such that the lowest floor of the manufactured home is at or above the Base Flood Elevation and securely anchored to resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not 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.
4. Recreational vehicles placed on sites within Zone A or AE shall either: (1) (i) be on the site for fewer than 120 consecutive days and (ii) be fully licensed and on wheels or jacking systems, attached to the site only by quick disconnect type utilities and security devices, with no permanently attached additions; or (2) meet all standards of this Chapter and the elevation and anchoring requirements for manufactured homes in paragraph (c) above.
5. For all new construction and substantial improvements, fully enclosed areas below the lowest floor that are subject to flooding are permitted provided they meet the following requirements:
   1. The enclosed area is unfinished or flood resistant, usable solely for the parking of vehicles, building access or storage;
   2. The area is not a basement;
   3. The area is designed to automatically equalize hydrostatic flood forces or exterior walls by allowing for the entry and exit of floodwaters, either as certified by a registered professional engineer or architect or meet or by exceeding the following minimum requirements:
      1. 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;
      2. The bottom of all openings shall be no higher than one foot above grade; and
      3. Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters; and
6. Where new or replacement water and sewer systems (including on-site systems) are proposed in Areas of Special Flood Hazard the applicant shall provide the Building Inspector with assurance that these systems will be designed to minimize or eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters, and that on-site waste disposal systems will be located to avoid impairment to them or contamination from them during flooding.

10.5 Alteration of Water Courses.

Any proposed development involving the alteration of a watercourse shall be noticed and authorized as follows, and shall otherwise meet the following requirements, which shall be in addition to all other requirements and limitations in the Zoning Ordinance:

1. The applicant proposing such alteration shall notify the Wetlands Bureau of the New Hampshire Department of Environmental Services (Wetlands Bureau) and submit copies of such notification, including notice of all scheduled hearings before the Wetlands Bureau, (1) to the Building Inspector, (2) as required by RSA 482-A:3 and (3) to those adjacent communities identified by the Building Inspector.
2. The applicant shall submit to the Building Inspector a certification prepared, signed, and stamped by a registered professional engineer assuring that the flood-carrying capacity of an altered or relocated watercourse can and will be maintained.
3. Along watercourses with a Regulatory Floodway, no encroachments, including fill, new construction, substantial improvements, and other development, are allowed within the floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practices that the proposed encroachment would not result in any increase in flood levels within the Town of Wilton or any adjacent community during the base flood discharge.
4. If there is no Regulatory Floodway along a watercourse or portion thereof, no new construction, substantial improvements or other development (including fill) shall be permitted within Zone AE on the FIRM along that watercourse unless it is demonstrated by the applicant that the cumulative effect of the proposed development, when combined with all existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the Town of Wilton or any adjacent community.
5. Based on review and reasonable utilization of floodway data available from Federal, state or other sources, the Building Inspector shall determine that no encroachments, including dredge, fill, topographical alterations, new construction, substantial improvements or other development located in Zone A could result in any increase in flood levels within the community during the base flood discharge.

10.6 Variances and Appeals.

1. Any order, requirement, decision or determination of the Building Inspector that interprets, applies, or construes this Chapter may be appealed to the Zoning Board of Adjustment as set forth in RSA 676:5.
2. If the applicant, upon appeal, requests a variance as authorized by RSA 674:33, I, in addition to the variance standards set forth in RSA 674:33, I (b), the Zoning Board of Adjustment shall only grant a variance upon a finding that the grant of a variance satisfies the requirements of 44 C.F.R. § 60.6(a), as amended, which includes finding that:
   1. For variances for developments, new construction, or substantial improvements within any designated regulatory floodway there will be no increase in flood levels during the base flood discharge;
   2. For variances for new construction and substantial improvements to be erected on a lot of one-half acre or less in size contiguous to and surrounded by lots with existing structures constructed below the base flood level;
   3. The applicant has proved that:
      1. good and sufficient cause exists for the grant of the variance;
      2. failure to grant the variance would result in exceptional hardship to the applicant; and
      3. the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, or create nuisances, cause fraud on or victimization of the public, or conflict with existing local laws or ordinances;
   4. The variance is the minimum necessary, considering the flood hazard, to afford relief;
3. If the ZBA grants the variance, it shall notify the applicant in writing that:
   1. The issuance of a variance to construct below the base flood level will result in substantially increased premium rates for flood insurance as high as $25 for $100 of insurance coverage; and
   2. Such construction below the base flood level will increase risks to life and property.
   Such notification shall be maintained with a record of all variance actions.
4. The Town of Wilton shall maintain a record of all variance actions, including the justification for their issuance, and report the issuance of any variance to the FEMA’s Federal Insurance Administrator in its annual or biennial report.