Town of Wilton, NH

Zoning Ordinance (2022)

10.0 Floodplain Conservation District

The regulations in the Town of Wilton Zoning Ordinance shall be considered part of the zoning Ordinance for purposes of administration and appeals under state law. If any provision of this ordinance differs or appears to conflict with any provision of the zoning Ordinance or other ordinance or regulation, the provision imposing the greater restriction or more stringent standard shall be controlling.

The following regulations shall apply to all lands designated as special flood hazard areas by the Federal Emergency Management Agency (FEMA) in its "Flood Insurance Study for the Town of Wilton, N.H." together with the associated Flood Insurance Rate Maps (FIRM) and Flood Boundary and Floodway Maps of the Town dated April 15, 1980, which are declared to be a part of this ordinance and are hereby incorporated by reference.

10.1 Definitions.

The following definitions shall apply only to this Floodplain Development Ordinance and shall not be affected by the provisions of any other ordinance of the Town of Wilton.

10.1.1

(Deleted) (March, 2007)

10.1.2 Area of Special Flood Hazard.

The land in the flood plain within the Town of Wilton subject to a 1 percent or greater chance of flooding in any given year. The area is designated as Zones A or AE on the Flood Insurance Rate Map. (Amended March, 2007)

10.1.3 Base Flood.

The flood level having a one-percent possibility of being equaled or exceeded in any given year.

10.1.4 Basement.

Any area of a building having its floor subgrade on all sides.

10.1.5 Building.

See "structure".

10.1.6 Breakaway Wall.

A wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces without causing damage to the elevated portion of the building or supporting foundation.

10.1.7 Development.

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 or storage of equipment or materials. (Amended March, 2007)

10.1.8 FEMA.

Federal Emergency Management Agency.

10.1.9 Flood or Flooding.

A general and temporary condition of partial or complete inundation of normally dry land areas from:

  1. The overflow of inland or tidal waters; and/or
  2. The unusual and rapid accumulation or runoff of surface waters from any source.

10.1.10

(Deleted) (March, 2007)

10.1.11 Flood Elevation Study.

An examination, evaluation and determination of flood hazards and if appropriate, corresponding water surface elevations, or an examination and determination of mud slide or flood related erosion hazards

10.1.12 Flood Insurance Rate Map

(FIRM) An official map incorporated with this ordinance on which FEMA has delineated both the special flood hazard areas and the risk premium zones applicable to the Town of Wilton. The FIRM will be used to make determinations of flood hazard zones and base flood elevations.

10.1.13 Flood Insurance Study.

See "Flood elevation study".

10.1.14 Floodplain or Flood-prone area.

Any land area susceptible to being inundated by water from any source (see "Flooding").

10.1.15 Flood proofing.

Any combination of structural and non-structural additions, changes, or adjustments to structures which reduce or eliminate flood damage to real estate or improved real property, water and sanitation facilities, structures and their contents.

10.1.16 Floodway.

see "Regulatory Floodway".

10.1.17 Functionally dependent use.

A use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. The term includes only docking and port facilities that are necessary for the loading/unloading of cargo or passengers, and ship building repair facilities but does not include long-term storage or related manufacturing facilities.

10.1.18 Highest adjacent grade.

The highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.

10.1.19 Historic Structure.

Any structure that is:

  1. listed individually in the National Register of Historic Places (a listing maintained by the Department of Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;
  2. certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;
  3. individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of the Interior; or
  4. individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either;
    1. By an approved state program as determined by the Secretary of the Interior, or
    2. Directly by the Secretary of the Interior in states without approved programs.

10.1.20 Lowest Floor.

The lowest floor of the lowest enclosed are (including basement). An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a basement area is not considered a building's lowest floor; provided, that such an enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirements of this ordinance.

10.1.21 Manufactured Home.

A structure, transportable in one or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when connected to the required utilities. For floodplain management purposes the term "manufactured home" includes park trailers, travel trailers, and other similar vehicles placed on site for greater than 180 consecutive days. This includes manufactured homes located in a manufactured home park or subdivision. (Amended March, 2007)

10.1.21.1 Manufactured Home Park or Subdivision.

A parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale. (Adopted March, 2007)

10.1.22 Mean sea level.

The National Geodetic Vertical Date (NGVD) of 1929 or other datum, to which base flood elevations shown on a community's FIRM are referenced.

10.1.22.1 New construction.

For the purposes of determining insurance rates, structures for which the “start of construction” commenced on or after the effective date of an initial FIRM or after December 31, 1974, whichever is later, and includes any subsequent improvements to such structures. For floodplain management purposes, new construction means structures for which the start of construction commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such structures. (Adopted March, 2007)

10.1.23 100-Year flood.

See "base flood".

10.1.24 Recreational Vehicle.

A vehicle which is (i) built on a single chassis; (ii) 400 square feet or less when measured at the largest horizontal projection; (iii)designed to be self propelled or permanently towable by a light duty truck; and (iv) designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel or seasonal use. (Amended March 1994.)

10.1.25 Regulatory Floodway.

The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height. (Amended March, 2007)

10.1.26 Special flood hazard area.

See "Area of Special Flood Hazard."

10.1.27 Structure.

For floodplain management purposes, a walled and roofed building, including a gas or liquid storage tank, that is principally above ground, as well as a manufactured home.

10.1.28 Start of Construction.

The date the building permit was issued, provided the actual start of construction, repair, reconstruction, placement, or other improvement was within 180 days of the permit date. The actual start means either the first placement of permanent construction of a structure on site, such as the pouring of a slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation; the placement of a manufactured home on a foundation; or any substantial improvement. Permanent construction does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; excavation for a basement, footings, piers, or foundations; the erection of temporary forms; or the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or part of the main structure.

10.1.29 Substantial damage.

Damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed 50 percent of the predamage market value of the structure.

10.1.30 Substantial Improvement.

Any combination of repairs, reconstruction, alteration, or improvements to a structure in which the cumulative cost equals or exceeds fifty percent of the market value of the structure. The market value of the structure should equal: (1) the appraised value prior to the start of the initial repair or improvement, or (2) in the case of damage, the value of the structure prior to the damage. 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. This term includes structures which have incurred substantial damage, regardless of actual repair work performed. The term does not include any project for improvement of a structure required to comply with existing health, sanitary, or safety code specifications which are solely necessary to assure safe living conditions or any alteration of a "historic structure:, provided that the alteration will not preclude the structure's continued designation as a "historic structure".

10.1.30.1 Violation.

The failure of a structure or other development to be fully compliant with the community’s flood plain management regulations. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required in 44CFR § 60.3(b)(5), (c)(4), (c)(10), (d)(3), (e)(2), (e)(4), or (e)(5) is presumed to be in violation until such time as that documentation is provided. (Adopted March, 2007)

10.1.31 Water surface elevation.

The height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929, (or other datum, where specified) of floods of various magnitudes and frequencies in the floodplains.

10.2 Permit Required.

All proposed development in any special flood hazard area shall require a permit. The building inspector shall review all building permit applications for new construction or substantial improvements to determine whether proposed building sites will be reasonably safe from flooding.

The Building Inspector will not issue a building permit until the applicant certifies that all necessary permits have been received from those governmental agencies from which approval is required by federal or state law, including Section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 U.S.C. 1334. It shall be the responsibility of the applicant to certify these assurances to the Building Inspector.

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

  1. the as-built elevation (in relation to NGVD) of the lowest floor (including the basement) and include whether or not the structure contains a basement;
  2. if the structure has been floodproofed, the as-built elevation (in relation to NGVD) 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 the 100-Year Flood Elevation.

In special flood hazard areas the Building Inspector shall determine the 100-year 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; (Amended March, 2007)
  2. in unnumbered A zones the Building Inspector shall obtain, review, and reasonably utilize any 100-year flood elevation data available from any federal, state, or other source including data submitted to the Town for development proposals (i.e. subdivisions, site approvals).

10.4 Construction Standards.

  1. All new construction or substantial improvements within a flood prone area 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 conditions of flooding.
  2. Any new construction or substantial improvement within the A and AE Zones shall meet the following criteria that: (Amended March, 2007)
    1. all new construction or substantial improvement of residential structures have the lowest floor (including the basement) elevated to or above the 100-year flood elevation;
    2. all new construction or substantial improvement of non-residential structures have the lowest floor (including the basement) elevated to or above the 100-year flood level; or together with attendant utility and sanitary facilities, shall:
      1. be floodproofed so that below the 100-year flood elevation the structure is watertight will 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 for meeting the provisions of this section;
  3. all manufactured homes to be placed or substantially improved within special flood hazard areas shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is at or above the base flood level 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 AE shall either: (i) be on the site for fewer than 120 consecutive days; (ii) be fully licensed and ready for highway use; or (iii) meet all standards of Section 60.0 (b) (1) of the National Flood Insurance Program Regulations and the elevation and anchoring requirements for manufactured homes in Paragraph (c) (6) of Section 60.3. (Amended March 1994.) (Amended March, 2007)
  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 of storage;
    2. the area is not a basement;
    3. the area shall be designed to automatically equalize hydrostatic flood forces or 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. 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 floodprone areas the applicant shall provide the Building Inspector with assurance that these systems will be designed to minimize or eliminate infiltration of flood waters into the systems and discharges from the systems into flood waters, and that on-site waste disposal systems will be located to avoid impairment to them or contamination from them during periods of flooding.

10.5 Alteration of Water Courses.

Any development involving the alteration of a watercourse shall meet the following requirements.

  1. Prior to the alteration or relocation of a watercourse the applicant for such authorization shall notify the Wetlands Bureau of the New Hampshire Department of Environmental Services and submit copies of such notification to the Building Inspector, in addition to the copies required by RSA 483-A:3. Further, the applicant shall be required to submit copies of said notification to those adjacent communities as determined by the Building Inspector. (Amended March 2000) (Amended March 2007)
  2. The applicant shall submit to the Building Inspector, certification provided 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 designated 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 community during the base flood discharge. (Amended March, 2007)
  4. Until a Regulatory Floodway is designated along watercourses, no new construction, substantial improvements or other development (including fill) shall be permitted within Zone AE on the FIRM, 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 community. (Amended March, 2007)

  5. The Building Inspector shall obtain, review, and reasonably utilize any floodway data available from Federal, State, or other sources as criteria for requiring that all development located in Zone A meet the following floodway requirement:

    "No encroachments, including fill, new construction, substantial improvements, and other development are allowed within the floodway that would result in any increase in flood levels within the community during the base flood discharge." (Adopted March, 2007)

10.6 Variances and Appeals.

Any order, requirement, decision or determination of the Building Inspector made under this ordinance may be appealed to the Zoning Board of Adjustment as set forth in RSA 676:5.

If the applicant, upon appeal, requests a variance as authorized by RSA 674:33, I (b), in addition to the usual variance standards under state law the applicant shall show that:

  1. the variance will not result in increased flood heights, additional threats to public safety or extraordinary public expense;
  2. if the requested variance is for activity within a designated regulatory floodway, it will not result in any increase in flood levels during the base discharge; and
  3. considering flood hazard, the variance is necessary to afford relief.

The Zoning Board of Adjustment shall notify the applicant in writing that:

  1. the issuance of a variance to construct below the base flood level will result in increased premium rates for flood insurance up to amounts as high as $25 for $100 of insurance coverage; and
  2. construction below the bases flood level increases risks to life and property.

The notification shall be maintained with a record of all variance actions.

The Town 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.