Dover City Zoning Code
ARTICLE VII
Floodplain Development
§ 170-25 General provisions.
[Amended 8-22-2018 by Ord. No. 2018.08.08-009; 9-11-2019 by Ord. No. 2019.08.28-012; 7-22-2020 by Ord. No. 2020.07.08-006]
A.
Authority. These rules and regulations are adopted by the City of Dover pursuant of the authority granted by RSA 674:16.
B.
Conflict and severability. If any provision of this article differs or appears to conflict with any other provision of this chapter or other ordinance or regulation, the provision imposing the greater restriction or more stringent standard shall be controlling. Should any provision of this article be declared unconstitutional or invalid by a court of competent jurisdiction, such decision shall not affect the validity of this section as a whole or any part thereof other than the part so declared to be unconstitutional or invalid.
C.
Purpose. Certain areas of the City of Dover are subject to periodic flooding, causing serious damage to properties within these areas. Relief is available in the form of flood insurance as authorized by the National Flood Insurance Act of 1968.[1] Therefore, the City of Dover has chosen to become a participating community in the National Flood Insurance Program and agrees to comply with the requirements of the National Flood Insurance Act of 1968 (PL 90-488, as amended) as detailed in this article. The City of Dover recognizes the need to minimize the potential loss of life and property during periods of flooding by regulating the alteration and/or the development of those areas of special flood hazard identified by FEMA. The following regulations shall apply to all lands designated as areas of special flood hazard by FEMA in its Flood Insurance Study for the County of Strafford, New Hampshire, dated September 30, 2015, together with the following associated Flood Insurance Rate Map panel numbers for the City of Dover: 33017CO218E, 33017CO302E, 33017CO305E, 33017CO310E, 33017CO320E, 33017CO330E, 33017CO340E, and 33017CO0405E, dated September 30, 2015, which are declared to be a part of this chapter and are hereby incorporated by reference. The Flood Insurance Study is on file at the Department of Planning and Community Development.
[1]
Editor's Note: See 42 U.S.C. § 4001 et seq.
D. AREA OF SHALLOW FLOODING AREA OF SPECIAL FLOOD HAZARD BASE FLOOD BASE FLOOD ELEVATION BASEMENT BUILDING CRITICAL FACILITIES DEVELOPMENT FEMA FLOOD or FLOODING FLOOD INSURANCE RATE MAP (FIRM) FLOOD INSURANCE STUDY (FIS) FLOODPLAIN FLOODPROOFING or FLOODPROOFED FREEBOARD HIGHEST ADJACENT GRADE HISTORIC STRUCTURE LOWEST FLOOR MANUFACTURED HOME MANUFACTURED HOME PARK or MANUFACTURED HOME SUBDIVISION MEAN SEA LEVEL NEW CONSTRUCTION RECREATIONAL VEHICLE REGULATORY FLOODWAY RIVERINE START OF CONSTRUCTION STRUCTURE SUBSTANTIAL DAMAGE SUBSTANTIAL IMPROVEMENT or SUBSTANTIALLY IMPROVED(1) (2) UNSUITABLE DEVELOPMENT AREA VIOLATION WATER SURFACE ELEVATION
Definitions. As used in this section, the following terms mean:
A designated AO Zone on the FIRM with a one-percent or greater annual possibility of flooding to an average depth of one to three feet where a clearly defined channel does not exist, where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow.
The land in the floodplain within the City of Dover subject to a one-percent or greater annual possibility of flooding in any given year. The area is designated on the FIRM as Zones A, AO, and AE.
The flood having a one-percent chance of being equaled or exceeded in any given year.
The water surface elevation having a one-percent chance of being equaled or exceeded in any given year as defined on the Flood Insurance Rate Map (FIRM) currently in effect and the Flood Insurance Study (FIS) report.
[Amended 10-13-2021 by Ord. No. 2021.09.08-006]
Any area of a building having its floor subgrade on all sides.
"Structure" as defined in this subsection.
Facilities that are vital to public health and safety, including police stations, fire and rescue facilities, hospitals, shelters, schools, nursing homes, and water supply and waste treatment facilities.
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
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.
Federal Emergency Management Agency.
A general and temporary condition of partial or complete inundation of normally dry land areas from the overflow of inland or tidal waters, or the unusual and rapid accumulation or runoff of surface waters from any source.
An official map incorporated within this chapter on which FEMA has delineated both the areas of special flood hazard and the risk premium zones that are applicable to the City of Dover.
An examination, evaluation and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation and determination of mudslide (i.e. mudflow) and/or flood-related erosion hazards.
Any land area which is susceptible to being inundated by water from any source. (See definition of "flooding.")
Any combination of structural and nonstructural 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.
An additional amount of height above the base flood elevation used as a factor of safety in determining the level at which a structure's lowest floor must be elevated or floodproofed.
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
The highest natural elevation of the ground surface, prior to construction, next to the proposed walls of a structure.
Any structure that is listed individually in the National Register of Historic Places (maintained by the Department of the Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register; certified or preliminarily determined by the Secretary as contributing to the historic significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district; or individually listed on a local inventory of historic places, provided the local historic preservation program has been certified by either the appropriate state or federal program.
The lowest floor of the lowest enclosed area (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 nonelevation design requirements set forth herein.
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. "Manufactured home" also includes park trailers, travel trailers and other similar vehicles placed on a site greater than 180 days. This includes manufactured homes located in a manufactured home park or manufactured home subdivision.
A parcel or contiguous parcels of land divided into two or more manufactured home lots for rent or sale.
The National Geodetic Vertical Datum (NGVD) of 1929, North American Vertical Datum (NAVD) of 1988, or other datum to which base flood elevations shown on a community's Flood Insurance Rate Map (FIRM) are referenced.
Structures for which the start of construction commenced on or after April 9, 1980, and includes any subsequent improvements to such structures.
A vehicle which is built on a single chassis; 400 square feet or less when measured at the largest horizontal projection; designed to be self-propelled or permanently towable by a light-duty truck; and designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.
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 increasing the water surface elevation more than a designated height.
Relating to, formed by or resembling a river, including tributaries, stream, brook, etc.
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. "Start of construction" includes substantial improvements. The actual start means either the first placement of permanent construction of a structure on site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation, or the placement of manufactured home on a foundation. Permanent construction does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footing, piers, or foundations or the erection of temporary forms; nor does it include the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or part of the main structure.
A walled and roofed building, including a gas or liquid storage tank that is principally above ground, as well as a manufactured home.
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% of the market value of the structure before the damage occurred.
Any reconstruction, rehabilitation, or other improvement to a structure, taking place during a five-year period, in which the cumulative cost equals or exceeds 50% of market value of the structure before the start of construction of the improvement. The period of accumulation begins when the first improvement of the structure is permitted subsequent to September 1, 2021. This term includes structures that have incurred substantial damage, regardless of actual repair work performed. The term does not, however, include either:
[Amended 10-13-2021 by Ord. No. 2021.09.08-006]
Any project for improvement of a structure to correct existing violations of state or local health, sanitary or safety code specifications which have been identified by the Building Official, and which are the minimum necessary to assure safe living conditions; or
Any alteration of a structure listed on the National Register of Historic Places or a state inventory of historic places, provided that the alteration will not preclude the structure's continued designation as an historic structure.
The area of a site that includes wetlands, water bodies, slopes exceeding a grade of 20% and totaling more than 2,000 square feet of contiguous area, land used for septic systems, floodways, and floodway fringe within the 100-year floodplain as shown on the latest FEMA maps accepted by the City, and public utility easements.
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
The failure of a structure or other development to be fully compliant with this section. A structure or other development without an elevation certificate, other certifications, or other evidence of compliance required herein is presumed to be in violation until such time as that documentation is provided.
The height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929, North American Vertical Datum (NAVD) of 1988, or other datum, where specified, of floods of various magnitudes and frequencies in the floodplains.
E.
Development review.
(1)
All proposed development in any area of special flood hazard shall require a permit. Prior to the issuance of a building permit by the Building Official, whether for new construction (manufactured homes included) or the substantial improvement thereon, the Department of Planning and Community Development shall determine whether said project site is located in an area of special flood hazard. If said project site is so located, wholly or in part, in an area of special flood hazard, then compliance with the rules and regulations contained herein shall be required.
(2)
Prior to the granting of subdivision approval, the Zoning Administrator shall determine whether the property is located within an area of special flood hazard, and, if so situated, compliance with the rules and regulations contained herein shall be required.
(3)
Prior to the granting of site review approval, the Zoning Administrator shall determine whether said site is located within an area of special flood hazard, and, if so situated, compliance with the rules and regulations contained herein shall be required.
(4)
Duties and responsibilities of the Zoning Administrator concerning development review shall include, but are not limited to:
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
(a)
Ensure compliance with the rules and regulations contained herein.
(b)
Ensure prior to any alteration or relocation of a watercourse that the required submittal and notification requirements in this section are met.
(c)
Ensure the administrative and enforcement procedures detailed in RSA 676 are followed for any violations of this section.
(5)
For all development in an area of special flood area that proposes to improve an existing structure, including alterations, movement, enlargement, replacement, repair, additions, rehabilitations, renovations, repairs of damage from any origin (such as, but not limited to, flood, fire, wind or snow) and any other improvement of or work on such structure, including within its existing footprint, the Zoning Administrator shall consult with the Building Official who shall determine if the proposed work constitutes substantial improvement or repair of substantial damage as defined herein. This determination requires evaluation of previous permits issued for improvements and repairs as specified in the definition of "substantial improvement." If the applicant disagrees with the Building Official's substantial improvement or repair of substantial damage determination, it may appeal said determination to the Zoning Board of Adjustment per § 170-59D.
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
F.
Required data. Applications for development shall include the following:
(1)
Plans in duplicate, drawn to scale, showing the nature, location, dimensions and elevations of the area in question; existing or proposed structures; fill, storage of materials and drainage facilities; and the location of the foregoing. Specifically, the following information is required where appropriate:
(2)
Permit review. The Department of Planning and Community Development shall:
(a)
Review all development permits to determine that the requirements of this section have been satisfied.
(b)
Review all development permits to determine 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 Department of Planning and Community Development.
(c)
The Department of Planning and Community Development shall review all development permits to determine if the proposed development adversely affects the flood-carrying capacity of the areas of special flood hazard. For purposes of this section, "adversely affects" means that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the base flood elevation more than one foot at any point within the City of Dover.
G.
Information to be obtained and maintained.
(1)
The Department of Planning and Community Development shall maintain and record for public inspection the certification of floodproofing required in Subsection K(2) and a certified FEMA elevation certificate with the as-built elevation, in relation to mean sea level, of the lowest floor, including the basement, of all new or substantially improved structures and shall include whether or not such structures contain a basement and, if the structure has been floodproofed, the as-built elevation, in relation to mean sea level, to which the structure was floodproofed. This information must be furnished by the applicant.
(2)
In areas of special flood hazard, the Department of Planning and Community Development shall determine the base flood elevation in the following order of precedence according to the data available:
(a)
In Zone AE, refer to the elevation data provided in the community's Flood Insurance Study and accompanying FIRM.
(b)
In Zone A, the Building Official shall obtain, review and reasonably utilize any base flood elevation data available from any federal, state or other source, including data submitted for development proposals (i.e., subdivisions, site review plans, etc.) to the community.
(c)
In Zone A, where the base flood elevation is not available, the base flood elevation shall be at least two feet above the highest adjacent grade.
(d)
In Zone AO, the base flood elevation is determined by adding the elevation of the highest adjacent grade to the depth number specified on the FIRM or, if no depth number is specified on the FIRM, at least two feet.
(3)
The Department of Planning and Community Development shall maintain for public inspection all records pertaining to the provisions of this article.
H.
Alteration of watercourses.
(1)
In riverine situations, 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 Planning Board in the form of a conditional use permit application, in addition to the copies required by RSA 482-A:3. Further, the applicant shall be required to submit copies of said notification to those adjacent communities as determined by the Department of Planning and Community Development, including notice of all scheduled hearings before the Wetlands Bureau and notice of scheduled hearings before the Planning Board for conditional use permits as required by § 170-27, Conservation District, and § 170-28, Wetland Protection District.
(2)
The applicant shall submit to the Planning Board, in the form of a conditional use permit application, certification provided by a professional engineer assuring that the flood-carrying capacity of an altered or relocated watercourse can and will be maintained.
I.
Interpretation of boundaries.
(1)
The Department of Planning and Community Development shall make interpretations, where needed, as to the exact location of the boundaries of the area of special flood hazard in a construction proposal; for example, where there appears to be a conflict between a mapped boundary and actual field conditions. To assist in this determination, the applicant may be required to submit an accurate site plan showing flooding relationships, including elevations.
(2)
To determine accurately if a structure is located in an area of special flood hazard, the owner or applicant may hire a licensed land surveyor or certified engineer to measure the distance from a physical feature on the FIRM to the structure's location.
(3)
The structure is considered borderline if it is located within 100 feet of a boundary. A certified engineer shall compare the base flood elevation and the lowest ground elevation at the borderline structure's location to determine if the structure is in or out of the area of special flood hazard. If the engineer certifies the structure as out of the area of special flood hazard, but the Planning and Community Development Department or Community Services Department has historic or other data that confirms the property is prone to flooding, the Planning and Community Development Department may request a letter of map amendment (LOMA) from FEMA.
J.
General standards. In all areas of special flood hazard, the following standards are required:
(1)
Anchoring.
(a)
All new construction and substantial improvements shall be 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.
(b)
All manufactured homes to be placed or substantially improved within areas of special flood hazard shall be elevated on a permanent foundation, such that the lowest floor of the manufactured home is at least two feet above the base flood elevation, and shall be securely anchored to resist flotation, collapse or lateral movement by providing over-the-top or frame ties to ground anchors. Specific requirements shall be that:
[1]
Over-the-top ties shall be provided at each of the four corners of the manufactured home, with two additional ties per side at intermediate locations, with manufactured homes less than 50 feet long requiring one additional tie per side, or frame ties shall be provided at each corner of the home, with five additional ties per side at intermediate points, with manufactured homes less than 50 feet long requiring four additional ties per side.
[2]
All components of the anchoring system shall be capable of carrying a force of 4,800 pounds.
[3]
Any additions to the manufactured home shall be similarly anchored.
(2)
Construction materials and methods.
(a)
All new construction and substantial improvements shall be constructed with materials resistant to flood damage.
(b)
All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
(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 elevated at least two feet above the base flood elevation so as to prevent water from entering or accumulating within the components during conditions of flooding.
[Amended 10-13-2021 by Ord. No. 2021.09.08-006]
(3)
Utilities and storage.
[Amended 10-13-2021 by Ord. No. 2021.09.08-006]
(a)
The applicant shall provide the Department of Planning and Community Development with assurance that all new and replacement water supply systems, including on-site systems, shall be designed to minimize or eliminate infiltration of floodwaters into the system.
(b)
The applicant shall provide the Department of Planning and Community Development with assurance that new and replacement sanitary sewerage systems, including on-site systems, shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into the floodwaters.
(c)
The applicant shall provide the Department of Planning and Community Development with assurance that on-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
(d)
The storage of hazardous materials is prohibited.
(4)
Subdivision proposals.
(a)
All subdivision proposals shall be consistent with the need to minimize flood damage.
(b)
All subdivision proposals shall have public utilities and facilities, such as sewer, gas, electrical and water systems, located and constructed to minimize flood damage.
(c)
All subdivision proposals shall include adequate drainage paths to guide floodwaters around and away from the proposed structures and to reduce exposure to flood damage.
(d)
Base flood elevation data shall be provided for subdivision proposals and other proposed development which contains at least 50 lots or five acres, whichever is less.
(e)
Specific provisions on unsuitable development areas which include floodplains are referenced in and consistent with Dover Code Chapter 157, Land Subdivision Regulations (§§ 157-21, 157-22, and 157-60), and Chapter 170, Zoning (§§ 170-6, 170-29, and 170-32).
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
K.
Specific standards. In all areas of special flood hazard where base flood elevation data has been established per Subsection G(2), the following provisions are required:
(1)
Residential construction, new construction and substantial improvement of any residential structure shall have the lowest floor, including the basement, elevated to at least two feet above base flood elevation.
(2)
All new construction or substantial improvements of nonresidential structures shall have the lowest floor, including basement, elevated to at least two feet above the base flood elevation or, together with attendant utility and sanitary facilities, shall:
(a)
Be floodproofed so that below the base flood elevation the structure is watertight at least two feet above the base flood elevation with walls substantially impermeable to the passage of water;
(b)
Have structural components capable of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy; and
(c)
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)
Manufactured homes.
(a)
Manufactured homes shall be anchored in accordance with Subsection J(1)(b).
[Amended 10-13-2021 by Ord. No. 2021.09.08-006]
(b)
For new manufactured home parks and manufactured home subdivisions; for expansions to existing manufactured home parks and manufactured home subdivisions; for existing manufactured home parks and manufactured home subdivisions where the repair, reconstruction or improvement of the streets, utilities and pads equals or exceeds 50% of the value of the streets, utilities and pads before the repair, reconstruction or improvement has commenced; and for manufactured homes not placed in a manufactured park or manufactured home subdivision:
[1]
Stands or lots are elevated on compacted fill or on pilings so that the lowest floor of the manufactured home will be at least two feet above the base flood level.
[2]
Adequate surface drainage and access for a hauler are provided.
[3]
In the instance of elevation on pilings, lots are large enough to permit steps, piling foundations are placed in stable soil no more than 10 feet apart and reinforcement is provided for pilings more than six feet above the ground level.
(c)
Recreational vehicles placed on sites within areas of special flood hazard shall either:
[Amended 10-13-2021 by Ord. No. 2021.09.08-006]
(4)
For all new construction and substantial improvements, fully enclosed areas below the lowest floor that are subject to flooding are permitted, provided that the enclosed areas meet the following requirements:
(a)
The enclosed area is unfinished or flood-resistant, usable solely for parking of vehicles, building access or storage.
(b)
The area is not a basement.
(c)
The area 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 must either be certified by a professional engineer or architect or must 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.
[3]
Openings may be equipped with screens, louvers or other coverings or devices, provided that they permit the automatic entry and exit of floodwaters.
(5)
Proposed structures to be located on slopes within Zone AO shall include adequate drainage paths to guide floodwaters around and away from the proposed structures.
(6)
Accessory structures.
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
(b)
Any new construction and substantial improvement of any accessory structures without finished or habitable space shall not be used for the storage of hazardous materials.
(c)
It is recommended that any new construction and substantial improvement of any accessory structures without finished or habitable space meet the following standards:
[1]
The structure is not located in the floodway;
[2]
The structure is wet floodproofed and designed to allow for the automatic entry and exit of floodwater as detailed in Subsection K(4)(c);
[3]
When possible, the structure shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters and be placed further from the source of flooding than the primary structure; and
[4]
Service facilities such as electrical, mechanical and heating equipment shall be elevated or dry floodproofed to or above the base flood elevation.
(7)
All new residential structures or residential developments and all new nonresidential structures and nonresidential developments shall have all driveways and/or all road access or streets constructed with the driving surface at or above base flood elevation to ensure safe ingress and egress during a 100-year flood.
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
(8)
Critical facilities.
[Added 10-13-2021 by Ord. No. 2021.09.08-006]
(a)
All new critical facilities are prohibited within areas of special flood hazard.
(b)
Critical facilities that are to be replaced, substantially improved or meet the definition of "substantial damage" shall be constructed so that the lowest floor, including basement, shall be elevated or dry floodproofed at least two feet above the areas of special flood hazard. A critical facility shall have at least one access road connected to land outside the areas of special flood hazard and is capable of accommodating emergency services vehicles. The top of the access road shall be no lower than six inches below the base flood elevation of the area of special flood hazard.
L.
Regulatory floodways. Located within areas of special flood hazard established in Subsections C and I are areas designated as regulatory floodways. Since the regulatory floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles and erosion potential, the following provisions apply:
(1)
Along watercourses that have a designated regulatory floodway, no encroachments, including fill, new construction, substantial improvements or other development, are allowed within the designated regulatory 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. In Zone A, the Department of Planning and Community Development shall obtain, review and reasonably utilize any regulatory floodway data available from a federal, state or other source as criteria for requiring that development meet the regulatory floodway requirements of this subsection.
(2)
Along watercourses that have not had a regulatory floodway designated, no new construction, substantial improvements or other development (including fill), shall be permitted within Zone AE unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other 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.
M.
Variances and appeals.
(1)
Any order, requirement, decision or determination of any official of the Department of Planning and Community Development made under this section 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(b), the applicant shall have the burden of showing, in addition to the usual variance standards under New Hampshire statute, that:
(a)
The variance will not result in increased flood heights, additional threats to public safety, or extraordinary public expense.
(b)
If the requested variance is for activity within a designated regulatory floodway, no increase in flood levels during the base flood discharge will result.
(c)
The variance is the minimum necessary, considering the flood hazard, to afford relief.
(3)
The Zoning Board of Adjustment shall notify the applicant, in writing, that 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 such construction below the base level increases risks to life and property. Such notification shall be maintained with a record of all variance actions.