The following regulations in this section shall
apply to all lands designated as special flood hazard areas by the
Federal Emergency Management Agency (FEMA) in its Flood Insurance
Study of the County of Rockingham, NH, dated May 17, 2005, or as amended,
together with the associated Flood Insurance Rate Maps (FIRM), dated
May 17, 2005, or as amended, which are declared to be a part of this
chapter and are hereby incorporated by reference.
[Amended 6-5-2007; 2-16-2012; 9-13-2023]
For purposes of this article, certain words or terms shall be interpreted as defined herein. Where the definition of a word or term contained in this section conflicts with a similar word or term as defined in Article II of this chapter, the definition contained in this section shall apply only to these floodplain development provisions.
The floodplain within the Town of Derry subject to a one-percent
or greater possibility of flooding in any given year. The area designated
on the FIRM as Zones A and AE.
The flood having a one percent possibility of being equaled
or exceeded in any given year.
The elevation of surface water resulting from the “base
flood.”
Any area of a building having its floor subgrade (below ground
level) on all sides.
See "structure."
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, as defined by FEMA.
The Federal Emergency Management Agency.
An examination, evaluation and determination of flood hazards
and, if appropriate, corresponding water surface elevations, or an
examination and determination of mudslide or flood-related erosion
hazards.
An official map incorporated with this chapter on which FEMA
has delineated both the special flood hazard areas and the risk premium
zones applicable to the Town of Derry.
An opening in a foundation or enclosure wall that allows
automatic entry and exit of floodwaters. See FEMA “Technical
Bulletin 1, Openings in Foundation Walls and Walls of Enclosures.”
A general and temporary condition of partial or complete
inundation of normally dry land areas from:
Any land area 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.
See "regulatory floodway."
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
(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;
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;
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
Individually listed on a local inventory of historic places
in communities with historic preservation programs that have been
certified either:
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
enclosure is not built so as to render the structure in violation
of the applicable nonelevation design requirements of this chapter.
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 a site for greater than 180 days. This includes manufactured homes
listed in a manufactured home park or 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, or other
datum, to which base flood elevations shown on a community's Flood
Insurance Rate Map are referenced.
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.
Defined as:
Built on a single chassis;
Four hundred 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 cumulatively increasing the water surface elevation more than
a designated height.
See "area of special flood hazard."
Includes substantial improvements, and means the date the
building permit was issued, provided that 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 a site, such
as the pouring of slab or footings, the installation of piles, the
construction of columns, or any work beyond the state of excavation;
or the placement of a 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, footings,
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.
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.
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, addition, or other improvement
of a structure, the cost of which equals or exceeds 50% of the market
value of the structure before the “start of construction”
of the improvement. This term includes structures which have incurred
“substantial damage,” regardless of actual repair work
performed. The term does not, however, include either:
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 local code enforcement official
and which are the minimum 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.”
The failure of a structure or other development to be fully compliant with the community's floodplain management regulations. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required under § 165-55, 165-58B(2) or 165-57C and D of this chapter 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 (or other datum, where specified), of floods
of various magnitudes and frequencies in the floodplains.
All proposed development in any special flood
hazard areas 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. If a proposed building site is located in a special
flood hazard area, all new construction and substantial improvements
shall be:
A.
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.
Constructed with materials resistant to flood damage;
C.
Constructed by methods and practices that minimize
flood damage; and
D.
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.
Where new and replacement water and sewer systems
(including on-site systems) are proposed in a special flood hazard
area, 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 on-site waste disposal systems will be located to
avoid impairment to them or contamination from them during periods
of flooding.
[Amended 2-16-2012; 9-13-2023]
A.
For all new or substantially improved structures located in Zones
A and AE, the applicant shall furnish the following information to
the Building Inspector:
(1)
The as-built elevation (in relation to mean sea level) of the lowest
floor (including basement) and include whether or not such structures
contain 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.
(3)
Any certification of floodproofing.
B.
The Building Inspector shall maintain for public inspection and shall
furnish such information upon request.
The Building Inspector shall not grant 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.
[Amended 2-16-2012; 9-13-2023]
A.
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 Building Inspector,
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 Building Inspector, including notice
of all scheduled hearings before the Wetlands Bureau.
B.
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.
C.
Along watercourses that have a designated regulatory floodway, no
encroachments, including fill, new construction, substantial improvements,
or other development, are allowed within the floodway that would result
in any increase in flood levels within the community during the base
flood discharge.
D.
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 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.
E.
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."
|
[Amended 2-16-2012; 9-13-2023]
A.
In special flood hazard areas, 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 community's
Flood Insurance Study and accompanying FIRM.
(2)
In Zone A, the Building Inspector shall obtain, review and reasonably
utilize any one-hundred-year flood elevation data available from federal,
state, or other sources, including data submitted for development
proposals submitted to the community, e.g., subdivisions, site approvals,
etc. Where a base flood elevation is not available or not known for
Zone A, the base flood elevation shall be determined to be at least
two feet above the highest adjacent grade.
B.
The Building Inspector's base flood elevation determination will
be used as criteria for requiring, in Zones A and AE, that:
(1)
All new construction and substantial improvements of residential
structures have the lowest floor (including basement) elevated to
or above the base flood elevation;
(2)
All new construction and substantial improvements of nonresidential
structures have the lowest floor (including basement) elevated to
or above the base flood level, or, together with attendant utility
and sanitary facilities, shall:
(a)
Be floodproofed so that below the base flood elevation the structure
is watertight, 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)
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 be 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)
Recreation vehicles placed on sites within Zones A and AE shall either:
(a)
Be on the site for fewer than 180 consecutive days;
(b)
Be fully registered, on wheels or jacking system, attached to
the site only by quick disconnect type of utilities and security devices,
and have no permanently attached additions;
(c)
Meet all standards of this article and the elevation and anchoring
requirements for manufactured homes in this article.
(5)
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; and
(c)
The area shall be designed to automatically equalize hydrostatic
flood forces on exterior walls by allowing for the entry and exit
of floodwater. Designs for meeting this requirement must either be
certified by a registered professional engineer or architect or must
meet or exceed the following minimum criteria:
[1]
A minimum of two flood 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 floodwater.
[Amended 2-16-2012; 9-13-2023]
A.
Any order, requirement, decision or determination
of the Building Inspector made under these floodplain development
regulations may be appealed to the Zoning Board of Adjustment as set
forth in RSA 676:5.
B.
If the applicant, upon appeal, requests a variance
as authorized by RSA 674:33, I, in determining whether or not any
variance will be contrary to the spirit of these regulations, the
Board of Adjustment shall consider the following:
(1)
That the variance will not result in increased flood
heights, additional threats to public safety, or extraordinary public
expense;
(2)
That, if the requested variance is for activity within
a designated regulatory floodway, no increase in flood levels during
the base flood discharge will result; and
(3)
That the variance is the minimum necessary, considering
the flood hazard, to afford relief.
