This article, adopted pursuant to the authority
of RSA 674:16, shall be known as the "City of Nashua Floodplain Development
Ordinance."
The regulations in this chapter shall overlay and supplement the regulations in Part 2 of this chapter and shall be considered part of Part 2 for purposes of administration and appeals under state law. If any provision of this chapter 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.
[Amended 9-8-2009 by Ord. No. O-09-66; 3-8-2011 by Ord. No.
O-11-52]
The following regulations in this chapter 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 County of Hillsborough, N.H." dated September 25, 2009,
together with the associated Flood Insurance Rate Maps dated September
25, 2009, including the revised map panels 33011C0514E and 3011C0652E
dated April 18, 2011, which are declared to be a part of this chapter
and are hereby incorporated by reference, and any subsequent revisions
thereto.
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 City of Nashua.[1]
A designated AO Zone on the Flood Insurance Rate Map (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.
[Amended 9-8-2009 by Ord. No. O-09-66]
The land in the floodplain within the City of Nashua subject
to a one-percent-or-greater possibility of flooding in any given year.
The area is designated as Zone A, AO, and AE on the Flood Insurance
Rate Map.
[Amended 9-8-2009 by Ord. No. O-09-66]
The flood having a one-percent possibility of being equaled
or exceeded in any given year.
Any area of a building having its floor subgrade 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.
[Amended 9-8-2009 by Ord. No. O-09-66]
The Federal Emergency Management Agency.
A general and temporary condition of partial or complete
inundation of normally dry land areas from:
The official maps incorporated with this chapter, on which
FEMA has delineated both the special flood hazard areas and the risk
premium zones applicable to the City of Nashua.
An examination, evaluation and determination of flood hazards
and, if appropriate, corresponding water surface elevations, or an
examination, evaluation and determination of mudslide or flood-related
erosion hazards.
[Amended 9-8-2009 by Ord. No. O-09-66]
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."
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.
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
an 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 site for greater than 180 consecutive days. This includes manufactured
homes located in a manufactured home park or subdivision.
[Amended 9-8-2009 by Ord. No. O-09-66]
A parcel (or contiguous parcels) of land divided into two
or more manufactured home lots for rent or sale.
[Added 9-8-2009 by Ord. No. O-09-66]
The National Geodetic Vertical Datum (NGVD) of 1929 or other
datum, to which base flood elevations shown on a communities Flood
Insurance Rate Map are referenced.
For the purpose 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 improvement to such structures.
[Added 9-8-2009 by Ord. No. O-09-66]
See "base flood."
A vehicle that is:
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 increasing the water surface elevation. These areas are designated
as floodways on the Flood Insurance Rate Map.
[Amended 9-8-2009 by Ord. No. O-09-66; 5-11-2021 by Ord. No. O-21-058]
 |
See "area of special flood hazard."
[Amended 9-8-2009 by Ord. No. O-09-66]
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.
Includes substantial improvements, and means 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 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, 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.
Damage of any origin sustained by a structure whereby the
cost of restoring the structure to its prior condition would equal
or exceed 50% of the market value of the structure before the damage
occurred.
Any combination of repairs, reconstruction,
alteration, or improvements to a structure in which the cumulative
cost equals or exceeds 50% of the market value of the structure. The
market value of the structure should equal:
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, however, 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.
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 in
44 CFR § 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.
[Added 9-8-2009 by Ord. No. O-09-66]
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.
[Amended 5-11-2021 by Ord. No. O-21-058]
The Department of Building Safety 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 development shall:
A.
Be designed (or modified) and adequately anchored
to prevent floatation, collapse, or lateral movement of the structure
resulting from hydrodynamic and hydrostatic loads, including the effects
of buoyancy;
B.
Be constructed with materials resistant to flood damage;
C.
Be constructed by methods and practices that minimize
flood damages;
D.
All nonresidential development: 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; and
E.
All residential
development, including new construction, placements of new manufactured
homes, and substantial improvements, be constructed with electrical,
heating, ventilation, plumbing, and air conditioning equipment, and
other service facilities that are located at least one foot above
base flood elevation so as to prevent water from entering or accumulating
within the components during conditions of flooding.
[Amended 5-11-2021 by Ord. No. O-21-058]
Where new or replacement water and sewer systems
(including on-site systems) are proposed in a special flood hazard
area, the applicant shall provide the Administrative Officer 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 at least one foot above the base flood elevation to avoid
impairment to them or contamination from them during periods of flooding.
[Amended 9-8-2009 by Ord. No. O-09-66; 5-11-2021 by Ord. No. O-21-058]
A.
For all new or substantially improved structures located
in Zones A, AE or AO, the applicant shall furnish the following information
to the Department of Building Safety:
(1)
The Elevation Certificate stating as-built elevation
(in relation to NAVD88) 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 NAVD88) to which the structure was floodproofed.
(3)
Any certification of floodproofing.
B.
The Department of Building Safety shall maintain the
aforementioned information for public inspection, and shall furnish
such information upon request in accordance with NH RSA 91-A..
[Amended 9-8-2009 by Ord. No. O-09-66]
All proposed development in any special flood
hazard area shall require a permit. The Administrative Officer 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.
A.
Notice. 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 Environmental
Services Department and submit copies of such notification to the
Administrative Officer, in addition to the copies required by RSA
482-A:3. Further, the applicant shall submit copies of said notification
to those adjacent communities as determined by the Administrative
Officer, including notice of all scheduled hearings before the Wetlands
Bureau.
B.
Certification. The applicant shall submit to the Administrative
Officer, a 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.
Watercourses within regulatory floodways. 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 9-8-2009 by Ord. No. O-09-66]
D.
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 9-8-2009 by Ord. No. O-09-66]
E.
The Administrative
Officer 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 requirement:
[Added 9-8-2009 by Ord. No. O-09-66]
|
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.
|
A.
Determination of flood elevation. In special flood
hazard areas the Administrative Officer shall determine the one-hundred-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 community's Flood Insurance Study and accompanying FIRM.
[Amended 9-8-2009 by Ord. No. O-09-66]
(2)
In Zone A, the Administrative Officer shall obtain,
review, and reasonably utilize any one-hundred-year flood elevation
data available from any federal, state or other source, including
data submitted for development proposals submitted to the community
(i.e., subdivisions, site approvals). Where a 100-year flood elevation
is not available or not known, the flood elevation shall be determined
to be at least two feet above the highest adjacent grade.
[Amended 9-8-2009 by Ord. No. O-09-66; 5-11-2021 by Ord. No. O-21-058]
(3)
In Zone AO, the 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.
B.
Criteria. The Administrative Officer's one-hundred-year
flood elevation determination will be used as criteria for requiring
in Zones A, AE and AO that:
[Amended 9-8-2009 by Ord. No. O-09-66; 5-11-2021 by Ord. No. O-21-058]
(1)
All new construction or substantial improvement of
residential structures have the lowest floor (including basement)
elevated at least one foot above the 100-year flood elevation.
(2)
That all new construction or substantial improvements
of nonresidential structures have the lowest floor (including basement)
elevated at least one or two feet above the one-hundred-year flood
level depending on the Flood Design Class (one foot for Flood Design
Classes 1, 2 and 3 and two feet or the 500-year flood elevation, whichever
is higher for Flood Design Class 4) or to the design flood elevation,
whichever is higher or, together with attendant utility and sanitary
facilities, shall:
(a)
Be floodproofed so that below the one-hundred-year
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 least one foot above the base flood level; and be securely
anchored to resist floatation, 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.
(4)
All recreational 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 licensed and ready for highway use;
or
(c)
Meet all standards of Section 60.3(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.
(5)
For all new construction and substantial improvements,
fully enclosed areas below the lowest floor that are subject to flooding
are permitted, provided that they meet the following requirements:
(a)
The enclosed area is unfinished or flood-resistant,
usable solely for the parking of vehicles, building access or storage;
(b)
The area is not a basement;
(c)
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 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.
(6)
Proposed structures to be located on slopes in special
flood hazard areas, Zones AH and AO shall include adequate drainage
paths to guide floodwaters around and away from the proposed structures.
The requirements of this article apply to applications
for subdivision and site plan approval. Requirements for subdivisions/site
plans having land designated as special flood hazard areas (SFHA)
by the National Flood Insurance Program (NFIP) are as follows:
A.
The Planning Board shall review the proposed development
to assure 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.
B.
The Planning Board shall require that all proposals
for development greater than 50 lots or five acres, whichever is the
lesser, include base flood elevation (BFE) data within such proposals
(i.e., floodplain boundary and one-hundred-year flood elevation).
C.
The Planning Board shall require the applicant to
submit sufficient evidence (construction drawings, grading and land
treatment plans) so as to allow a determination that:
(1)
All such proposals are consistent with the need to
minimize flood damage;
(2)
All public utilities and facilities, such as sewer,
gas, electrical, and water systems are located and constructed to
minimize or eliminate flood damage; and
(3)
Adequate drainage is provided so as to reduce exposure
to flood hazards.
A.
Appeals. Any order, requirement, decision or determination of the Administrative Officer made under this chapter may be appealed to the Zoning Board of Adjustment as set forth in RSA 676:5 and Part 3 of this chapter.
B.
Variances. If the applicant, upon appeal, requests
a variance as authorized by RSA 674:33, the applicant shall have the
burden of showing in addition to the usual variance standards under
state law that:
[Amended 5-11-2021 by Ord. No. O-21-058]
(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, no increase in flood levels during
the base flood discharge will result.
(3)
The variance is the minimum necessary, considering
the flood hazard, to afford relief.
