Rochester City Zoning Code
ARTICLE 13
Flood Hazard Overlay District FHOD
§ 275-13.1 Authority and purpose.
This article, adopted pursuant to the authority of RSA 674:16, shall be known as the "City of Rochester Floodplain Development Ordinance." The regulations in this article shall overlay and supplement the regulations in the City of Rochester Zoning Ordinance and shall be considered part of the Zoning Ordinance for purposes of administration and appeals under state law. If any provision of this article 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.
§ 275-13.2 Regulatory floodway boundaries.
The following regulations in this article shall apply to all lands designated as special flood hazard areas by the Federal Emergency Management Agency (FEMA) in its Flood Insurance Study, Strafford County, New Hampshire, together with the associated Flood Insurance Rate Maps dated May 17, 2005, which are declared to be a part of this article and are hereby incorporated by reference.
§ 275-13.3 Definitions.
As used in this article, the following words and phrases shall have the following meanings:
A designated AO or AH Zone on a community's Flood Insurance Rate Map (FIRM) with a one-percent or greater annual chance 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 a community subject to a one-percent or greater chance of flooding in any given year. The area may be designated as Zone A on the FHBM. After detailed ratemaking has been completed in preparation for publication of the FIRM, Zone A usually is refined into Zone A, AO, AH, A1-30, AE or A99.
The flood having a one-percent chance of being equaled or exceeded in any given year.
Any area of the building having its floor subgrade (below ground level) on all sides.
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.
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.
The Federal Emergency Management Agency.
An official map of the community on which the Federal Emergency Management Agency has delineated the regulatory floodway. This map should not be used to determine the current flood hazard zone or base flood elevation; the Flood Insurance Rate Map (FIRM) will be used to make determinations of flood hazard zones and base flood elevations.
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.
An official map of a community, issued by the Federal Emergency Management Agency, where the boundaries of the flood, mudslide (i.e., mudflow), and related erosion areas having special hazards have been designated as Zone A.
An official map of a community on which the Federal Emergency Management Agency has delineated both the special hazard areas and the risk premium zones applicable to the community.
See "Flood Elevation Study."
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.
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 sanitary 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-range storage or related manufacturing facilities.
The highest natural elevation of the ground surface prior to construction next to the proposed wall of a structure.
Any structure that is:
Listed individually on 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 non-elevation design requirements of this article.
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" also includes park trailers, travel trailers, and other similar vehicles placed on a site for greater than 180 consecutive days. For insurance purposes the term "manufactured home" does not include park trailers, travel trailers, and other similar vehicles.
A parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
For purposes of the National Flood Insurance Program, 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.
See "base flood."
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 one foot at any point. These areas are designated as floodways on the Flood Boundary and Floodway Map.
Relating to, formed by, or resembling a river (including tributaries), stream, brook, etc.
An area having special flood, mudslide (i.e., mudflow) and/or flood-related erosion hazards, and shown on an FHBM or FIRM as Zones A, AO, A1-30, A99, and AH. (See "area of special flood hazard.")
Includes substantial improvement 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 a 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, 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 not part of the main structure.
For floodplain 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 by 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 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 the appraised value prior to the start of the initial repair or improvement or, in the case of damage, the value of the structure prior to the damage occurring. 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 height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929 (or other datum, whether specified), of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas.
§ 275-13.4 Restrictions in regulatory floodway zone.
The following regulations, as well as the regulations contained in appropriate sections of this chapter, shall apply to the regulatory floodway zone as delineated in § 275-13.2 above:
A.
All proposed development in any special flood hazard areas shall require a permit.
B.
The Director of Building, Zoning, and Licensing Services 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 in a flood-prone area, all new construction and substantial improvements shall:
(1)
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;
(2)
Be constructed with materials resistant to flood damage;
(3)
Be constructed by methods and practices that minimize flood damage; and
(4)
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.
C.
The placement of a manufactured housing unit is prohibited within the designated regulatory floodway, except in existing manufactured housing parks.
D.
Within the regulatory floodway, any development or encroachment (including fill) which would result in any increase in flood levels during the base flood discharge is prohibited.
E.
Where new and replacement water and sewer systems (including on-site systems) are proposed in flood-prone areas, the applicant shall provide the Director of Building, Zoning, and Licensing Services with assurance that new and replacement sanitary sewage systems will be designed to minimize or eliminate infiltration of floodwaters, and on-site waste disposal systems will be located to avoid impairment to them or contamination from them during periods of flooding.
F.
The Director of Building, Zoning, and Licensing Services shall maintain for public inspection, and furnish upon request, any certification of floodproofing and the as-built elevation (in relation to mean sea level) of the lowest floor (including basement) of all new or substantially improved structures, and include whether or not such structures contain a basement. This information must be furnished by the applicant.
[Amended at time of adoption of Code (see Ch. 1, General Provisions, Art. II)]
G.
The Director of Building, Zoning, and Licensing Services shall review proposed developments 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. It shall be the responsibility of the applicant to certify these assurances to the Building Inspector.
H.
Watercourses.
(1)
In riverine situations, prior to the alteration or relocation of a watercourse, the applicant for such authorization shall notify the Wetlands Board of the New Hampshire Environmental Services Department and submit copies of such notification to the Director of Building, Zoning, and Licensing Services. Further, the applicant shall be required to submit copies of said notification to those adjacent communities as determined by the Director.
(2)
Within the altered or relocated portion of any watercourse, the applicant shall submit to the Director of Building, Zoning, and Licensing Services certification provided by a registered professional engineer assuring that the flood-carrying capacity of the watercourse has been maintained.
(3)
Along watercourses that have a designated regulatory floodway, no encroachments, including fill, new construction, substantial improvements, and other development, are allowed within the designated regulatory floodway that would result in any increase in flood levels within the community during the base flood discharge. In Zone A, the Director of Building, Zoning, and Licensing Services shall obtain, review, and reasonably utilize any floodway data available from a federal, state, or other source as criteria for requiring that development meet the floodway requirements of this article.
(4)
Along watercourses that have not had a regulatory floodway designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within Zones A1-30 on the FIRM, 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.
§ 275-13.5 Standards.
A.
In special flood hazard areas the Director of Building, Zoning, and Licensing Services shall determine the one-hundred-year flood elevation in the following order of precedence according to the data available:
(1)
In Zones A1-30 and AH, refer to the elevation provided in the community's Flood Insurance Study and accompanying FIRM or FHBM.
(2)
In unnumbered A Zones, the Director of Building, Zoning, and Licensing Services shall obtain, review, and reasonably utilize any one-hundred-year flood elevation data available from federal, state, development proposals submitted to the community (example: subdivisions, site approvals, etc.) or other source.
(3)
In Zone AO, the one-hundred-year 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.
The Director of Building, Zoning, and Licensing Services' one-hundred-year flood elevation determination will be used as criteria for requiring in Zones A1-30, AE, AH, AO and A that:
(1)
All new construction and substantial improvements of residential structures have the lowest floor (including basement) elevated to or above the one-hundred-year flood level.
(2)
All new construction and substantial improvements of nonresidential structures have the lowest floor (including basement) elevated to or above the one-hundred-year flood level 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 or practice for meeting the provisions of this article.
(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. Recreational vehicles placed on sites within Zones A, A1-30, AH and AE on the City's FIRM must either:
(4)
New construction and substantial improvements.
(a)
For all new construction and substantial improvements, fully enclosed areas below the lowest floor that are subject to flooding are permitted provided the enclosed areas meet the following requirements:
(b)
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 have 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 exist of floodwaters.
(5)
Proposed structures to be located on slopes in special flood hazard areas, Zones AH and AD, shall include adequate drainage paths to guide floodwaters around and away from the proposed structures.
§ 275-13.6 Variances and appeals.
A.
Any order, requirements, decision or determination of the Building Inspector made under this article 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(b), the applicant shall have the burden of showing, in addition to the usual variance standards under state law, 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, 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.
C.
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 twenty-five dollars ($25.) for one hundred dollars ($100.) of insurance coverage and such construction below the base flood level increases risks to life and property. Such notification shall be maintained with a record of all variance actions.
D.
The community shall maintain a record of all variance actions, including their justification for their issuance, and report such variances issued in its annual or biennial report submitted to FEMA's Federal Insurance Administrator.