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HomeMy WebLinkAbout1988_4_20_Local_Law_No_3 I LOCAL LAW NO. 3 - 1988 FLOOD DAMAGE PREVENTION AN ACT to amend Chapter 28 of the Mamaroneck Town Code to replace existing Chapter 28, (enacted as L.L. No. 1 of '1979) with the following. BE IT ENACTED by the Town Board of the Town of Mamaroneck as follows: SECTION 1.0 STATUTORY AUTHORIZATION AND PURPOSE §1.1 FINDINGS The Town Board of the Town of Mamaroneck finds that the potential and/or actual damages from flooding and erosion may be a problem to the residents of the Town of Mamaroneck and that such damages may include: destruction or loss of private and public housing, damage to public facilities, both publicly and privately owned, and injury to and loss of human life. In order to minimize the threat of such damages and to achieve the purposes and objectives hereinafter set forth, this local law is adopted. §1.2 STATEMENT OF PURPOSE It is the purpose of this Local Law to promote the public health, safety, and general welfare, and to minimize public and private losses due to flood conditions in specific areas by provisions designed to: (1) regulate, restrict, or prohibit uses which are dangerous to health, safety and property due to water or erosion hazards, or which result in damaging increases in erosion or in flood heights or velocities; (2) require that uses and facilities which serve such uses, which are vulnerable to floods, be protected against flood damage at the time of initial construction; (3) minimize the alteration of natural floodplains, stream channels, and natural protective barriers which are involved in the accommodation of flood waters; (4) minimize or eliminate filling, grading, dredging and other development which may increase erosion or flood damages; (5) regulate the construction of flood barriers which will unnaturally divert flood waters or which may increase flood hazards to other lands, and; (b) qualify and maintain eligibility for participation in the National Flood Insurance Program. §1.3 OBJECTIVES The objectives of this Local Law are: (1) to protect human life and health; (2) to minimize expenditure of public money for costly flood control projects; (3) to minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public; (4) to minimize prolonged business interruptions; (5) to minimize damage to public and private facilities and utilities such as water and gas mains, electric, telephone, sewer lines, streets and bridges located in areas of special flood hazard; f (6) to help maintain a stable tax base by providing for the sound use and development of areas of special flood hazard so as to minimize future flood blight areas; (7) to provide that developers are notified that property is in an area of special flood hazard; and (B) to ensure that those who occupy the areas of special flood hazard assume responsibility for their actions. SECTION 2.0 DEFINITIONS Unless specifically defined below, words or phrases used in this Local Law shall be interpreted so as to give them the meaning they have in common usage and to give this Local Law its most reasonable application. "Appeal" means a request for a review of the Local Administrator's interpretation of any provision of this Local. Law or a request for a variance. "Area of shallow flooding" means a designated AO or VO Zone on a community's Flood Insurance Rate•Map (FIRM) with base flood depths from one to three feet where a clearly defined channel does not exist, where the path of flooding is unpredictable and indeterminate, and where velocity flow may be evident. "Area of special flood hazard" is the land in the floodplain within a community subject to a one percent or greater chance of flooding in any given year. This area may be designated as Zone A, AE, AH, AO, AI-99, V, Vo, VE, or V1-30. It is also commonly referred to as the base flood plain or 100-year floodplain. "Base flood" means the flood having a one percent chance of being equalled or exceeded in any given year. "Basement" means that portion of a building having its floor subgrade (below ground level.) on all sides. "Breakaway wall" means 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 the supporting foundation system. "Building" means any structure built for support, shelter, or enclosure for occupancy or storage. "Cellar" - has the same meaning as "Basement". "Coastal high hazard area" means the area subject to high velocity waters including, but not limited to, hurricane wave wash. The area is designated on a FIRM as Zone V1-30, VE, Vo or V. "Development" means any man-made change to improved or unimproved real estate, inculding but not limited to buildings or other structures, mining, dredging, filling, paving, excavation or drilling operations located within the area of special flood hazard. "Elevated building" means a non-basement building built to have the lowest floor elevated above the ground level by means of fill, solid foundation perimeter walls, pilings, columns (posts and piers), or shear walls. "Flood" or "Flooding" means a general and temporary condition of partial or compete inundation of normally dry land areas from: (1) The overflow of inland or tidal waters; or -2- (2) The unusual and rapid accumulation or runoff or surface waters from any source. "Flood Hazard Boundary Map (FREM)" means an official map of a community, issued by the Federal Emergency Management Agency, where the boundaries of the areas of special flood hazard have been defined but no water surface elevation is provided. "Flood Insurance Rate Map (FIRM)" means an official map of a community, on which the Federal Emergency Management Agency has delineated both the areas of special flood hazard and the risk premium zones applicable to the community. "Flood Insurance Study" is the official report provided by the Federal Emergency Management Agency. The report contains flood profiles, as elevations of the base flood. "Flood proofing" means any combination of structural and non-structuual 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. "Floodway" - has the same meaning as "Regulatory- Floodway". "Floor" means the tap surface of an enclosed area in a building (inclucing basement), i.e., top of slab in concrete slab construction or top of wood flooring in wood frame construction. "Functionally dependent use" means a use which cannot perform its intended purpose unless it is located or carried out in close proximity to water, such as a docking or port facility necessary for the loading and unloading of cargo or passengers, shipbuilding, and ship repair. The term does not include long-term storage, manufacture, sales, or service facilities. "Highest adjacent grade" means the highest natural elevation of the ground surface, prior to construction, next to the proposed walls of a structure. "Lowest Floor" means lowest level including basement or cellar of the lowest enclosed area. An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access, or storage in an area other than a basement 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 Local Law. "Manufactured home" means a structure, transportable in one or more sections, which is built on a permanent chassis and designed to be used with or without a permanent foundation when connected to the required utilites. The term also includes park trailers, travel trailers, and similar transportable structures placed on a site for 184 consecutive days or longer and intended to be improved property. "Mean Sea Level" means, 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. "Mobile home" - has the same meaning as "Manufactured home". "National Geodetic Vertical Datum (NGVD)", as corrected in 1929 is a vertical control used as a reference for establishing varying elevations within the flood plain. "New construction" means structures for which the "start of construction" commenced on or after the effective date of this Local Law. f i "Principally Above Ground" means that at least 51 percent of the actual cash value, excluding land value, is above ground. "100-year Flood" - has the same meaning as "ease Flood". "Regulatory Floodway" means 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 as determind by the Federal Emergency Management Agency in a Flood Insurance Study. "Sand dunes" means naturally occurring accumulations of-sand in ridges or mounds landward of the beach. "Start of Construction" means the initiation, excluding planning and design, of any phase of a project, physical alteration of the property, and shall include land preparation, such as clearing, grading, and filling; installation of streets and/or walkways; excavation for a basement, footings, piers, or foundations or the erection of temporary forms. It also includes the placement and/or installation on the property of accessory buildings (garages,sheds), storage trailers, and building materials. For manufactured homes the "actual start" means affixing of the manufactured home to its permanent site. "Structure" means a walled and roofed building, a manufactured home, or a gas or liquid storage tank, that is principally above ground. "Substantial improvement" means any repair, reconstruction, or improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure either: (1) before the improvement or repair is started; or (2) if the structure has been damaged and is being restored, before the damage occurred, For the purposes of this definition "substantial improvement" is considered to commence 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. The term does not, however, include either: (1) any project for improvement of a structure to comply with existing state or local building, fire, health, sanitary, or safety code specifications which are solely necessary to assure safe living conditions; or (2) any alteration of a structure or contributing structure listed on the National Register of Historic Places or a State Inventory of Historic Places. "Variance" means a grant of relief from the requirements of this local law which permits construction or use in a manner that would otherwise be prohibited by this Local Law. { -4- SECTION 3.0 GENERAL PROVISIONS .- §3.1 LANDS, TO WHICH THIS LOCAL LAW APPLIES This Local. Law shall apply to all areas of special flood hazards within the jurisdiction of the Town of Mamaroneck. 0.2 BASIS FOR ESTABLISHING THE AREAS OF SPECIAL FLOOD HAZARD The areas of special flood hazard identified by the Federal Emergency Management Agency in a scientific and engineering report entitled "The Flood Insurance Study for the Town of Mamaroneck, of Westchester County, New York", dated December 15, 1976, with accompanying Flood Insurance Rate Maps and Flood Boundary-Floodway Maps as said maps may, from time to time, be amended, is hereby adopted and declared to be a part of this Local Law. The Flood Insurance Study and map is on file at Town Center, 740 West Boston Post Road, ,Mamaroneck, New York. §3:3 INTERPRETATION, CONFLICT WITH OTHER LAWS This Local Law is adopted in response to revisions to the National Flood Insurance Program effective October 1, 1986 and shall supercede all Previous laws adopted for the purpose of establishing and maintaining eligibility for flood insurance. In their interpretation and application, the provisions of this Local Law shall be held to be minimum requirements adopted for the promotion of the public health, safety, and welfare. Whenever the requirements of this local law are at variance with the requirements of any other lawfully adopted rules, regulations, or ordinances, the most restrictive, or that imposing the higher standards, shall govern, §3.4 SEVERABILITY The invalidity of any section or provision of this Local Law shall not invalidate any other section or provision hereof. §3.5 PENALTIES FOR NON-COMPLIANCE No structure shall hereafter be constructed, located, extended, converted, or altered and no land shall be excavated or filled without full compliance with the terms of this Local Law and any other applicable regulations. Any infraction of the provisions of this Local Law by failure to comply with any of its requirements, including infractions of conditions and safeguards established in connection with conditions of the permit, shall constitute a violation. Any person who violates this Local Law or fails to comply with any of its requirements shall, upon conviction thereof, be fined no more than $250 or imprisioned for not more than 15 days, or both. Violators shall pay all costs and expenses involved in the case. Each day of noncompliance shall be considered a separate offense. Town Nothing herein contained shall prevent the Tow of Mamaroneck from taking such other lawful action as necessary to prevent or remedy an infraction, including injunctive relief. Any structure found not compliant with the requirements of this Local Law for which the developer and/or owner has not applied for and received an approved variance under Section 6,0 will be declared noncompliant ana notification sent to the Federal Emergency Management Agency. 51.6 WARNING AND DISCLAIMER OF LIABILITY The degree of flood protection required by •this Local Law is considered reasonable for regulatory purposes and is based on scientific and I -5- E engineering considerations. Larger-floods can and will occur on rare occasions. Flood heights may be increased by man-made or natural causes. This Local.Law does not imply that land outside the area of special flood hazards or-uses permitted within such areas will be free from flooding or flood damages. This Local Law shall not create liability on the part of the Town of Mamaroneck, any officer or employee thereof, or the Federal Emergency Management Agency, for any flood damages that result from reliance on this Local Law or any administrative decision lawfully made thereunder. SECTION 4.0 ADMINISTRATION §4.1 DESIGNATION OF THE LOCAL ADMINISTRATOR The Building Inspector is hereby appointed Local Administrator to administer and implement this Local Law by granting or denying development permit applications in accordance with its provisions. §4.2 ESTABLISHMENT OF DEVELOPMENT PERMIT A Development Permit shall be obtained before the start of construction or any other development within the area of special flood hazard as established in Section 3.2. Application for a Development Permit shall be made on forms furnished by the Local Administrator and may include, but not be limited to: plans, in duplicate drawn to scale and showing the nature, location, dimensions, and elevations of the area in question, existing or proposed structures, fill, storage of materials, drainage facilities, and the location of the foregoing. §4.2-1 APPLICATION STAGE The following information is required where applicable: (a) elevation in relation to mean sea level of the proposed lowest floor (including basement or cellar) of all structures; (b) elevation in relation to mean sea level to which any non-residential structure will be flood-proofed; (c) when required, a certificate from a licensed professional, engineer or architect that the utility flood-proofing will meet the criteria in Section 5.1-3(1); (d) certificate from a licensed professional engineer or architect that the non-residential flood-proofed structure will meet the flood-proofing criteria in Section 5.2-2; and (e) description of the extent to which any watercourse will be altered or relocated as'a result of proposed development. § 4.2-2 CONSTRUCTION STAGE Upon placement of the lowest floor, or flood-proofing by whatever means, or upon placement of the horizontal structural members of the lowest floor, whichever is applicable, it shall be the duty of the permit holder to submit to the local Administrator a certificate of the elevation of the lowest floor, flood-proofed elevation, or the elevation of the lowest portion of the l - z -6- horizontal structural members of the lowest floor, whichever, is applicable, as built, in relation to mean sea level. The elevation, certificate shall be prepared by or under the direct supervision of a licensed land surveyor or professional engineer f, and certified by same, When,flood-proofing is utilized for a particular building, the flood-proofing certificate shall be prepared by or under the direct supervision of a licensed professional engineer or architect and certified by same. Any further work undertaken prior to submission and approval of the certification shall be at the permit holder's risk. The Local Administrator shall review all data submitted. Deficiencies detected shall be cause to issue a Stop Work Order for the project unless immediately corrected. §4-3. DUTIES AND RESPONSIBILITIES OF THE LOCAL ADMINISTRATOR I Duties of the Local Administrator shall include, but not be limited to- §4.3-1 PERMIT APPLICATION REVIEW (1) Review all development permit applications to determine that the requirements of this Local Law have been satisified, (2) Review all development permit applications to determine that all necessary permits have been obtained from those Federal, State or local governmental agencies from which prior approval is required. (3) Review all development permit applications to determine if the proposed development adversely affects the flood carrying capacity of the area of special flood hazard. For the purposes of this Local Law, "adversely affects" means damage to adjacent properties because of rises in flood stages attributed to physical changes of the channel and adjacent overbank areas. An engineering study may be required of the applicant for this purpose. (i) If there is no adverse effect, then the permit shall be granted consistent with the provisions of this Local Law. (ii) If there is an adverse effect, then flood damage mitigation measures shall be made a condition of the permit. (4) Review all development permits for compliance with the provisions of Section 5.1-5, Encroachments, and of any other applicable local laws. § 4.3.2 USE OF OTHER BASE FLOOD DATA In addition to the base flood elevation data provided in accordance with Section 3.2, BASIS FOR ESTABLISHING AREAS OF SPECIAL FLOOD HAZARD, the Local Administrator shall obtain, review and reasonably utilize any base flood elevation data available from a Federal, State or other source, including data developed pursuant to Section 5,1-4(4) in order to administer Section 5.2, SPECIFIC STANDARDS. when such is available, the Local Administrator may obtain additional information in order to administer Section 5.2. § 4,3-3 INFORMATT9N TO BE OBTAINED AND MAINTAINED (1) obtain and record the actual elevation, in relation to mean sea level, of the lowest floor, including basement or cellar of all new or substantially improved structures, and whether or not the structure contains a basement or cellar. -7- r (2) For all new or substantially improved floodproofed structures: (i) obtain and record the actural elevation, in relation to mean sea level, to which the structure has been flood-proofed; and (ii) maintain the -flood-proofing certifications required in Sections 5.1 and 5.2. (3) In coastal high hazard areas, certification shall be obtained from a registered professional engineer or architect that the provisions of Section 5.3-2(3) are met. (4) Maintain for public inspection all records pertaining to the provisions of this Local Law, including variances, when granted, and Certificates of Compliance. § 4.3-4 ALTERATION OF WATERCOURSES (1) Notify adjacent communities, the Westchester County Department of Public Works, and the New York State Department of Environmental Conservation prior to any alteration, relocation, or narrowing of a watercourse, and submit evidence of such notification to the Regional Director, Federal Emergency Management Agency, Region II, 26 Federal Plaza, New York, NY 10278. (2) Require that maintenance is provided within the altered or relocated portion of said watercourse so that the flood carrying capacity is not diminished. §4.3-5 INTERPRETATION OF FIRM BOUNDARIES The Local Administrator shall have the authority to make interpretations when there appears to be a conflict between the limits of the federally identified area of special flood hazard and actual field conditions. Base flood elevation data established pursuant to Section 3.2 and/or Section 4.3-2, when available, shall be used to accurately delineate the area of special flood hazards. The Local Administrator shall use flood information from any other authoritive source, including historical data, to establish the limits of the area of special flood hazards when base flood elevations are not available. §4.3-6 STOP WORK ORDERS (1) All floodplain development found ongoing without an approved permit shall be subject to the issuance of a stop work order issued by the Local Administrator. Disregard of a stop work order shall be subject to the penalties and other remedies described in Section 3.5 of this Local Law. (2) All floodplain development found noncompliant with the provisions of this law and/or the conditions of the approved permit shall-be subject to the issuance of a Stop Work Order issued by the Local Administrator. Disregard of a stop Work Order shall be subject to the penalties and other remedies described in Section 3.5 of this Local Law. I -8- { §4.3-7 INSPECTIONS The Local Administrator and/or the developer's engineer or architect shall make periodic inspections at appropriate times throughout the period of construction in order to monitor compliance with permit conditions and enable said inspector to certify that the development is in compliance with the requirements of either the development permit or the approved variance. §4.3-8 CERTIFICATE OF COMPLIANCE (1) It shall be unlawful to use or occupy or to permit the use or occupancy of any building and/or premises, or part thereof hereafter created, erected, changed, converted or wholly or partly altered or enlarged in its use or structure until a Certificate of Compliance has been issued by the Local Administrator stating that the building or land conforms to the requirements of this local law. " (2) All other development occurring within the designated flood hazard area will have upon completion a Certificate of Compliance issued by the Local Administrator, All certifications shall be based upon the inspections conducted subject to Section 4.3-7 and/or any certified elevations, hydraulic information, floodproofing, anchoring requirements or encroachment analysis .which may have been required as a condition of the approved permit. SECTION 5.0 PROVISIONS FOR FLOOD HAZARD REDUCTION §5.1 GENERAL STANDARDS In all areas of special flood hazards the following standards are required; §5.1-1 ANCHORING (1) All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure. , (2) All manufactured homes shall be installed using methods and practices which minimize flood damage. Manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not to be 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. §5.1-2 CONSTRUCTION MATERIALS AND METHODS (1) All new construction and substantial improvements shall be constructed with materials and utility equipment resistant Lo flood damage. (2) All new construction and substantial improvements to existing construction shall be constructed using methods and practices that minimize flood damage. §5.1-3 UTILITIES (1) Electrical, heating, ventilation, plumbing, air conditioning equipment, and other service facilities shall be designed and/or located so as to prevent water from entering or -9- accumulating with the components during conditions of flooding. When designed for location below the base flood elevation, a professional engineer's or architect's certification is required; I .. (2) All new and replacement water supply systems shall be designed to minimize or'eliminate infiltration of flood waters into the system; (3) New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharge from the systems into the floodwaters; (4) On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding. §5.1-4 SUBDIVISION PROPOSALS (1) All subdivision proposals shall be consistent with the need to minimize flood damage; (2) All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage; (3) All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage and proper controls on the rate of runoff to prevent flood damage elsewhere. (4) Base flood elevation data shall be provided for subdivision proposals and other proposed developments (including proposals for manufactured home parks and subdivisions) greater than either 50 lots or 5 acres. { §5.1-5 ENCROACHMENTS (1) All proposed development in riverine situations where no flood elevation data is available (unnumbered A Zones) shall be analyzed to determine the effects on the flood carrying capacity of the area of special flood hazards set forth in Section 4.3-1(3), Permit Review. This may require the submission of additional technical data to assist in the determination. 55.2 SPECIFIC STANDARDS in all areas of special flood hazards where base flood elevation data has been provided as set forth in Section 3.2 BASIS FOR ESTABLISHING THE AREAS OF SPECIAL FLOOD HAZARD AREAS and Section 4.3-2, USE OF OTHER BASE FLOOD DATA, the following standards are required: §5.2-1 RESIDENTIAL CONSTRUCTION New construction and substantial improvements of any resident structure shall: (1) have the lowest floor, including basement or cellar, elevated-to or above the base flood elevation; (2) have fully enclosed areas below the lowest floor that are subject to flooding 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 licensed professional engineer or architect or-meet or exceed the ( following minimum criteria: -1a- (i) 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; (ii) the bottom of all such opening shall be no higher than one foot above the lowest adjacent finished grade; (iii) openings may be equipped with louvers, valves, screens or other coverings or devices provided they permit the automatic entry and exit of floodwaters. §5.2-2 NONRESIDENTIAL CONSTRUCTION New construction and substantial improvements of any commercial, industrial or other non-residential structure, together with attendant utility and sanitary facilities, shall_either: have the lowest floor, including basement or cellar, elevated to or above the base flood elevations; or be flood-proofed so that the structure is watertight below the base flood level with walls substantially impermeable to the passage of water, All structural components located below the base flood level must be capable of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy. (1) If the structure is to be elevated, fully enclosed areas below the base flood elevation shall be designed to automatically (without human intervention) allow for the entry and exit of floodwaters for the purpose of equalizing hydrostatic flood forces on exterior walls. Designs for meeting this requirement must either be certified by a licensed professional engineer or a licensed architect or meet the following criteria: E (i) 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; (ii) the bottom of all such openings shall be no higher than one foot above the lowest adjacent finished grade; and (iii) openings may be equipped with louvers, valves, screens or other coverings.or devices provided they permit the automatic entry and exit of floodwaters. (2) If the structure is to be flood-proofed: (i) a licensed professional engineer or architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with accepted standards of practice to make the structure watertight with walls substantially impermeable to the passage of water, with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and (ii) a licensed professional engineer or licensed land surveyor shall certify the specific elevation (in relation to mean sea level.) to which the structure is floodproofed. The Local Administrator shall maintain on record a copy of all such certificates noted in this section. §5.2-3 CONSTRUCTION STANDARDS FOR AREAS OF SPECIAL FLOOD HAZARDS WITHOUT BASE FLOOD ELEVATIONS (1) New construction or substantial improvements of existing structures including manufactured housing-shall have the - -li- lowest floor (includi4 basement) elevated at least 2 feet above the highest adjacent grade next to the proposed foundation of the structure. (2) Fully enclosed areas below the lowest floor that are subject to flooding shall be designed to automatically (without human intervention) allow for the entry and exit of floodwaters for the purpose of equalizing hydrostatic flood forces on exterior walls. Designs for meeting this requirement must either be certified by a licensed professinal engineer or a licensed architect or meet the following criteria (i) 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; (£i) the bottom of all such openings shall be no higher than one foot above the lowest adjacent finished grade; (iii) openings may be equipped with louvers, valves, screens or other coverings or devices provided they permit the automatic entry and exit of floodwaters. §5.3 COASTAL HIGH HAZARD AREA Coastal high hazard areas (V Zones) are located within the areas of special flood hazard established in Section 3.2. These areas have special flood hazards associated with high velocity waters from tidal surges and hurricane wave wash; therefore, the following provisions shall apply: §5.3-1 LOCATION OF STRUCTURES t All buildings or structures shall be located landward of the reach of the mean high tide. §5.3-2 CONSTRUCTION STANDARDS (1) Elevation Standards All new construction or,substantial improvements shall be elevated on pilings, columns (or shear walls) such that the lowest horizontal structural member supporting the lowest elevated floor (excluding columns, piles, diagonal bracing attached to the piles or columns, grade beams, pile caps and other members designed to either withstand storm action or break away without imparting damaging loads to the structure) is elevated to or above the level of the base flood so as not to impede the flow of water. (2) Determination of Loading Forces Structural design shall consider the effects of wind and water loads acting simultaneously during the Base Flood on all building components. Equations, procedures. and other,,guidance for determining and utilizing design values for these loadings are available in the documents referenced in section 13. (i) Water Loads The structural design shall be adequate to resist water forces that would occur during the Base Flood. Horizontal water loads considered shall include inertial and drag forces of waves, current drag forces, and impact forces { -12- f from waterborne storm"debris, Dynamic uplift loads shall also be considered if bulkheads; wall, or other natural man-made flow obstructions could cause wave runup beyond the elevation of the base flood. (iii) Wind Loads (a) Buildings shall be designed and constructed to resist the forces due to wind pressure. Wind forces on the superstructure include windward forces on vertical walls, uplift on the roof, internal forces when openings allow wind to enter the house, and upward force on the underside of the house when it is exposed. In the design, the wind should be assumed to blow potentially from any lateral direction relative to the house. (b) Design wind pressures on a building and its components shall be derived from wind velocities associated with storms with a 100 year mean recurrence interval. The 100 year design wind velocity is to be taken as 95 mph. The design method to be used is set forth by the American National Standards Institute, Section A58.1-1982. (3) Foundation Standards (i) The pilings or column foundation and structure attached thereto shall be adequately anchored to resist flotation, collapse or lateral movement due to the effects of wind and high velocity water loads acting simultaneously on all { building components. Foundations must be designed to transfer safely to the underlying soil all loads due to wind, water, dead load, live load and other loads (including uplift due to wind and water). (ii) Spread footings and fill material shall not be used for structural support of a new building or substantial improvement of an existing structure. (k) Pile Foundation Design Standards (i) Pile Spacing The design ratio of pile spacing to pile diameter shall not be less than 8,1 for individual piles; however, this would not apply to pile clusters located below the design grade. The maximum center-to-center spacing of wood piles shall not be more than 12 feet on center under load bearing sills, beams, or girders. (ii) Pile Embedment Pilings shall have adequate soil penetration (bearing capacity) to resist the combined wave and wind loads (lateral and uplift) associated with the Base Flood acting simultaneously with typical structure (live and dead) loads, and shall include consideration of decreased resistance capacity caused by erosion of soil strata surrounding the piles. The minimum penetration for foundation piles is to an elevation of 5 feet below mean sea level (msl) datum if the BFL is +10 msl or less, or to a least 10 feet below msl of the BFE is greater than +10 msl. i -13- (iii) Column Action -. i Pile foundation analysis shall also include consideration of piles in column action from the bottom of the structure to the stable soil cicvtion of the site. Pilings may be horizontally or diagonally braced to withstand wind and water forces. (iv) Pile Standards (a) The minimum acceptable sizes for timber piles are a tip diameter of 8 inches for round timber piles and 8 by 8 inches for square timber piles. All wood piles must be treated (in accordance with requirements of AWPA-C3) to minimize decay and damage from fungus. (b) Reinforced concrete piles shall be cast of concrete having a 28-day ultimate compressive strength of not less than 5,000 pounds per square inch, and shall be reinforced with a minimum of four longitudinal steel bars having a combined area of not less than 1 percent nor more than 4 percent of the gross concrete area. Reinforcement for precast piles shall have a concrete cover of not less than 1 114 inches for No. 5 bars and smaller and not less than 1 1/2 inches for No. 6 through No. 11 bars. Reinforcement for piles cast in the field shall have a concrete cover of not less than 2 inches. (v) Pile Installation Piles shall. be drived by means of a pile driver or drop hammer, jetted, or augered into place, i (vi) Bracing (a) Additional support for piles in the form of bracing may include lateral or diagonal bracing between piles. (b) When necessary, piles shall be braced at the ground line in both directions by a wood timber grade beam or a reinforced concrete beam. These at-grade supports should be securely attached to the piles to provide support even if scoured from beneath. (c) Diagonal bracing between piles, consisting of 2-inch by 8-inch (minimum) members bolted to the piles, shall be limited in location to below the lowest supporting structural member and above the stable soil elevation, and aligned in the vertical plane along pile rows perpendicular to the shoreline. Galvanized steel rods (minimum diameter 1/2 inch) or cable type bracing is permitted in any plane. (d) Knee braces, which stiffen both the upper portion of a pile and the beam-to-pile connection, may be used along pile rows perpendicular and parallel to the shoreline. Knee braces shall be 2-by-8 lumber bolted to the sides of the pile/beam, or 4--by-4 or larger braces framed into the pile/beam., Bolting shall consist of two 518-inch galvinized steel bolts (each end) for 2-by-8 members, or one 518-inch lag bolt (each end) for square members, Knee braces shall not extend more than 3 feet below the elevation of the base flood.' -14- t (5) Column Foundation Design Masonry piers or poured-in-place concrete piers shall be internally reinforced to resist vertical and lateral loads, and be connected with a moment-resisting connection to a pile cap or pile shaft. (6) Anchoring Standards All buildings and structures must have all components adequately anchored and continuously connected from the foundation to the roof, to prevent flotation, collapse, or permanent lateral movement during the Base Flood concurrent with the 100 year design wind velocity. (7) • Connectors and Fasteners Galvanized metal connectors, wood connectors, or bolts of size and number adequate for the calculated loads must be used to connect adjoining components of a structure. Toe nailing as a principal method of connection is not permitted. All metal connectors and fasteners used in exposed locations shall be steel, hot-dipped galvanized after fabrication. Connectors in protected interior locations shall be fabricated from galvinized sheet. (8) Beam to Pile Connections The primary floor beams or girders shall span the supports in the direction parallel to the flow of potential floodwater and wave action and shall be fastened to the columns or pilings by bolting, with or without cover plates. Concrete members shall be connected by reinforcement, if cast in place, or (if precast) shall be securely connected by bolting or welding. if sills, beams, or girders are attached to wood piling at a notch, a minimum of two (518)-inch galvanized steel bolts or two hot-dipped galvanized straps 3116 inch by 4 inches by 18 inches each bolted with two 112 inch lag bolts per beam member shall be used. Notching of.pile tops shall be the minimum sufficient to provide ledge support for beam members without unduly weakening pile connections. Piling shall not be notched so that the cross section is reduced below 50 percent. (9) Use of Space Below the Lowest Elevated Floor (i) The space below the lowest floor of all new construction or any existing building that is being altered, repaired or improved after the effective date of this Local Law shall be either kept free of obstructions or constructed with non-supporting breakaway walls, open wood lattice-work, or insect screening intended to collapse under wind and water loads without causing collapse, displacement, or other structural damage to the elevated portion of the building or supporting foundation system. (ii) The enclosed space below the lowest floor shall be used only for parking of vehicles, building access or storage. Use of this space for human habitation is expressly prohibited. The construction of stairs, stairwells and elevator shafts only are subject to the design requirements for breakaway walls in Section 5.3-2(10). -15- f � (10) Breakaway Wall Design Standards (i) A breakaway wall shall have a design safe loading resistance of not less than 10 and not more than 20 pounds per square foot. (ii) Grade beams shall be installed in both directions for all piles considered to carry the breakaway wall load. (Knee braces are required for front row piles that support breakaway walls.) (iii) Use of breakaway walls exceeding a design safeloading resistance of 20 pounds per square foot are permitted only if a licensed professional engineer or architect certifies in writing to the Local Administrator that the designs proposed meet the following conditions: (a) breakaway wall collapse shall result from a water load less than that which would bccur during the base flood; and (b) the elevated portion of the building and supporting foundation system shall not be subject to collapse, displacement, or other structural damage due to the effects of wind and water loads acting simultaneously on all building components. Maximum wind and water loading values to be used in this determination shall each have one percent chance of being equalled or exceeded in any given year (100-year mean recurrence interval). 1 (11) Utilities All machinery and equipment servicing the building must be elevated to or above the level of the base flood, including_ heating, ventilating, and air conditioning equipment, hot water heaters, appliances, elevator lift machinery, and electrical junction and circuit breaker boxes. Sanitary sewer and storm drainage that have openings below the level of the base flood shall be provided with automatic back€low valves or other automatic backflow devices that are installed in each discharge line passing through a building exterior wall. (12) Certification Requirements For all new construction and substantial improvements to residential structures in the Coastal High Hazard Area, applications for development permits shall be accompanied by design plans and specifications, prepared in sufficient detail to enable independent review of the foundation support and connnection components to be used in meeting Section 5.3-2(1-11) of this Law. Said plans and specifications shall be developed or reviewed by a licensed professional engineer or architect, and shall be accompanied by a statement, bearing the signature of that architect or engineer, certifying that the design and methods of construction to be used are in accordance with accepted standards of practice and with all applicable provisions of this Law. -16- (13) Reference Documents Standard reference documents for use with this Law in determining design wind and water farces on structures are; Wind -- American National Standards Institute,Inc., Minimum Design Loads for Buildings and Other Structures, ANSI A58,1-1092 New York, 1982), Water -- Waterways Experiment Station, Shore Protection Manual (two volumes) Department of the Army, Corps of Engineers,Coastal Engineering Research Center (1984). Guidance on the application of information from above reference documents, together with other design data and procedures, is provided in: Federal Emergency Management Agency, Coastal Construction Manual. (Washington, D.C., 1986), , §5,3-3 DISTURBANCE OF SAND DUNES There shall be no alteration of sand dunes which would increase potential flood damage. Any disturbance of sand and/or earthen material shall be conducted in strict compliance with State or local coastal Erosion Hazard Area regulations. 65.3-4 SUBMISSION AND MAINTENANCE OF CONSTRUCTION RECORDS (1) The applicant for a Development Permit for all new construction or substantial improvements shall submit in writing to the Local Administrator the followings (i) a statement certifying whether or not the structure contains a basement; and (ii) the elevation (in relation to mean sea level) of the bottom of the lowest structural member of the lowest floor of the structure. The elevation shall be certified by a licensed professional engineer or land surveyor. (2) The Local Administrator shall maintain a record of all information required under paragraph (1) of this Section. §5.4 REGULATORY FLOODWAY Located within areas of special flood hazard established in Section 3.2 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles, and erosion potential, the following provisions apply: (1) Prohibit encroachments, including fill, new construction, substantial improvements, and other development unless a technical evaluation demonstrates that encroachments shall not result in any increase in flood levels during the occurrence of the base ,flood discharge. (2) If Section 5.4 (1) is satisfied, all new construction and sustantial improvements shall comply with all applicable flood hazard reduction provisions of Section 5.8 Provisions for Flood Hazard Reduction. -17- { SECTION 6.0 VARIANCE PROCEDURE 46.1 APPEALS BOARD (1) The Planning Board, as established by the Town Board of the Town of Mamaroneck, shall hear and decide appeals and requests for variances from the requirements of this Local. Law. (2) The Planning Board shall hear and decide appeals when it is alleged there is an error in any requirement, decision, or determination made by the Local Administrator in the enforcement or administration of this Local Law. (3) Those aggrieved by the decision of the Planning Board, may appeal such decision to the Supreme Court pursuant to Article 78 of the Civil Practice Law and Rules, within 30 days of the filing of said decision. (4) In passing on such application, the Planning Board, shall consider all technical evaluations, all relevant factors, standards specified in other sections of this Local Law ands (i) the danger that materials may be swept onto other lands to the injury of others; (ii) the danger to life and property due to flooding or erosion damage; (iii) the susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner; (iv) the importance of the services provided by the proposed facility to the community; (v) the necessity to the facility of a waterfront location, where applicable; (vi) the availability of alternative locations for the proposed use which are not subject to flooding or erosion damage; (vii) the compatibility of the proposed use with existing and anticipated development; (viii) the relationship of the proposed use to the comprehensive plan and flood plain management program of that area. (ix) the safety of access to the property in times of flood for ordinary and emergency vehicles; (x) the costs to local governments and the dangers associated with conducting search and rescue operations during periods of flooding; (xi) the expected heights, velocity, duration, rate of rise, and sediment transport of the flood waters and the effects of wave action, if applicable, expected at the site; and (xii) the costs of providing governmental services during and after flood conditions, including search and rescue . operations, maintenance and repair of public utilities and facilities such as sewer, gas, electrical, and water systems and streets and bridges. { (5) Upon consideration of the factors of Section 6.1(4) and the purposes of this Local Law, the Planning Board may attach such conditions to the granting of variances as it deems necessary to further the purposes of this Local Law. (.6) the Local Administrator shall maintain the records of all appeal actions including technical information and report any variances to the Federal Emergency Management Agency upon request. §6.2 CONDITIONS FOR VARIANCES (1) Generally, variances may be issued for new construction and substantial improvements to be erected on a lot of one-half acre or Jess in size.contiguous to and surrounded by lots with existing structures constructed below the base flood level, provided items (i-xii) in Section 6.1 (4) have been fully considered. As the lot size increases beyond the one-half acre, the technical justification required for issuing the variance Increases. (2) Variances may be issued for the reconstruction, 'rehabilitation or restoration of structures and contributing structures listed on the National Register of Historic Places or the State Inventory- of Historic Places, without regard to the contributing structures procedures set forth in the remainder of this section. (3) Variances may be issued by a community for new construction and substantial improvements and for other development necessary for the conduct of a functionally dependent use provided that: (i) the criteria of subparagraphs 1,4,5,and 6 of this section are met; (ii) the'structure or other development is protected by methods that minimize flood damages during the base flood and create no additional threat to public safety. (4) Variances shall not be issued within any designated floodway if any--:increase in flood levels during the base flood discharge would result. (5) Variances shall only be issued upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief. (6) Variances shall only be issued upon receiving written justification: (i) a showing of good and sufficient cause; (ii) a determination that failure to grant the variance would result in exceptional hardship to the applicant; and (iii) determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisances, cause fraud on or victimization of the public or conflict with existing local laws or ordinances. (7) Any applicant to whom a variance is granted for a building with the lowestAloor below the base flood elevation shall he given written notice that the cost of flood insuance will be commensurate with the increased risk resulting from lowest floor elevation. -19- i SECTION 7 Local Law No. 1 of 1979 is hereby repealed. SECTION 8 This local Law shall take effect immediately. -20-