Mathews County, VA Article III Establishment of Zoning Districts

§ 63-15 Description of special flood hazard districts.

Basis of districts:

A. The various special flood hazard districts shall include the SFHAs. The basis for the delineation of these districts shall be the FIS and the FIRM for Mathews County prepared by the Federal Emergency Management Agency, Federal Insurance Administration, dated 12-9-2014, and any subsequent revisions or amendments thereto.

B. Mathews County may identify and regulate local flood hazard or ponding areas that are not delineated on the FIRM. These areas may be delineated on a "Local Flood Hazard Map" using best available topographic data and locally derived information such as flood of record, historic high water marks or approximate study methodologies.

C. The boundaries of the SFHA Districts are established as shown on the FIRM which is declared to be a part of this chapter and which shall be kept on file at the Mathews County Building Department (office of the Building Official and Floodplain Administrator). According to the FIRM, Mathews County contains A, AE, Coastal A and VE Zones. Mathews County does not contain any delineated floodways or AO Zones.

(1) The AE Zone on the FIRM accompanying the FIS shall be those areas for which one-percent-annual-chance flood elevations have been provided and the floodway has not been delineated. The following provisions shall apply within an AE Zone:

(a) Until a regulatory floodway is designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within the areas of special flood hazard, designated as Zone AE 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 Mathews County. This requirement only applies along rivers, streams and other watercourses where FEMA has provided base flood elevations. The requirement does not apply along lakes, bays and estuaries, and the ocean coast.

(b) Development activities in Zone AE, on the Mathews County FIRM, which increase the water surface elevation of the base flood by more than one foot may be allowed, provided that the applicant first applies, with Mathews County endorsement, for a conditional letter of map revision, and receives the approval of the Federal Emergency Management Agency.

(2) The A Zone on the FIRM accompanying the FIS shall be those areas for which no detailed flood profiles or elevations are provided, but the one-percent-annual-chance floodplain boundary has been approximated. For these areas, the following provisions shall apply:

(a) The Approximated Floodplain District shall be that floodplain area for which no detailed flood profiles or elevations are provided, but where a one-hundred-year floodplain boundary has been approximated. Such areas are shown as Zone A on the maps accompanying the FIS. For these areas, the base flood elevations and floodway information from federal, state, and other acceptable sources shall be used, when available. Where the specific one-percent-annual-chance flood elevation cannot be determined for this area using other sources of data, such as the United States Army Corps of Engineers Floodplain Information Reports, United States Geological Survey Flood-Prone Quadrangles, etc., then the applicant for the proposed use, development and/or activity shall determine this base flood elevation. For development proposed in the approximate floodplain, the applicant must use technical methods that correctly reflect currently accepted nondetailed technical concepts, such as point on boundary, high-water marks, or detailed methodologies hydrologic and hydraulic analyses. Studies, analyses, computations, etc., shall be submitted in sufficient detail to allow a thorough review by the Floodplain Administrator.

(b) The Floodplain Administrator reserves the right to require a hydrologic and hydraulic analysis for any development. When such base flood elevation data is utilized, the lowest floor shall be elevated to or above the base flood level.

(c) During the permitting process, the Floodplain Administrator shall obtain:

[1] The elevation of the lowest floor (including the basement) of all new and substantially improved structures; and

[2] If the structure has been floodproofed in accordance with the requirements of this chapter, the elevation (in relation to mean sea level) to which the structure has been floodproofed.

(d) Base flood elevation data shall be obtained from other sources or developed using detailed methodologies comparable to those contained in a FIS for subdivision proposals and other proposed development proposals (including manufactured home parks and subdivisions) that exceed 50 lots or five acres, whichever is the lesser.

(3) The Coastal A Zone shall be those areas, as defined by the VA USBC, that are subject to wave heights between 1.5 feet and three feet, and identified on the FIRM as the area between the limits of moderate wave action (LiMWA) line and the VE Zone.

(a) Buildings and structures within this Zone shall have the lowest floor elevated to or above the base flood elevation plus one foot of freeboard, and must comply with the provisions in Article III, § 63-15C(1), and Article IV, §§ 63-17 and 63-18.

(4) The VE or V Zones on FIRMs accompanying the FIS shall be those areas that are known as "coastal high hazard areas," extending from offshore to the inland limit of a primary frontal dune along an open coast. For these areas, the following provisions shall apply:

(a) All new construction and substantial improvements in Zones V and VE (V if base flood elevation is available) shall be elevated on pilings or columns so that:

[1] The bottom of the lowest horizontal structural member of the lowest floor (excluding the pilings or columns) is elevated to or above the base flood elevation if the lowest horizontal structural member is parallel to the direction of wave approach or elevated at least one foot above the base flood elevation if the lowest horizontal structural member is perpendicular to the direction of wave approach; and

[2] The pile or column foundation and structure attached thereto is anchored to resist flotation, collapse, and lateral movement due to the effects of wind and water loads acting simultaneously on all building components. Wind and water loading values shall each have a one-percent chance of being equaled or exceeded in any given year (one-percent-annual-chance).

(b) A registered professional engineer or architect shall develop or review the structural design, specifications and plans for the construction, and shall certify that the design and methods of construction to be used are in accordance with accepted standards of practice for meeting the provisions of this chapter and the VA USBC.

(c) The Floodplain Administrator shall obtain the elevation (in relation to mean sea level) of the bottom of the lowest horizontal structural member of the lowest floor (excluding pilings and columns) of all new and substantially improved structures in Zones V and VE. The Floodplain Administrator shall maintain a record of all such information.

(d) All new construction and substantial improvement shall be located landward of the reach of mean high tide.

(e) All new construction and substantial improvements shall have the space below the lowest floor either free of obstruction or constructed with nonsupporting 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. For the purpose of this section, a breakaway wall shall have a design safe loading resistance of not less than 10 and no more than 20 pounds per square foot. Use of breakaway walls which exceed a design safe loading resistance of 20 pounds per square foot (either by design or when so required by local codes) may be permitted only if a registered professional engineer or architect certifies that the designs proposed meet the following conditions:

[1] Breakaway wall collapse shall result from water load less than that which would occur during the base flood; and

[2] 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 (structural and nonstructural). Maximum wind and water loading values to be used in this determination shall each have a one-percent chance of being equaled or exceeded in any given year.

(f) The enclosed space below the lowest floor shall be used solely for parking of vehicles, building access, or storage. Such space shall not be partitioned into multiple rooms, temperature-controlled, or used for human habitation.

(g) The use of fill for structural support of buildings is prohibited. When nonstructural fill is proposed in a coastal high hazard area, appropriate engineering analyses shall be conducted to evaluate the impacts of the fill prior to issuance of a development permit.

(h) The man-made alteration of sand dunes, which would increase potential flood damage, is prohibited.