Sec. 28-960

Floodplain

• Contour interval2 ft

  Property with slopes less than 20 percent shall show contours at intervals of two feet.

• Elevated building use restriction

  Fully enclosed areas, of proposed new construction or substantially improved structures, which are below the regulatory flood protection elevation shall not be designed or used for human habitation, but shall only be used for parking of vehicles, building access, or limited storage of maintenance equipment used in connection with the premises.

• Flood vent bottom heightMaximum heightThe tallest a building may be, given in feet, in storeys, or both — whichever binds first.1 ft

  The bottom of all required openings shall be no higher than one foot above the adjacent grade.

• Flood vent openings1 sq in per sq ftsq ftSquare feet. An acre is 43,560 sq ft; a typical suburban lot is 7,000–10,000.

  The total net area of all openings must be at least one square inch for each square foot of enclosed area subject to flooding.

• Floodway encroachment prohibition

  Within the floodway district, no encroachments, including fill, new construction, substantial improvements, or other development shall be permitted unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in the base flood elevation.

• Lowest floor elevation in Zone A

  Within the approximated floodplain district, all new construction and substantial improvements shall have the lowest floor elevated to or above the base flood elevation. The base flood elevation shall be determined by the zoning administrator using the best available data.

• Lowest floor elevation in Zone AE

  Within the special floodplain district, all new construction and substantial improvements shall have the lowest floor elevated to or above the base flood elevation.

• Lowest floor elevation in Zone X (shaded)1 ft

  Within the other flood districts, all new construction and substantial improvements shall have the lowest floor elevated to or above the base flood elevation plus one foot of freeboard.

• Manufactured homeManufactured homeA dwelling built in a factory to a federal standard and transported to the site. elevation1 ft

  Shall have the lowest floor elevated to one foot above the base flood elevation.

• Manufactured homeManufactured homeA dwelling built in a factory to a federal standard and transported to the site. prohibition

  The placement of any manufactured home (mobile home) within any flood hazard district is specifically prohibited, except as a replacement for a manufactured home on an individual lot or parcel or in an existing manufactured home park or subdivision.

• Nonresidential lowest floor elevation1 ft

  New construction or substantial improvement of any commercial, industrial, or nonresidential building shall have the lowest floor, including basement, elevated to at least one foot above the base flood elevation.

• Recreational vehicle 180-day rule180 days

  All recreational vehicles placed on sites must either be on the site for fewer than 180 consecutive days; be fully licensed and ready for highway use; or meet all the requirements for manufactured homes.

• Residential lowest floor elevation1 ft

  New construction or substantial improvement of any residential structure shall have the lowest floor, elevated to at least one foot above the base flood elevation.

• Special use permitConditional useAllowed only after a discretionary approval — usually a public hearing and a board vote. required

  All uses, activities and development occurring within any flood hazard district shall be undertaken only upon the issuance of a special use permit.

• Subdivision base flood elevation data

  It is required that all subdivision proposals greater than 25 lots or five acres, whichever is the lesser, shall include base flood elevation data.

• Watercourse alteration permit

  Prior to any proposed alteration or relocation of any channels or of any watercourse, stream, etc., within this jurisdiction a permit shall be obtained from the U.S. Corps of Engineers, the Virginia Department of Environmental Quality, and the Virginia Marine Resources Commission.