(a) Design and Construction Standards. In order to prevent excessive damage to buildings, structures, and related utilities and facilities, the following restrictions apply to all development, subdivision proposals, manufactured home parks, new construction and to construction of substantial improvements, and the repair of substantial damage to existing structures occurring in the Floodplain Area.
(1) Basements and Lowest Floors.
A. All new construction, relocation and substantial improvements, including repair of substantial damage, of residential structures must have the lowest floor, including basement, ductwork and utilities, elevated to two feet above the Base Flood Elevation.
B. All new construction, relocation, substantial improvements, including repair of substantial damage, of nonresidential structures must have the lowest floor, including basement, ductwork and utilities, elevated to two feet above the Base Flood Elevation; or, together with attendant utility and sanitary facilities, be designed so that the structure is water tight with walls substantially impermeable to the passage of water from the lowest structural element to two feet above the Base Flood Elevation.
C. For all new construction, relocation, substantial improvements, and repair of substantial damage, those fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a Registered Professional Engineer or 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, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
(2) Manufactured Home Placement. All manufactured homes to be installed or substantially improved within the identified flood hazard areas of City of Dunbar shall be installed by a contractor possessing a valid West Virginia Manufactured Home Installer's license. Contractors shall install in accordance with the following standards:
A. The lowest floor, ductwork and utilities including HVAC/heat pump shall be elevated two feet above the Base Flood Elevation.
B. Elevation shall be on reinforced piers on a permanent foundation or other foundation elements of at least equivalent strength engineered for use in a flood hazard area. Installation designs incorporating dry stacked block piers shall not be used in flood hazard areas.
C. All manufactured homes shall be anchored to the permanent foundation in compliance with the requirements of 42 West Virginia Code of State Regulations, Series 19, Sections 10.1, 10.2, and 10b as authorized by West Virginia Code § 21-9-4. The anchoring shall be adequate to resist flotation, collapse, or lateral movement. Methods of anchoring may include but are not limited to the over- the-top and frame ties, attached to permanent foundation elements. Ground anchors are not adequate to satisfy flood specific anchoring requirements. This requirement is in addition to applicable State and local anchoring requirements for resisting wind forces.
D. Any additions to a manufactured home shall be similarly anchored.
E. A contractor possessing a valid WV Manufactured Home Installer's license shall certify in writing that the manufactured home has been installed to the standards set forth above.
(3) Appurtenant Structures.
A. Except as provided in subsection (a)(3)B. below, appurtenant structures shall be located out of the floodplain area or elevated to two feet above the Base Flood Elevation.
B. Where appurtenant structures not connected to the principal structure are to be located on sites below the Base Flood Elevation, the following flood damage reduction provisions apply:
1. Structures shall be no more than 600 square feet in size and valued at less than $10,000.00.
2. Floors shall be at or above grade on at least one side.
3. Structures shall be located, oriented and constructed to minimize flood damage.
4. Structures shall 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.
5. Flood resistant materials as detailed in FEMA Technical Bulletin 2-93 (FIA-TB-2) shall be used in the construction of the structure from the lowest structural element to two feet above the Base Flood Elevation.
6. Machinery, electric devices or appliances, and all utilities shall be located at least two feet above the Base Flood Elevation.
7. The venting requirements contained in Section 1749.06
(a)(1) are applicable and shall be strictly adhered to.
C. A Nonconversion Agreement shall be signed by the applicant stating that the use of the appurtenant structure or detached or attached garage shall not be changed from the use permitted, acknowledging that the structure may be subject to greater flood risk and that higher flood insurance premiums may be possible, and that a change in use may require full compliance with this Ordinance. The applicant agrees to notify prospective buyers of the existence of this agreement. It shall be the responsibility of the applicant to transfer the agreement at closing to the new owner via notarized signature. A copy of all new agreements shall be provided to the Floodplain Administrator. Failure to transfer the agreement and provide a signed copy to the Floodplain Administrator shall subject the violator to the penalties set forth in Section 1749.08
(c).
(4) Recreational Vehicle Placement.
A. Recreational vehicles to be placed within any floodplain area shall either:
1. Be on site for fewer than 180 consecutive days and/or,
2. Be fully licensed and ready for highway use. A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick disconnect utilities and security devices, and has no permanently attached additions. Or,
3. Be installed in accordance with the Manufactured Home Placement requirements and all other flood reduction requirements contained in this Ordinance.
(5) Fill.
A. The City of Dunbar officially recognizes the beneficial functions the floodplain serves in storage and transportation of water during floods. The City of Dunbar also finds that placement of fill in floodplains can have undesirable and detrimental affects on velocity, erosion and sedimentation rates causing increased flooding.
B. No fill shall be permitted in the floodway.
C. Placement of fill in other floodplain areas is restricted to functional purposes such as elevating a structure. Placement of fill to dispose of spoil from excavation or to elevate yards, parking lots, or fields will not generally be considered a functional purpose. The Floodplain Administrator may require the developer to provide compensatory storage before permitting fill. All fill placed in the floodplain area shall meet or exceed the following standards:
1. Fill shall be used only to the extent to which it does not adversely affect adjacent properties. The City of Dunbar may require the applicant to demonstrate through engineering reports that proposed fill would not adversely affect adjacent properties. When required, Hydrologic and hydraulic analyses shall be undertaken only by a registered professional engineer who shall certify that the technical methods used correctly reflect currently accepted technical concepts. The resultant study shall include a cover letter, signed and sealed by the responsible professional, providing a statement of findings in basic terms. In addition, studies, analyses, computations, etc., shall be submitted in sufficient detail to allow a thorough technical review by the City of Dunbar. During permit review the community shall consider the following issues that have the potential to cause adverse impact to adjacent properties:
a. Unacceptable increases in flood heights.
b. Blocking drainage from adjacent property.
c. Deflection of floodwaters onto adjacent existing structures.
d. Increases to stream velocity initiating or exacerbating erosion problems.
e. Other unique site conditions may be considered when determining whether fill will cause adverse impact to adjacent property including, but not limited to, subsidence areas, karst topography, stream blockages, and steep topography adjacent to the channel.
2. Fill shall be used only to the extent to which it does not adversely affect the capacity of channels or floodways of any tributary to the main stream, drainage ditch, or any other drainage facility or system.
3. Filled site must be contoured to drain properly (avoid ponding).
4. Fill shall extend beyond a structure for a sufficient distance to provide acceptable access. For residential structures, fill shall extend laterally fifteen (15) feet beyond the building line from all points before the start of sloping required in following subsection. For nonresidential structures, fill shall be placed to provide access acceptable for intended use. At grade access, with fill extending laterally fifteen (15) feet beyond the building line shall be provided to a minimum of twenty-five percent (25%) of the perimeter of a nonresidential structure.
5. Fill shall consist of soil or rock material only. Sanitary landfills shall not be permitted. No trash or woody debris shall be buried on site.
6. Fill material shall be compacted to provide the necessary stability and resistance to erosion, scouring or settling. Fill compaction standards must be appropriate to proposed post fill use. Particular attention is necessary when fill is being used to elevate a structure.
7. Fill slopes shall be no steeper than one (1) vertical on two (2) horizontal, unless substantiating data justifying steeper slopes are submitted to and approved by the Floodplain Administrator.
8. Fill site and fill must be protected from erosion.
a. Fill slopes exposed to flood waters with expected velocities during the occurrence of the base flood of five feet per second or less must be protected from erosion by covering them with grass, vines, weeds, or similar vegetative undergrowth.
b. Fill slopes exposed to flood waters with expected velocities during the occurrence of the base flood of greater than five feet per second must be protected from erosion by armoring them with stone or rock slope protection.
9. The applicant must submit any maps, computations or other material required by the Federal Emergency Management Agency (FEMA) to revise the Flood Insurance Study and/or Flood Insurance Rate Maps, when notified by the Floodplain Administrator, and must pay any fees or other costs assessed by FEMA for this purpose.
(6) Placement of Structures. All buildings and structures shall be constructed and placed on the lot so as to offer the minimum obstruction to the flow of water and shall be designed to have a minimum obstruction effect upon the flow and height of floodwaters.
A. Whenever possible, structures shall be constructed with the longitudinal axis parallel to the direction of flood flow and,
B. So far as practicable, structures shall be placed approximately on the same flood-flow lines as those of adjoining structures.
(7) Anchoring.
A. All buildings and structures including stream crossings shall be firmly anchored in accordance with accepted engineering practices to prevent flotation, collapse, and lateral movement, thus reducing the threat to life and property and decreasing the possibility of the blockage of bridge openings and other restricted sections of the watercourse.
B. All air ducts, large pipes, and storage tanks located at or below the Base Flood Elevation shall be firmly anchored to resist flotation.
(8) Flood Protection Setback.
A. A Flood Protection Setback equal to twice the width of the watercourse channel measuring from the top of one bank to the top of the opposite bank or 50 feet, whichever is less, shall be maintained from the top of the banks of all watercourses. To reduce erosion, natural vegetation shall be maintained in this area. Where natural vegetation does not exist along the watercourse and conditions for replanting are suitable, high priority shall be given to planting vegetation in the setback area to stabilize banks and enhance aquatic resources.
B. Necessary public works and temporary construction may be exempted from this subsection.
C. The Floodplain Administrator may consider an appeal to the Flood Protection Setback requirement if the applicant demonstrates that it is impossible to allow any development without encroachment into the Flood Protection Setback area. The appeal conditions shall be the minimum necessary and shall be made only after due consideration is given to varying other siting standards, such as side, front and back lot line setbacks.
(9) Storage.
A. No materials that are buoyant, flammable, explosive, or in times of flooding could be injurious to human, animal or plant life, shall be stored below Base Flood Elevation.
B. Storage of other material or equipment may be allowed if not subject to major damage by floods and firmly anchored to prevent flotation or readily removable from the area within the time available after flood warning.
C. Due to the potential of masking the natural elevation and making it more difficult to enforce this Ordinance, material that resembles "fill" material shall not be considered "storage" material for purposes of this subsection.
(10) Utility and Facility Requirements.
A. All new or replacement water systems whether public or private, shall be designed to minimize or eliminate infiltration of floodwaters into the systems.
B. All new or replacement sanitary disposal systems, whether public or private, shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters.
C. All other new or replacement public and/or private utilities and facilities shall be located and constructed to minimize or eliminate flood damage.
D. Onsite waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
(11) Drainage. Adequate drainage shall be provided to reduce exposure to flood hazard.
(12) Backflow Preventers. Back flow prevention valves should be used for all enciosed structures with sewage or drainage facilities located in the floodplain.
(Ord. 623. Passed 11-19-07.)