In addition to the general requirements of Article III, the requirements of this section apply to all development proposed in special flood hazard areas.
A.
Elevation requirements.
(1)
The lowest floor (including basement) shall be elevated to or above
the base flood elevation plus 18 inches.
(2)
In areas of shallow flooding (Zone AO), the lowest floor (including
basement) shall be elevated at least as high above the highest adjacent
grade as the depth number specified in feet on the Flood Insurance
Rate Map plus 18 inches, or at least two feet plus 18 inches if a
depth number is not specified; adequate drainage paths shall be provided
to guide floodwaters around and away from the structure.
B.
Enclosures below the lowest floor.
(1)
Enclosures below the lowest floor shall be used solely for parking
of vehicles, building access, crawlspaces, or limited storage.
(2)
Enclosures below the lowest floor shall be constructed using flood-damage-resistant
materials. See FEMA Technical Bulletin #2, Flood Damage-Resistant
Materials Requirements.
(3)
Enclosures below the lowest floor (including crawlspaces) shall be
provided with flood openings which shall meet the following criteria
(see FEMA Technical Bulletin #1, Openings in Foundation Walls and
Walls of Enclosures):
(a)
There shall be a minimum of two openings on different sides
of each enclosed area; if a building has more than one enclosed area
below the design flood elevation, each area shall have openings on
exterior walls.
(b)
The total net area of all openings shall be at least one square
inch for each square foot of enclosed area, or the openings shall
be designed and certified by a registered engineer or architect to
provide for equalization of hydrostatic flood forces on exterior walls
by allowing for the automatic entry and exit of floodwaters.
(c)
The bottom of each opening shall be one foot or less above the
adjacent ground level.
(d)
Any louvers, screens or other opening covers shall allow the
automatic flow of floodwaters into and out of the enclosed area.
(e)
Where installed in doors and windows, openings that meet requirements of § 212-27B(3)(a) through (d) are acceptable; however, doors and windows without installed openings do not meet the requirements of this section.
(4)
Crawlspaces shall have the finished interior ground level equal to
or higher than the outside finished ground level on at least one entire
side of the foundation wall.
C.
Manufactured homes.
(1)
New or replacement manufactured homes, including substantial improvement
of existing manufactured homes, shall:
(a)
Be elevated on a permanent, reinforced foundation that raises the lowest floor to or above the base flood elevation plus 18 inches and is otherwise in accordance with § 212-27A.
(b)
Be installed in accordance with the anchor and tie-down requirements
of the building code or the manufacturer's written installation
instructions and specifications.
(2)
For the purpose of this requirement, the lowest floor of a manufactured
home is the bottom of the lowest horizontal supporting member of the
lowest floor.
A.
Elevation requirements.
(1)
The lowest floor (including basement) shall be elevated to or above the base flood elevation plus 18 inches or the structure shall be dry floodproofed in accordance with § 212-28B.
(2)
In areas of shallow flooding (Zone AO), if not dry floodproofed,
the lowest floor (including basement) shall be elevated at least as
high above the highest adjacent grade as the depth number specified
in feet on the Flood Insurance Rate Map plus 18 inches, or at least
two feet plus 18 inches if a depth number is not specified; adequate
drainage paths shall be provided to guide floodwaters around and away
from the structure.
B.
Dry floodproofing requirements. Dry floodproofed structures, together
with attendant utility and sanitary facilities, shall:
(1)
Be designed to be dry floodproofed such that the structure is watertight
with walls and floors substantially impermeable to the passage of
water to the level of the base flood elevation plus 18 inches. In
areas of shallow flooding (Zone AO), the structure shall be dry floodproofed
at least as high above the highest adjacent grade as the depth number
specified in feet on the Flood Insurance Rate Map plus 18 inches,
or at least two feet plus 18 inches if a depth number is not specified.
(2)
Have structural components capable of resisting hydrostatic and hydrodynamic
loads and effects of buoyancy.
(3)
Be certified by a licensed professional engineer or licensed professional
architect with a floodproofing certificate that the design and methods
of construction meet the requirements of this section. Refer to FEMA
Technical Bulletin #3, Non-Residential Floodproofing - Requirements
and Certification, for guidance.
Accessory structures shall meet the requirements of this chapter.
Accessory structures that have a footprint of no more than 200 square
feet may be allowed without requiring elevation or floodproofing provided
such structures meet all of the following requirements:
A.
Useable only for parking or limited storage;
B.
Constructed with flood-damage-resistant materials below the base
flood elevation;
C.
Constructed and placed to offer the minimum resistance to the flow
of floodwaters;
D.
Firmly anchored to prevent flotation, collapse, and lateral movement;
E.
Electrical service and mechanical equipment elevated to or above
the level of the base flood elevation plus 18 inches; and
G.
For guidance, see FEMA Technical Bulletin #7, Wet Floodproofing Requirements.
A.
Development in floodways.
(1)
Within any floodway area designated on the Flood Insurance Rate Map,
no encroachments, including fill, new construction, substantial improvements,
or other development shall be permitted unless it has been demonstrated
through hydrologic and hydraulic engineering analysis that the proposed
encroachment would not result in any increase in flood levels within
the community during the occurrence of the base flood discharge. Such
technical data shall be submitted to the Floodplain Administrator
and to FEMA. The analyses shall be prepared by a licensed professional
engineer in a format required by FEMA for a Conditional Letter of
Map Revision or Letter of Map Revision. Submittal requirements and
processing fees shall be the responsibility of the applicant.
(2)
The proposed development activity may be permitted if the analyses
demonstrate that the activity:
(a)
Will not result in any increase in the base flood elevation;
or
(b)
Will result in an increase in the base flood elevation, provided
a Conditional Letter of Map Revision has been issued by FEMA and the
applicant completes all of the following:
[1]
Submits technical data required in § 212-13A(8)(d);
[2]
Evaluates alternatives which would not result in increased base
flood elevations and an explanation why these alternatives are not
feasible;
[3]
Certifies that no structures are located in areas which would
be impacted by the increased base flood elevation;
[4]
Documents that individual legal notices have been delivered
to all impacted property owners to explain the impact of the proposed
action on their properties;
[5]
Requests and receives concurrence of the Mayor of the City of
Harrington and the Chief Executive Officer of any other community
impacted by the proposed actions; and
[6]
Notifies the Delaware Department of Natural Resources and Environmental
Control (Division of Watershed Stewardship).
B.
Development in areas with base flood elevations but no floodways.
(1)
For development activities in a special flood hazard area with base
flood elevations but no designated floodways, the applicant shall
develop hydrologic and hydraulic engineering analyses and technical
data reflecting the proposed activity and shall submit such analyses
and data to the Floodplain Administrator and to FEMA. The analyses
shall be prepared by a licensed professional engineer in a format
required by FEMA for a Conditional Letter of Map Revision or Letter
of Map Revision. Submittal requirements and processing fees shall
be the responsibility of the applicant.
(2)
The proposed development activity may be permitted if the analyses
demonstrate that the cumulative effect of the proposed development
activity, when combined with all other existing and potential special
flood hazard area encroachments will not increase the base flood elevation
more than one foot at any point.
C.
Deliberate alterations of a watercourse.
(1)
For the purpose of this chapter, a watercourse is deliberately altered
when a person causes a change to occur within its banks. Deliberate
changes to a watercourse include, but are not limited to, widening,
deepening or relocating of the channel; installation of culverts;
construction of bridges, and excavation or filling of the channel
or watercourse banks.
(2)
For any proposed deliberate alteration of a watercourse, the applicant
shall develop hydrologic and hydraulic engineering analyses and technical
data reflecting such changes and submit such technical data to the
Floodplain Administrator and to FEMA. The analyses shall be prepared
by a licensed professional engineer in a format required by FEMA for
a Conditional Letter of Map Revision or Letter of Map Revision. Submittal
requirements and processing fees shall be the responsibility of the
applicant.
(3)
The proposed alteration of a watercourse may be permitted upon submission,
by the applicant, of the following:
(b)
A description of the extent to which the watercourse will be
altered or relocated as a result of the proposed development.
(c)
A certification by a licensed professional engineer that the
bankful flood-carrying capacity of the watercourse will not be diminished.
(d)
Evidence that adjacent communities, the U.S. Army Corps of Engineers,
and the Delaware Department of Natural Resources and Environmental
Control (Division of Watershed Stewardship) have been notified of
the proposal and evidence that such notifications have been submitted
to the Federal Emergency Management Agency.
(e)
Evidence that the applicant shall be responsible for providing
the necessary maintenance for the altered or relocated portion of
the watercourse so that the flood-carrying capacity will not be diminished.
The Floodplain Administrator may require the permit holder to enter
into an agreement with the City of Harrington specifying the maintenance
responsibilities; if an agreement is required, the permit shall be
conditioned to require that the agreement be recorded on the deed
of the property which shall be binding on future owners.
