In all areas of special flood hazards the following standards
are required:
A. Anchoring.
All new construction and substantial improvements of structures, including
manufactured homes, shall be adequately anchored to prevent flotation,
collapse or lateral movement of the structure resulting from hydrodynamic
and hydrostatic loads, including the effects of buoyancy.
B. Construction
Materials and Methods. All new construction and substantial improvements
of structures, including manufactured homes, shall be constructed:
1. With
flood-resistant materials, and utility equipment resistant to flood
damage for areas below the base flood elevation;
2. Using
methods and practices that minimize flood damage;
3. With
electrical, heating, ventilation, plumbing and air conditioning equipment
and other service facilities that are designed and/or located so as
to prevent water from entering or accumulating within the components
during conditions of flooding; and
4. Within
Zones AH or AO, so that there are adequate drainage paths around structures
on slopes to guide floodwaters around and away from proposed structures.
C. Elevation
and Floodproofing.
1. Residential
Construction. All new construction or substantial improvements of
residential structures shall have the lowest floor, including basement:
a. In AE, AH, A1-30 Zones, elevated to or above the base flood elevation.
b. In an AO Zone, elevated above the highest adjacent grade to a height
equal to or exceeding the depth number specified in feet on the FIRM,
or elevated at least two feet above the highest adjacent grade if
no depth number is specified.
c. In an A Zone, without BFEs specified on the FIRM (unnumbered A zone), elevated to or above the base flood elevation; as determined under Section
15.68.130(C).
Upon the completion of the structure, the elevation of the lowest
floor, including basement, shall be certified by a registered civil
engineer or licensed land surveyor, and verified by the community
building inspector to be properly elevated. Such certification and
verification shall be provided to the Floodplain Administrator.
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2. Nonresidential Construction. All new construction or substantial improvements of nonresidential structures shall either be elevated to conform with subsection
(C)(1) of this section or:
a. Be floodproofed, together with attendant utility and sanitary facilities, below the elevation recommended under subsection
(C)(1) of this section, so that the structure is watertight with walls substantially impermeable to the passage of water;
b. Have structural components capable of resisting hydrostatic and hydrodynamic
loads and effects of buoyancy; and
c. Be certified by a registered civil engineer or architect that the standards of subsections
(C)(2)(a) and
(b) of this section are satisfied. Such certification shall be provided to the Floodplain Administrator.
3. Flood
Openings. All new construction and substantial improvements of structures
with fully en-closed areas below the lowest floor (excluding basements)
that are usable solely for parking of vehicles, building access or
storage, and which are subject to flooding, shall be designed to automatically
equalize hydrostatic flood forces on exterior walls by allowing for
the entry and exit of floodwater. Designs for meeting this requirement
must meet the following minimum criteria:
a. For non-engineered openings:
i. Have a minimum of two openings on different sides 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 openings shall be no higher than one foot above
grade;
iii.
Openings may be equipped with screens, louvers, valves or other
coverings or devices provided that they permit the automatic entry
and exit of floodwater; and
iv. Buildings with more than one enclosed area must have openings on
exterior walls for each area to allow floodwater to directly enter;
or
b. Be certified by a registered civil engineer or architect.
5. Garages
and Low Cost Accessory Structures.
a. Attached Garages.
i. A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry of floodwaters. See subsection
(C)(3) of this section. Areas of the garage below the BFE must be constructed with flood resistant materials. See subsection
B of this section.
ii. A garage attached to a nonresidential structure must meet the above
requirements or be dry flood-proofed. For guidance on below grade
parking areas, see FEMA Technical Bulletin TB-6.
b. Detached Garages and Accessory Structures.
i. “Accessory structures” used solely for parking (two car detached garages or smaller) or limited storage (small, low-cost sheds), as defined in Section
15.68.050, may be constructed such that its floor is below the base flood elevation (BFE), provided the structure is designed and constructed in accordance with the following requirements:
(A)
Use of the accessory structure must be limited to parking or
limited storage;
(B)
The portions of the accessory structure located below the BFE
must be built using flood-resistant materials;
(C)
The accessory structure must be adequately anchored to prevent
flotation, collapse and lateral movement;
(D)
Any mechanical and utility equipment in the accessory structure
must be elevated or floodproofed to or above the BFE;
(E)
The accessory structure must comply with floodplain encroachment provisions in Section
15.68.210; and
(F)
The accessory structure must be designed to allow for the automatic entry of floodwaters in accordance with subsection
(C)(3) of this section.
ii. Detached garages and accessory structures not meeting the above standards
must be constructed in accordance with all applicable standards in
this section.
(Prior code § 152.30)
Since floodways are an extremely hazardous area due to the velocity
of floodwaters which carry debris, potential projectiles and erosion
potential, the following provisions apply:
A. Until
a regulatory floodway is adopted, no new construction, substantial
development or other development (including fill) shall be permitted
within Zones A1-30 and AE, unless it is demonstrated that the cumulative
effect of the proposed development, when combined with all other development,
will not increase the water surface elevation of the base flood more
than one foot at any point within the City of Desert Hot Springs.
B. Within
an adopted regulatory floodway, the City of Desert Hot Springs shall
prohibit encroachments, including fill, new construction, substantial
improvements and other development, unless certification by a registered
civil engineer is provided demonstrating that the proposed encroachment
shall not result in any increase in flood levels during the occurrence
of the base flood discharge.
C. If subsections
A and
B of this section are satisfied, all new construction, substantial improvement and other proposed new development shall comply with all other applicable flood hazard reduction provisions of Article III.
(Prior code § 152.35)