[Code of Federal Regulations]
[Title 44, Volume 1]
[Revised as of October 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 44CFR65.13]

[Page 336-337]
 
              TITLE 44--EMERGENCY MANAGEMENT AND ASSISTANCE
 
 CHAPTER I--FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND 
                                SECURITY
 
PART 65_IDENTIFICATION AND MAPPING OF SPECIAL HAZARD AREAS--Table of Contents
 
Sec.  65.13  Mapping and map revisions for areas subject to alluvial fan 

flooding.

    This section describes the procedures to be followed and the types 
of information FEMA needs to recognize on a NFIP map that a structural 
flood control measure provides protection from the base flood in an area 
subject to alluvial fan flooding. This information must be supplied to 
FEMA by the community or other party seeking recognition of such a flood 
control measure at the time a flood risk study or restudy is conducted, 
when a map revision under the provisions of part 65 of this subchapter 
is sought, and upon request by the Administrator during the review of 
previously recognized flood control measures. The FEMA review will be 
for the sole purpose of establishing appropriate risk zone 
determinations for NFIP maps and shall not constitute a determination by 
FEMA as to how the flood control measure will perform in a flood event.
    (a) The applicable provisions of Sec. Sec.  65.2, 65.3, 65.4, 65.6, 
65.8 and 65.10 shall also apply to FIRM revisions involving alluvial fan 
flooding.
    (b) The provisions of Sec.  65.5 regarding map revisions based on 
fill and the provisions of part 70 of this chapter shall not apply to 
FIRM revisions involving alluvial fan flooding. In general, elevations 
of a parcel of land or a structure by fill or other means, will not 
serve as a basis for removing areas subject to alluvial fan flooding 
from an area of special food hazards.
    (c) FEMA will credit on NFIP maps only major structural flood 
control measures whose design and construction are supported by sound 
engineering analyses which demonstrate that the measures will 
effectively eliminate alluvial fan flood hazards from the area protected 
by such measures. The provided analyses must include, but are not 
necessarily limited to, the following:
    (1) Engineering analyses that quantify the discharges and volumes of 
water, debris, and sediment movement associated with the flood that has 
a one-percent probability of being exceeded in any year at the apex 
under current watershed conditions and under potential adverse 
conditions (e.g., deforestation of the watershed by fire). The potential 
for debris flow and sediment movement must be assessed using an 
engineering method acceptable to FEMA. The assessment should consider 
the characteristics and availability of sediment in the drainage basin 
above the apex and on the alluvial fan.
    (2) Engineering analyses showing that the measures will accommodate 
the estimated peak discharges and volumes of water, debris, and 
sediment, as determined in accordance with paragraph (c)(1) of this 
section, and will withstand the associated hydrodynamic and hydrostatic 
forces.
    (3) Engineering analyses showing that the measures have been 
designed to withstand the potential erosion and scour associated with 
estimated discharges.
    (4) Engineering analyses or evidence showing that the measures will 
provide protection from hazards associated with the possible relocation 
of flow paths from other parts of the fan.
    (5) Engineering analyses that assess the effect of the project on 
flood hazards, including depth and velocity of floodwaters and scour and 
sediment deposition, on other areas of the fan.
    (6) Engineering analyses demonstrating that flooding from sources 
other than the fan apex, including local runoff, is either insignificant 
or has been accounted for in the design.

[[Page 337]]

    (d) Coordination. FEMA will recognize measures that are adequately 
designed and constructed, provided that: evidence is submitted to show 
that the impact of the measures on flood hazards in all areas of the fan 
(including those not protected by the flood control measures), and the 
design and maintenance requirements of the measures, were reviewed and 
approved by the impacted communities, and also by State and local 
agencies that have jurisdiction over flood control activities.
    (e) Operation and maintenance plans and criteria. The requirements 
for operation and maintenance of flood control measures on areas subject 
to alluvial fan flooding shall be those specified under Sec.  65.10, 
paragraphs (c) and (d), when applicable.
    (f) Certification requirements. Data submitted to support that a 
given flood control measure complies with the requirements set forth in 
paragraphs (c) (1) through (6) of this section must be certified by a 
registered professional engineer. Also, certified as-built plans of the 
flood control measures must be submitted. Certifications are subject to 
the definition given at Sec.  65.2.

(Approved by the Office of Management and Budget under control number 
3067-0147)

[54 FR 33551, Aug. 15, 1989]