Appendix A. CONDITIONS AND CRITERIA FOR MAP REVISIONS OF FEDERAL EMERGENCY MANAGEMENT AGENCY
Federal Emergency Management Agency
Washington, D.C. 20472
CONDITIONS AND CRITERIA FOR MAP REVISIONS
A.
Introduction
This document describes the conditions and criteria for revising a Flood Insurance Study (FIS) under Part 65 of the National Flood Insurance Program (NFIP) regulations. The Federal Emergency Management Agency (FEMA) recognizes that FISs may require revision due to new information becoming available or through physical changes in flood plains. This document defines the situations that fall under Part 65 of the NFIP regulations and describes the procedures for correcting or updating Flood Insurance Rate Maps (FIRMs) and Flood Boundary and Floodway Maps (FBFM(s).
B.
Definitions
A Letter of Map Amendment (LOMA) issued under Part 70 of the NFIP regulations indicates whether or not a structure(s) or proposed structure(s) is located in a Special Flood Hazard Area (SFHA) as shown on a FIRM or Flood Hazard Boundary Map (FHBM). A LOMA removes a property from the SFHA and thereby makes inapplicable the Federal requirement for the purchase of flood insurance. For more information regarding LOMAs, refer to "Conditions and Criteria for Letters of Map Amendment."
A Conditional Letter of Map Revision , or belief letter, issued under Part 65 of the NFIP regulations is FEMA's comment on the effectiveness or impacts of a proposed flood control project or flood plain modification. It is based on FEMA's review of the proposed project and states that were the proposed project built as designed, it would be cause for a map revision.
A Letter of Map Revision (LOMR) can be issued under Part 65 of the NFIP regulations as an expeditious means of revising a FIRM or FBFM. The LOMR gives a detailed description of the Base Flood Elevation (BFE) and graphic changes that will be made to the SFHA currently delineated on the effective FIRM and/or FBFM. LOMRs involving BFE changes are always succeeded by a physical map revision.
A Physical Map Revision under Part 65 of the NFIP regulations involves changing and republishing the existing FIRM and/or FBFM to reflect any updated condition. Valid LOMAs and LOMRs are incorporated into map revisions.
C.
Reasons for Revision
FEMA will revive an effective FIS to reflect new information which shows the original FIS to be incorrect and to reflect physical changes which invalidates the original FIS analyses or presentation of data. Updated or corrected topographic mapping, hydrologic data, or hydraulic data constitute new information which may warrant a revision. Flood protection projects and any form of topographic alterations (cut and fill) constitute physical changes which may also warrant a map revision.
D.
General Revision Policy
Within the statutory criteria established for appeals, revision requests will be evaluated based on the possession of knowledge or information indicating that the effective elevations are scientifically or technically incorrect. In certain situations where new information shows mathematical or measurement errors in the original FIS, FEMA will accept the responsibility for revising the FIS provided the requestor submits the basic data necessary to correct the problem. Where revision requests are based on the application of alternative methods, appellants are required to demonstrate that the new analyses result in more correct estimates of base flood elevations, thus demonstrating that FEMA's estimates are incorrect. In these situations, where a revision request is being made based on improved data, methods, or applications, the community (or requestor through the community) must accept responsibility for providing all data and analyses necessary to update the FIS.
If a physical change resulting from development warrants a revision to the existing analyses, FEMA will not undertake this new technical analysis. The requestor, through the community, must accept responsibility for providing all data and analysis necessary for updating the FIS.
E.
Community Map Revision Requests
The map revision process cannot be initiated without the community's endorsement since it is the community that adopts the effective FIS. Therefore, any individuals requesting a change to the FIS, must do so through the community. The community, in turn, may support the request and forward the information to FEMA for evaluation. FEMA will review the request to ascertain that the following conditions are met before evaluating the revision request.
Condition Number 1
The community must endorse the revision request and demonstrate preparedness to accept responsibility for the operation and/or maintenance of any structural measures (e.g. channel improvements or levees) involved. The request submittal should include the following:
1.1 A statement that the community endorses the revision request.
1.2 If the basis for the revision request is a channel modification, the completion of a dam, levee, or any other structural measure, evidence is required to demonstrate the design is adequate and that maintenance and operation provisions, where applicable, have been made.
a.
For a channel modification or similar structural measure, the community is responsible for maintenance of the channel.
b.
For a levee, the community must develop and officially adopt a formal maintenance and operation plan that describes the type and frequency of the maintenance activities that will be performed and the operation of any closure.
1.3 The submittal must indicate that, where necessary, state approval of the revision has been obtained.
Condition Number 2
If the revision request is based on information showing a mathematical or measurement error in the original analysis, the submittal must include the followings
2.1 Documentation that identifies the specific source of the error.
2.2 A written description of the new information and how it differs from the existing FIS information.
2.3 Basic data supporting the revision request to enable FEMA to revise the FIS. In most cases, this data must be certified by a registered professional engineer or licensed land surveyor. Updated topographic maps, revised community boundary maps including annexation ordinances, and channel, dam, or bridge structure plans which illustrate the correct dimensions are examples of the basic data required.
Condition Number 3
If the revision request is based on improved application of hydrologic, hydraulic, or other methods, or use of better data in applying such methods, the requestor must submit the following:
3.1 Documentation that identifies the error in the application or in the inferior data in the original analysis and supports why the application is incorrect or the data is inferior.
3.2 Engineering analyses applying the same basic methods utilized by FEMA but with the changes itemized.
3.3 Alternative engineering analyses utilizing the methods or assumptions determined to be correct.
3.4 Background technical information which supports the requestor's changes as being more correct.
3.5 Certification by a registered professional engineer or licensed land surveyor of the correctness of any alternate data utilized or measurements made.
3.6 Documentation of all locations where the requestor's base flood elevations are different from FEMA's.
All engineering analyses performed must substantiate that the revised hydrologic or hydraulic analyses meet FEMA requirements as well as any state or community requirements.
F.
General Technical Guidance
Flood plain revisions should be based on the hydraulic model used to develop the flood profile and flood boundaries currently in effect. The community should request, through the FEMA Regional Office, a copy of the input data used in the computer model for its effective FIS. Where the input data representing the original hydraulic model is unavailable, or where a technically superior model can be used, an approximation should be developed. A new model should be established using the original cross section topographic information, where possible, and the discharges contained in the FIS which established the original BFEs. The model must use the same effective flow areas as established in the original analysis and must be calibrated to reproduce the original base flood elevations within 0.1 foot. Any differences between the new analysis and the original profile must be justified on an engineering basis.
After the model has been checked and matches the original base flood elevations, the model can be modified for new flood plain runs. The analysis will be accomplished as specified for the following conditions:
Discharge Decreases. Hydraulic analyses may be revised when a base flood discharge decreases as a result of structural improvements, such as the construction of a flood control dam or other significant retention facilities. Hydraulic analyses should not be revised based on a computed discharge reduction which results from changed methodology or longer stream gage records, unless the change is statistically significant. The statistical significance criteria are discussed in Section 2-6 "Hydrologic Analyses" of FEMA's Guidelines and Specifications for Study Contractors (dated September 1985). If it is evident that the change is statistically significant, the original hydraulic model should be rerun, changing only the discharges. In cases where the statistical significance test does not apply, a determination by a state or Federal agency that the change is significant may be accepted as a basis for a map revision.
Discharge Increases. If watershed conditions have resulted in a significant (defined as above) increase in discharge, the original hydraulic model must be run with the increased discharges.
Channel Modification. The original hydraulic model will be modified to include the channel modification, and any other encroachment occurring subsequent to the original flood plain delineation.
In all situations, the revised hydraulic analysis should be modified to include current conditions as well as any encroachment to the flood plain that may have occurred since the original model was developed. The revised hydraulic analysis should also include a zone determination, and if only a portion of the existing hydraulic analysis is revised, the upstream and downstream portions of the revised analysts should coincide with the effective FIS profiles, i.e., hydraulic calculations should be continued for a great enough distance upstream and downstream of the revised area until water-surface elevations coincide with those in the effective FIS.
The submittal must include the technical data that enables FEMA to determine whether the flood plain revision meets FEMA's requirements. The submittal must include the followings
• A copy of the printout for the original hydraulic computer model representing the 100-year flood profile run for conditions existing at the time the currently effective hydraulic analysis was developed. The printout must include full input and output listings.
• A copy of the printout from the hydraulic computer model representing the new 10-, 5-, 100-, and 500-year profiles. The model should be the same as that used in the preceding item, but modified to include any channel modification, fill or other encroachment that may have occurred in the flood plain since the original flood plain was delineated.
• Delineation of the 100- and 500-year flood boundaries and the location and alignment of cross sections and flow line used in the hydraulic model. This information should be shown on a map of suitable scale and topographic definition to provide reasonable accuracy.
• A copy of the currently effective flood profiles showing the existing and the revised flood elevations.
• Certification from a registered professional engineer that the physical parameters used in the proposed flood boundary delineation represent actual conditions and that the standards contained in these "Conditions and Criteria" are met.
When a map is revised as a result of a new hydraulic analysts, the effect of the revised hydraulics on the floodway must also be considered. If a revised floodway analysis is necessary, the community should refer to the "Conditions and Criteria for Floodway Revisions" for additional information that will be required.
G.
FEMA Response to Map Revision Request
FEMA will evaluate a request from the community for a revision and respond by one of the following means:
(1)
A preliminary copy of the revised FIS will be sent to the community for their review. If the revision involves BFE changes or the establishment of new BEEs, FEMA will initiate a 90-day Appeals Period. Upon review and resolution of any comments and/or appeals received, FEMA will issue a new effective FIS which will be sent to all previous recipients of the maps.
(2)
Send a Letter of Map Revision (LOMR) to the community stating that the review of the submitted material has resulted in an official map revision but that a physical map revision is not warranted at this time. The LOMR will give a detailed description of the BFE and graphic changes that have been made to the SFHA currently delineated on the effective FIS. The material, including a copy of the maps showing the revised information, will be filed for incorporation at a later time into a physical map revision. The approved map revision copies will be dated. Since it is possible that FEMA has responded to a map revision request in this manner, all FIS users are encouraged to contact the community before proceeding with plans for development within the flood plain areas. LOMRs that result in an increase in BEE will also be preceded by a 90-day appeals period. An appeals period for a LOMR which only decreases BFEs will be provided subsequent to the issuance of the WMR.
(3)
Send a letter to the community with a copy to any other requestor stating that the submitted material is not adequate to make an evaluation and offer them the option of submitting additional information.
(4)
Send a Letter to the community with a copy to any other requestor stating that the submitted material appears to justify a map revision, but because not enough information was submitted the community will be placed on a list for restudy consideration, as funds permit, unless the community can submit additional information.
(5)
Send a letter to the community with a copy to any other requestor stating that the submitted material does not substantiate their request for a map revision and that the file will be closed unless the community can submit additional information to substantiate their request.
H.
Submittal of Material
Submit material to the FEMA Regional Office. The Regional Office will review material for completeness, concur with the proposed changes, approve any maintenance ordinances, and forward the necessary material to FEMA Headquarters.
FEMA Headquarters will review the hydrologic/hydraulic backup material, engineering design, and any plans of operation and maintenance (where appropriate), request additional information as necessary, then respond to the community by means of the appropriate action defined under Section F above.
To obtain further information on the conditions and criteria for map revisions, communities are encouraged to contact the appropriate FEMA Regional Office or FEMA Headquarters in Washington, D.C., at (202) 287-0700, prior to requesting a map revision.
FEMA REGIONAL OFFICES
Region I
(Connecticut, Maine, Massachusetts, New Hampshire Rhode Island, and Vermont)
Federal Emergency Management Agency
Natural and Technological Hazards Division
J. W McCormack Post Office and Courthouse Building
Room 462
Boston, Massachusetts 02109Region II
(New York, Puerto Rico, New Jersey, and Virgin Islands)
Federal Emergency Management Agency
Natural and Technological Hazards Division
26 Federal Plaza, Room 19-100
New York, New York 10278Region III
Delaware, District of Columbia, Maryland, Pennsylvania, Virginia, and West Virginia)
Federal Emergency Management Agency
Natural and Technological Hazards Division
Liberty Square Building (Second Floor)
105 South Seventh Street.
Philadelphia, Pennsylvania 19106Region IV
(Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, and Tennessee)
Federal Emergency Management Agency
Natural and Technological Hazards Division
1371 Peachtree Street, N.E.
Suite 736
Atlanta, Georgia 30309Region V
(Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin)
Federal Emergency Management Agency
Natural and Technological Hazards Division
300 South Wacker Drive
(24th Floor)
Chicago, Illinois 60606Region VI
(Arkansas, Louisiana, New Mexico, Oklahoma, and Texas)
Federal Emergency Management Agency
Natural and Technological Hazards Division
Federal Center
800 North Loop 288
Denton, Texas 76201-3698Region VII
(Iowa, Kansas, Missouri, and Nebraska)
Federal Emergency Management Agency
Natural and Technological Hazards Division
Federal Office Building
911 Walnut Street
Kansas City, Missouri 64106Region VIII
(Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming)
Federal Emergency Management Agency
Natural and Technological Hazards Division
Denver Federal Center
Box 25267
Building 710
Denver, Colorado 80225-0267Region IX
(Arizona, California, Hawaii, and Nevada)
Federal Emergency Management Agency
Natural and Technological Hazards Division
Presidio of San Francisco
Building 105
San Francisco, California 94129Region X
(Alaska, Idaho, Oregon, and Washington)
Federal Emergency Management Agency
Natural and Technological Hazards Division
Federal Regional Center
130 228th Street, S.W.
Bothell, Washington 98021-9796