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Oklahoma's Floodplain Management 101

Chapter 4: Floodplain Ordinance Administration

Submerged vehicle on a flooded city street

Chapter 4 Appendix

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So far, this guidebook has provided information on the National Flood Insurance Program and the Oklahoma Floodplain Management Act, included floodplain information provided by FEMA, and detailed the regulatory standards communities must meet to maintain participation in the program. But how do the floodplain management aspects of the NFIP actually work? What steps must a community take to ensure development in the floodplain is not flood-prone?

Chapter 4 describes the development permit system essential to communities to guide and manage floodplain development and discusses the permit record keeping system, the local administrator, enforcement, and variances.

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Development Permit System

The regulations of the NFIP, 44 C.F.R., 60.3, outlining floodplain management criteria for flood-prone areas, state that the community shall "require permits for all proposed construction and other developments including the placement of manufactured homes" within Special Flood Hazard Areas. More importantly, when a community joins the NFIP, then that community's flood ordinance requires the same thing. At this point it is not the NIFP, OWRB, FEMA requirement, it is your requirement. In other words, no construction or development is allowed in a "flood-prone" or an identified "flood hazard" area without a permit from the community. The community may issue a permit after ensuring the proposed development meets its flood damage prevention ordinance as outlined in Chapter 3.

The concept of "development" goes beyond the traditional building permit. Whereas the building permit is concerned with buildings, the development permit's broad scope includes buildings and alterations to landscape (such as excavation or the use of fill) that would affect drainage patterns or the flood-carrying capacity of the watercourse.

The administrator must first ensure that citizens apply for floodplain development permits. Citizens need to know the community has a flood ordinance and that development in the regulatory floodplain requires a permit. To get the word out, the floodplain administrator should start a public awareness campaign, including press releases in the local paper, a booth at the county fair, flood-awareness month proclamations, etc.

In Oklahoma most counties do not require building permits for construction and development. If this is the case, citizens in these communities should complete a notice of intent (NOI) form (see Appendix 4-1) if they plan to develop or construct anything in the community. The NOI is submitted to the floodplain administrator so he/she can determine if the proposed development will fall in or outside the regulatory floodplain. If the proposed development will fall in the floodplain, the floodplain administrator requires the developer to complete the remainder of the permit application. If the proposed development is outside the floodplain, no further action is required. The floodplain administrator should keep a record of all NOIs. This is a very important part of the local floodplain management program.

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When a Permit is Required

A permit is required when building or enlarging a structure, placing a manufactured home, mining, dredging, filling, grading, drilling, excavating, landscaping, building, storing supplies and/or equipment, or repairing roads and bridges within flood hazard areas. In other words, any development, structural or nonstructural, that may affect flooding characteristics or flood damages is required to be permitted.

Specifically, all structural projects (buildings, manufactured homes, storage facilities, dams, dikes, etc.) need a permit. Removal, as well as placement activities, needs a permit depending on their type, magnitude, and location. For example, a street paving project at grade still may alter flood flows or increase flood heights and will require a permit. In addition, a fence may affect flooding and would also require a permit. The storage of large, round hay bales (bridge plugs) should be stored away from the main water channels. Installing a fiber optic cable across a floodplain or directional boring under a creek will require a permit. In summary, any development in the regulatory floodplain requires a floodplain development permit.

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The Permit Application

Anyone wishing to develop in the floodplain must obtain a permit application from the floodplain administrator, fill it out, pay appropriate fees, and submit it for approval before beginning any development activities. Instructions and a development permit application form are provided in Appendix 4-2. This sample building permit could be adopted by the community as a floodplain development permit. Communities may instead adapt their existing permit systems to comply with their flood damage prevention ordinance. Regardless of the form used, the following information must be supplied on a permit application for floodplain development:

  • A complete description of the proposed activity. Enough information must be included so the floodplain administrator can determine whether or not the proposed activity will be safe from flooding and whether it will increase flood hazards elsewhere. At a minimum, there should be plans drawn to scale showing the nature, location, dimensions, and elevations of the area in question; existing or proposed structures, fill, storage of materials, drainage facilities, or any other landscape alterations.
  • The National Geodetic Vertical Datum (NGVD) elevation of the lowest floor (including the basement) of all proposed structures.
  • The NGVD elevation to which any proposed nonresidential structures will be floodproofed.
  • Certification by a registered professional engineer or architect that any floodproofing method to be used meets the community's floodproofing criteria.
  • Base Flood Elevation data for subdivision plats of 50 lots or 5 acres.
  • A description of the extent to which any watercourse (stream, river or drainage ditch) will be altered or relocated.
  • All other required local, state, and federal permits have been obtained.

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Reviewing the Permit Application

Reviewing a permit application is the most important responsibility of the floodplain administrator. A permit review checklist is provided in Appendix 4-3. Floodplain administrators may use the checklist to help them determine if the proposed project meets the criteria of the floodplain ordinance. Several factors that apply to all situations must be taken into consideration when reviewing permit applications. In addition, depending on the type or location of a project, special consideration must be included in the review procedure. The items a local administrator must consider for all approved development and for special considerations are outlined below.

The initial item the floodplain administrator must determine is whether or not the proposed development is in the Special Flood Hazard Area. If this is not obvious, the administrator should obtain the distance in the field between the proposed development site and one or more identifiable points (centerline of a street, a bridge, river channel, etc.). Then, using the map scale, the distance from the identifiable point on the map to where the site is located can be determined.

An example is shown in Figure 4-1. The proposed structure is 200 feet north of where the railroad intersects Lake Avenue and 25 feet east of Second Street. Therefore, it will be located in the Special Flood Hazard Area and must meet the requirements of the floodplain ordinance.

A floodplain administrator cannot properly review an application if it is not complete. The application must have an adequate description of the proposed development, including the elevation of structures, certification of floodproofing methods, and BFE data for subdivision plats. If there is not enough data to determine if the development will be safe from flooding, the applicant must provide more information.

The floodplain administrator must request that additional state, local, or federal permits for the proposed project be acquired, if applicable. Besides the floodplain development permit, these permits may include:

  • Oklahoma State Department of Health - The OSDH issues permits for controlled industrial and solid waste disposal sites; public water supply facilities, including source development; treatment and distribution systems (water supply); and sewage collection and treatment, including land disposal systems.
  • Oklahoma Water Resources Board - The OWRB issues permits for water well drillers, dam construction, and floodplain development on state owned or operated property.
  • Oklahoma Corporation Commission - The OCC issues permits for oil and gas drilling activities.
  • Oklahoma Department of Environmental Quality - The DEQ issues permits for stormwater management for any development of one acre or more.
  • Oklahoma State Historical Preservation Officer - The SHIPO reviews development to ensure no significant archaeological site is disturbed.
  • Oklahoma Department of Mines - The ODOM issues permits for various types of mining.
  • U.S. Army Corps of Engineers - A Section 404 permit is needed to discharge dredged or fill materials into rivers and adjacent wetlands. A Section 10 (River and Harbor Act of 1989) permit is required for any project that may affect the course, location or condition of the navigable capacity of a water body. (Section 10 relates only to the Red, Arkansas, Verdigris, Illinois and Canadian Rivers.)
  • Federal Emergency Management Agency (FEMA) - If a developer is going to change the base flood elevation up or down, a map revision is required.

In summary, when an individual proposes any type of development in a Special Flood Hazard Area (SFHA), a variety of permits may be required. As an example, a sewage lagoon is proposed to be built in a SFHA by Community A. Community A would then need to obtain a permit from the State Health Department, satisfy the requirements of the local flood ordinance and possibly the USACE. For any development in the floodplain, an individual should check with local, state, and federal officials for any permits that may be required.

In order to review a permit application, the floodplain administrator must know what the flood hazard or (BFE) is at the development site. If the floodplain administrator has a Flood Insurance Study with accompanying FIRM or FBFM, BFE data for the development site is readily available. If FEMA has not supplied the community with detailed technical data on the flood hazard, the properly adopted regulations allow the floodplain administrator to use the best available information to determine flood heights to ensure the new development is reasonably safe from flooding. This information may be available from several sources, including but not limited to: Flood Hazard Analyses from the Natural Resource Conservation Service; floodplain information and other reports from the U.S. Army Corps of Engineers (USACE) and U.S. Geological Survey (USGS); or studies done by the Oklahoma Department of Transportation (ODOT) or the Oklahoma Water Resources Board (OWRB). If there are no technical data available, the floodplain administrator must use the best judgment and be guided by existing flood maps and historical flood accounts described by newspaper articles and photographs, or by high water marks on buildings, telephone poles, bridges, or other structures. Also refer to the FEMA website for additional procedures on estimating BFE.

Once the floodplain administrator has the flood hazard data available, by reviewing the description of the proposed project in relation to the flood hazard, measures to make it safe from flooding can be determined. For example, if a FIRM or FBFM shows a BFE of 930 ft NGVD, the proposed structure must have its lowest floor built to an elevation of at least 930 ft NGVD. The floodplain administrator would then recommend that the floodplain board issue a development permit for the development on the condition it is elevated to or above the BFE. In the case of a nonresidential structure in an unstudied community where the lowest floor is proposed below known flood heights, floodproofing measures must be identified in order for the development to proceed. These measures must be certified to or above the estimated BFE by a registered architect or professional engineer.

The floodplain administrator must make sure the proposed activity complies with flood ordinances and meets the standards of the NFIP listed in the previous chapter. The standards address anchoring requirements, construction materials and methods, utilities, subdivisions, encroachments, elevation of the lowest floor, and floodways. In reviewing an application, the key to remember is that the proposed activity itself must be safe from flooding and it must not increase the flood hazard or otherwise negatively impact nearby existing development.

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Special Considerations on Permit Review

If a community has a regulatory floodway delineated on an FBFM or a FIRM and the floodplain administrator determines that the proposed development is located in the floodway, then a permit may not be issued unless the applicant can demonstrate, through detailed technical analysis, that the proposed development will not increase flood heights. Usually, floodway developments are limited to passive open space uses, such as recreation or agriculture. Examples of allowable floodway uses are described in Figure 4-2.

Structures existing in a floodway prior to the floodway identification and designation are grandfathered in and can remain as long as they serve a useful purpose. Minimum requirements for substantial improvement (50 percent of the market value or more) to such structures, however, must be elevated to comply with the floodplain ordinance.

When reviewing applications for development in the floodway, the floodplain administrator's first assumption must be that it will cause some rise in the BFE. The developer is required to prove that the proposed development, along with similar future development assumed by the equal degree of encroachment rule, will not cause any increase in BFEs. The developer provides this proof by hiring a registered professional engineer to analyze the development plans and ascertain if the BFEs will be affected. The developer should use an engineering firm experienced in analyzing and modeling hydrologic and hydraulic data.

Unless the analysis establishes that no rise in the BFE would result, the permit must be denied. Deviation from the no-rise analysis is in violation of the local ordinance and NFIP regulations. The community must retain on file certifications that establish the development in the floodway will not increase the BFE. A copy of the engineer's supporting documentation must be kept with that particular permit record. Any development allowed in the floodway must satisfy the remaining program regulations. For example, structures must be protected to the BFE. Information required of proposed floodway development is listed in Appendix 4-4. An example of permissible floodway development would be a second story addition on a house where the external dimensions of the original house are not altered and the addition's cost is less than 50 percent of pre-construction market value. A floodway development checklist for use by the local floodplain administrator is located in Appendix 4-5.

NFIP regulations permit development in the floodplain within an acceptable limit. This limit allows encroachment in Zone AE with no floodway identified until there is no more than a maximum one-foot rise in the BFE at any point in the community. If a community has not been supplied an FBFM or FIRM that outlines a floodway, the community must review each permit application individually for its compliance with this encroachment standard.

In order to do so, the floodplain administrator must require the permit applicant to provide an engineering analysis of the proposed project's impact (along with all existing and any reasonably anticipated development) on flood heights. The analysis must certify that the cumulative effects of the project's impacts are within the acceptable limit. If it does not, the permit must be denied.

The floodplain administrator must maintain certifying documentation of the project's impact on file. By doing so, the administrator will begin a cumulative collection of hydraulic data for the community's flood-prone area that can be used to review future permit applications.

The floodplain administrator should also be concerned with how the depth and velocity of floodwaters will affect proposed development. It is recommended that flood velocities not exceed two or three feet per second in residential areas. Another standard frequently used is that the safety index achieved by multiplying the depth of water by the velocity (feet x feet/second) not exceed a factor of seven. In nonresidential areas, higher velocities may be acceptable.

When a floodplain administrator reviews a development permit that includes a watercourse alteration (for example realignment or diversion of a stream, ditch or river), the flow carrying capacity of the watercourse must not be diminished (see Figure 4-3). The permit applicant must supply a thorough description (a set of plans and calculations) of the proposed alteration and its effect on flows.

Generally, an applicant should provide a topographic map of the area in question, a comparison of the existing and proposed channel capacities, a description of the proposed alteration, land use of adjacent properties, identification of the project's features and an assessment of the changes it will cause.

An administrator who does not have the technical background to review such descriptions must rely on the community's engineering staff or seek outside professional assistance.

Local floodplain regulations require the floodplain administrator to notify adjacent affected communities and the OWRB of any proposed watercourse alterations. Neighboring local governments and the OWRB have an interest in water resources and activities that affect them. A sample watercourse notification letter is provided in Appendix 4-6.

If the watercourse alteration could change the BFE and footprint of the floodplain a Conditional Letter of Map Change is required (CLOMA). Map changes are addressed later in this chapter.

When there appears to be a conflict between the boundary on the flood map issued by FEMA and actual field conditions, the floodplain administrator must interpret the boundaries of the flood hazard area. The floodplain administrator does not, however, have to determine a particular structure's location on the map for flood insurance purchase requirements for lending institutions. That decision rests with the lender.

NFIP regulations allow nonresidential buildings (commercial structures, garages, warehouses, etc.) the option to floodproof, rather than elevate, as a means of protection from the Base Flood (see Figure 4-4). Floodproofing consists of designing a structure in a way that all parts of the structure located below the BFE are watertight and resistant to flood damage. One method of floodproofing is known as dry floodproofing. This method is described below and illustrated in Figure 4-5.

Dry floodproofing consists of the actual design of a structure providing protection from the Base Flood. The structure must be designed to prevent seepage, collapse or cracking of basement walls, buckling of basement floors, and back-up of water from sewer lines. Walls and floors must be capable of withstanding hydrostatic pressure, and all openings must be located one foot above the BFE. Walls and floors must be made watertight with waterproof seals and coverings used on exterior surfaces. The building must have sufficient weight to resist flotation. Features of dry floodproofing must operate automatically without human intervention. Floodproofing measures on nonresidential structures must be certified by a qualified engineer or architect. The FEMA floodproofing certificate for this purpose is found in Chapter 3.

Another method of floodproofing nonresidential structures under the NFIP is reliant on human intervention. This involves the use of door and window shields as temporary protection from the Base Flood. This method should be used only where adequate flood warning time or devices are present. Extreme caution must be used in designing this floodproofing measure. Generally, door and window shields are not effective for flood depths in excess of three feet and may cause more damage to older structures than they prevent. For instance, boards placed over window openings may prevent rising floodwaters from entering the windows, but rainwater can get behind the shields if the space between it and the wall is not closed or sealed.

Wet floodproofing allows floodwaters to enter the structure by design and to equalize the water pressure on the inside to the water pressure on the outside. The concept here is to have utilities raised above flood levels so that after a flood, only minimal cleanup and repair are necessary.

Any time a nonresidential structure is floodproofed, the design of the structure must be certified by a registered professional engineer or architect, stating that it will provide protection against the Base Flood. A floodproofing certificate must be submitted before the permit application process can be completed (see Appendix 4-7).

Dry floodproofing measures are recognized by the NFIP for flood insurance purposes (lower premium rates), but other types of floodproofing, such as wet floodproofing, are not recognized. Appendix 4-8 lists minimum floodproofing standards.

NFIP regulations usually do not accept floodproofing of residential structures. The lowest floor, including basement, must be elevated to or above the BFE on fill, foundation, or on piers and columns.

Because Oklahoma is located in an area that experiences severe storms (tornadoes, strong winds, hail, etc.), a community may pursue an exception to the "No Basement Rule" from FEMA. Such exceptions are granted from the FEMA National Office upon application and fulfillment of strict requirements. A community receiving an exception to the "no basement" rule must supply sufficient technical data and adopt a floodproofing code before FEMA will consider the exception. The preferred procedure for constructing a storm shelter in the 1% chance floodplain is to require the structure to be floodproofed and obtain a floodproofing certificate. The air vent and entrance must be elevated 1 to 2 feet above the BFE, and the structure must be anchored in the ground so it will not bouy up during the 1% chance flood.

NFIP regulations require a community to obtain and maintain a record of the elevation of the lowest floor of all new or substantially improved structures in the flood hazard area. To comply with this regulation, communities must require the owner or developer of such structures to provide an "Elevation Certification" assuring the structure has been built above the BFE (see Appendix 4-9).

Where the BFE is not known and a subdivision of 50 lots or five acres (whichever is less) is planned, NFIP regulations state that the developer must determine a BFE for each lot and delineate it on the subdivision plat.

For some Oklahoma communities, floodplains make up a significant portion of the land available for subdivision development. Floodplains are attractive for subdivision development because of their location; however, if these subdivisions are improperly developed, they can become a costly burden to the community.

Local governments that approve subdivisions in the floodplain must be careful that flood levels are not increased when these subdivisions are developed. Local governments may be liable where attempts to control flooding are ineffective or aggravate an existing situation.

NFIP regulations have changed the treatment of mobile homes. The term "mobile home" is no longer used; it has been replaced by the term "manufactured home". Manufactured homes are now treated as conventional homes, and as such, must be elevated above the BFE when located in the identified floodplain.

Manufactured homes, for floodplain management purposes, include park and travel trailers and similar vehicles that are placed on a site for a period of more than 180 days. Past provisions that allowed replacement, new placement or substantial improvements of manufactured homes in existing manufactured home parks or subdivisions without elevation are now eliminated. New or replacement manufactured homes on lots in the floodplain must be elevated above the BFE and anchored to permanent foundations. For further information regarding placement and anchoring, see Chapter 3.

Manufactured homes that have been continually located in the same floodplain location are affected by this rule change only if they are moved or replaced. This NFIP change will enable community officials to work closer with manufactured home parks and subdivisions located within their community's floodplain.

Only licensed installers can install manufactured homes in Oklahoma.

AO-Zones are areas subject to shallow flooding (one to three feet) resulting from sheet flow conditions. Because no BFE is provided for AO-Zones, NFIP regulations require that residential structures in these areas must have the lowest floor (including the basement) elevated above the highest adjacent grade, at least as high as the depth number specified on the FIRM. If no depth number is indicated, a two-foot flood protection level is required. Nonresidential structures must be elevated or floodproofed above the highest adjacent grade to the depth number specified on the FIRM.

The highest adjacent grade means the highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure. Figure 4-6 illustrates how a structure would need to be elevated in a Zone AO, Depth 2.

AH-Zones are those areas having shallow and/or unpredictable flow paths between one and three feet. These are usually areas subject to ponding. When AH- and AO-Zones are designated, adequate drainage paths around structures are required to guide floodwaters away from these structures. Only a small number of communities in Oklahoma have AO- or AH-Zones mapped.

If the permit application is complete and accurately describes the development, the floodplain administrator should then recommend the floodplain board approve the permit. If the floodplain board finds the development will be built in compliance with the floodplain ordinance, the floodplain board should approve it by simply signing the permit application. The floodplain administrator would then provide a copy to the applicant. Also the floodplain administrator should provide the applicant a bright colored card stock permit card to post at the development site. An example is provided in Appendix 4-10.

If a permit application is incomplete, it should not be approved. Additional information should be requested from the applicant. It is recommended that no permit application go before the floodplain board for approval until the floodplain administrator has thoroughly reviewed it and is absolutely certain it complies with the flood damage prevention ordinance.

Some floodplain administrators may choose to review and approve the permit application without any floodplain board intervention. Caution should be exercised if this is the case. It is highly recommended that some form of check and balance system be implemented in the application review and approval process. The floodplain board is an essential part of a community's floodplain management program.

If the applicant chooses to blatantly violate the floodplain ordinance and not work with the floodplain administrator, the floodplain board may have to deny the permit and explain to the applicant why it was denied. A sample denial letter is found in Appendix 4-11.

An applicant who is denied a permit has three options:

  1. Redesign the development so that it meets the standards of the NFIP;
  2. Appeal the decision to the appropriate governing body (if the applicant believes the floodplain board is in error); or
  3. Request a variance to the ordinance (if the applicant believes the ordinance places an undue hardship on the property)

If a developer has already commenced construction and chooses not to work with the floodplain administrator, the administrator may then issue a cease and desist letter and post a notice of violation at the development site. Appendix 4-12 provides an example of a violation notice poster.

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A variance, as defined by the Federal Emergency Management Agency, is a granting of relief from the requirements of a community's floodplain ordinance, permitting construction in a manner that would otherwise be prohibited by the ordinance. Section 60.6(a) of National Flood Insurance Program regulations contains provisions for variance" allowed as a part of community floodplain management. If a floodplain management study has been completed for a community, its floodplain ordinance may contain a section allowing variances. The Variance Guide found in Appendix 4-13 explains in detail what type of development constitutes a legal variance. A legal variance is dependent on the physical site characteristics of the development property.

Important points to remember about variances:

  • Variances must meet the objectives of sound floodplain management (Appendix 4-14 contains a variance checklist).
  • If a pattern of variance exists (obtained from the biennial report sent to FEMA by the floodplain administrator), FEMA will investigate the circumstance under which the variances were granted.
  • Variance should be granted only in unique physical hardship situations.
  • Variance should never be granted for structure to be built below the identified Base Flood Elevation.

It appears the only time variances could be safely used is prior to an impending map change. The map change would remove the development area from the floodplain. The variance, in this instance, would buy time for the structure, which under the new map, would be allowable development.

It should be noted that the granting of a variance in the floodplain is a floodplain board decision. The best advice concerning variances is DON'T USE THEM! While the impact of a single variance on flood hazards may not be significant, the cumulative impact of several variances may be severe.

If a developer, however, requests a variance, the floodplain board should have a consistent and fair policy to deal with such requests. Variances can be handled through a board of adjustment or the governing body of the county or municipality where no board of adjustment exists.

Regarding variances, NFIP regulations list two important documentation requirements regarding variances:

First, the granting of a variance does not lessen or waive any insurance premium rates. Consequently, when a variance is granted, the floodplain administrator must provide written notification to the applicant that a project granted a variance is not exempt from insurance requirements. In some instances, a variance may result in increased insurance premium rates that could go as high as $25 per $100 of coverage. A sample "Variance" notification letter is found in Appendix 4-15.

Secondly, any floodplain board granting a variance must maintain a record of all variance actions. This would include the justification for granting the variance, a record of the appeals proceedings and copy of the written notification referred to above. These records are reviewed during CAC and CAV visits.

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Record Keeping

Record keeping is an extremely important part of a floodplain board's and floodplain administrator's responsibility when participating in the NFIP. The following records must be kept on file and open for public inspections:

A complete and up-to-date copy of the floodplain ordinance, the flood map (FBFM or FIRM) and the Flood Insurance Study should be on hand. If a study has not been completed, the community should obtain and maintain the best flood hazard data available for the area and use it in guiding floodplain development.

NFIP regulations specifically require that communities obtain and maintain the elevation of the lowest floor (including the basement) of all new or substantially improved structures in the Special Flood Hazard Area. For floodproofed structures, the elevation to which they have been floodproofed must be obtained and recorded. Floodplain administrators must require developers to provide elevation and flood proofing certifications to meet this NFIP requirement.

A project file containing the following items should be kept for each development permit application:

  • A copy of the permit application;
  • A copy of the permit review checklist;
  • A copy of all the engineering data (i.e., plans and specifications and hydraulic and hydrologic analyses used to document a development's compliance with the NFIP floodway and encroachment standards.
  • A copy of the engineering analyses submitted for watercourse alteration projects;
  • Copies of all pertinent correspondence relating to the project;
  • Any variance or appeals proceedings;
  • Documentation of inspections of the development;
  • Base Flood Elevation data for subdivisions of five acres, 50 lots or larger;
  • Elevation for floodproofing certifications indicating the lowest floodproof floor elevation; and
  • Elevation certificate indicating the lowest floor elevation and lowest adjacent ground elevation.

A file should be kept for the Biennial Reports that are submitted to FEMA. The floodplain administrator may want to keep the following information in this file:

  • Elevation certificates indicating the lowest floor elevation and lowest adjacent ground elevation.
  • Copies of previous years' annual and biennial reports;
  • A running total of permits and/or variances granted in the flood hazard area;
  • Maps of new annexations or other boundary changes;
  • Census data; and
  • Records of any major natural or man-made changes affecting flooding patterns.

The Biennial Report will be easy to complete if this information is readily available.

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Amendments and Revisions to Flood Insurance Rate Maps

Although FEMA uses the most accurate flood hazard information available, limitations of scale or topographic definition of the source maps used to prepare the FIRM, as well as changes in flood conditions and dynamics in general, may cause small areas that are at or above the flood elevation to be inadvertently shown within the SFHA boundaries. Also, the placement of fill may elevate small areas within the SFHA boundaries to an elevation at or above the flood elevation. When this happens, structures or parcels of land may be inadvertently included in the SFHA on the FIRM. When fill is added to Zone A or AE, a certificate of fill is required (see Appendix 4-16).

For such situations, the property owner and/or community may apply for a Letter of Map Amendment (LOMA) or a Letter of Map Revision based on fill (LOMR-f). LOMAs and LOMR-Fs are documents issued by FEMA that officially remove a property and/or structure from the SFHA. Such amendments or revisons cannot adversely impact the existing floodway or floodway delineations of the 100-year flood.

  • Letter of Map Amendment (LOMA): The map can be changed if the building is shown to be on ground higher than the 100-year flood elevation (see Figure 4-7). The lowest adjacent grade is compared to the 100-year flood elevation for buildings built before the first FIRM was published (pre-FIRM buildings). For newer structures (post-FIRM buildings), the lowest floor (including basement) is also compared to the 100-year flood elevation. For vacant lots, it must be shown that the lowest elevation within the boundaries of the property is above the 100-year flood elevation. Otherwise, a Conditional Letter of Map Amendment or CLOMA can be requested. To make a FIRMette using Catalog Search, see Appendix 4-17.
  • Letter of Map Revision Based on Fill (LOMR-F): A LOMR-F removes a structure or property from 100-year floodplain based on the placement and proper compaction of fill outside the floodway. For buildings: the lowest adjacent grade and the lowest floor (including basement) must be above the 100-year flood elevation. For undeveloped properties: the lowest lot elevation must be above 100-year flood elevation. The participating community must also determine that the land and any existing or proposed structures to be removed from the SFHA are "reasonably safe from flooding".
  • A Letter of Map Revision (LOMR) may be requested based on scientific challenges to the flood elevations, to incorporate new data that became effective after the construction of a flood control project, to change the floodplain or floodway boundaries and to include other new flood data (see Figure 4-8).

Letter of Map Revision (LOMR): A LOMR (see Figure 4-9) is normally based on revised hydraulic modeling and usually will not involve specific lots, properties or structures. Because it will revise official regulatory elevations or floodways, a request for a LOMR must have the approval of the community.

NFIP maps are not changed based on proposed projects. However, an applicant may request a Conditional Letter of Map Revision (CLOMR) or a Conditional Letter of Map Revision based on Fill (CLOMR-F) based on proposed plans. A Conditional Letter of Map Amendment (CLOMA) can be requested for a vacant lot. Property owners are cautioned that these conditional letters merely provide comment on the proposed plan and do not amend the map. A LOMR, LOMR-F, or LOMA will still be required to officially change the NFIP map.

It should be noted that the FIRM will not be reprinted when a LOMA, LOMR or LORM-F is granted. Because such letters of change officially amend or revise the effective NFIP map, it is a public record that the community must maintain. Any letters of map changes should be noted on the community's master flood maps and filed by panel number in an accessible location. This will help ensure that changes are not forgotten or overlooked.

The following packages containing forms and instructions for requesting the respectively listed letters of change and information on associated fees can be found on FEMA's website:


MT-2: LOMR, CLOMR, Physical Map Revision

MT-EZ: LOMA for a single lot, LOMR-F for a single lot for a homeowner

The MT-EZ is the shortest and simplest of the forms to complete, but a land surveyor, professional engineer, or landscape architect is still needed to certify elevation data. The MT-EZ form is available on the FEMA Web site. The MT-EZ contains detailed information regarding how to get a LOMA and how to determine the status of a map change request, as well as other map change issues.

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