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Q: What is the 100-year floodplain?
A: The 100-year floodplain is defined as the area that would be covered by floodwater during a 100-year storm event. In stormwater managements, floods are classified by statistical probability of occurrence. When we speak of a 100-year flood, we are referring to a flood event that has a one percent chance of occurring in any given year. The magnitude of a 100-year flood is determined from historical data and precipitation patterns within the watershed.
Floodplain boundaries vary along a channel depending on such factors as topography, soils and vegetation, the size of the watershed and the condition of the channel. These boundaries may also change over time as the watershed is developed or the channel is altered. In addition, the floodplain may be redefined as new or revised statistical data becomes available.
Q: What is a floodway? What does it mean when homes or land are in the floodway?
A: A floodway is the area of the floodplain that should be kept free of obstructions to allow floodwaters to move downstream. Rivers and streams where FEMA has prepared detailed engineering studies may also have designated floodways. For most rivers and streams, the floodway is where the water is likely to be the deepest and fastest. Placing fill or buildings in a floodway may block the flow of water and increase flood heights. Because of this, your community will require that you submit engineering analyses before it approves permits for development in the floodway.
If your home or other structure is already in the floodway, you may want to consider what you will do if it is damaged. If the structure is substantially damaged (the costs to repair equal or exceed 50 percent of the market value of the building) your community will require that you bring it into compliance. In most cases, this means you will have to elevate it above the base flood elevation. Because placing fill dirt in the floodplain can make flooding worse, you'll probably have to elevate the structure on columns, pilings or raised foundation walls. If your land is large enough to have a home site outside of the floodway or even out of the floodplain, you may want to think about moving your home to a safer location.
Q: What do I need to know if my building is in the floodplain?
A: Buildings in special flood hazard areas shown on FIRMs may be damaged when flooding occurs. Some buildings flood frequently, while others get damaged by only the more severe events.
If your home is in the 100-year (one percent annual chance) floodplain, it has a 26 percent chance of getting flooded over a 30-year period. It is approximately five times more likely to be damaged by flood than by a severe fire.
You should know that usually you can get flood insurance, if available, by contacting your regular homeowner's insurance agent. FEMA and the Flood Control District recommend that everyone in special flood hazard areas buy flood insurance. If you buy a home or refinance your home, your mortgage lender or banker may require flood insurance. Even if not required, however, it is a good investment especially in areas that flood frequently or where flood forces are likely to cause major damage.
You should also know that your community may require permits for remodeling, improving, expanding or rebuilding your home or other structure. In order to reduce long-term flood damage, the National Flood Insurance Program (NFIP) requires that buildings that are substantially improved or substantially damaged become compliant. This means if the cost of the improvements or repairs is more than 50 percent of the market value of the building, you will have to make it compliant with the rules for floodplain construction. Usually, this means lifting it off the foundation and elevating it above the predicted flood level. If you carry a flood insurance policy and have major flood damage, you may be eligible for up to $20,000 to help pay for the cost of this work.
Q: Can floodway or floodplain boundaries be changed?
A: Under current Floodplain Regulations, the channel and/or adjacent lands may be modified to reduce the water surface elevation during a 100-year flood, thus narrowing the floodway boundaries.
Q: What is fill and how does it affect the floodplain?
A: For the National Flood Insurance Program (NFIP), fill refers to soil that is brought in to raise the level of the ground. Depending on where the soil is placed, fill may change the flow of water or increase flood elevations. Fill may be used to elevate a building to meet the NFIP requirements. Sometimes fill is combined with other methods of elevation such as pilings or foundation walls. Placement of fill requires a Floodplain Use Permit.
Q: The Flood Insurance Rate Map (FIRM) shows that my lot is in the mapped floodplain, but my house sits on higher ground. I believe I shouldn't be shown in the floodplain. What are FEMA's requirements for being removed from the 100-year flood hazard area?
A: To be removed from the floodplain shown on the FIRM, a structure must be on land that is not subject to flooding by a 100-year flood. Remember, more severe floods can and do happen, so even if your home is found to be on high ground, it may still be damaged by an extreme flood event.
If your lot or building site is on natural ground that is higher than the Base Flood Elevation (BFE) shown on the FIRM, then you may request a Letter of Map Amendment (LOMA). To support your request, you will need to have a land surveyor determine the elevation of the ground next to your building and complete an Elevation Certificate. If the ground is higher than the BFE, then FEMA will issue a LOMA. With a LOMA, your lender may choose to not require flood insurance.
If your home was built on fill that was placed after the FIRM was prepared, you may request a Letter of Map Revision Based on Fill (LOMR-F). As with a LOMA, an Elevation Certificate will need to be completed by a land surveyor. If the filled ground is higher than the BFE, and if you do not have a basement, then FEMA may issue a LOMR-F and your lender may choose to not require flood insurance.
Q: How do I get a revision to the Flood Insurance Rate Map (FIRM)?
A: A revision to the FIRM may be requested by completing and submitting the appropriate portions of the application/certification forms package titled "Revisions to National Flood Insurance Program Maps" (FEMA Form 81-89 Series), and the required supporting information. Click on the links below for the respective FEMA application forms:
MT-EZ
MT-1
MT-2
If you have questions, please call the Flood Control District at (602) 506-1501 and ask to speak with a Floodplain Representative.
Q: Where should I send my map revision request?
A: Revision requests should be sent to the appropriate FEMA regional office.
Q: Do I need to submit a fee with my map revision request?
A: In most cases, yes. To ensure full reimbursement of funds expended to review and process most map change requests, the Federal Emergency Management Agency (FEMA) established a standard fee schedule. The fee schedule is published periodically in the Federal Register and appears in the application/certification forms package.
Q: How long does it take to get a map revision?
A: FEMA typically responds in less than 30 days, and must respond to a revision request within 90 days of receipt of the application/certification forms and the supporting information. The response may be a determination, a request for additional information, or a statement that additional time will be required to complete the processing of the request.
Q: How can I expedite my request?
A: Because FEMA receives many requests, they are processed on a first-come, first-served basis. The best way to get a timely response is to make sure the forms and supporting information are complete.
Q: When should I request a conditional map revision?
A: FEMA's review and comment on a project that is proposed within the Special Flood Hazard Area is referred to as a Conditional Letter of Map Revision (CLOMR). A CLOMR comments on whether the proposed project meets the minimum floodplain management criteria of the National Flood Insurance Program (NFIP) and, if so, what revisions will be made to the community's NFIP map if the project is completed as proposed.
There are only two situations where NFIP regulations require a CLOMR to be obtained from FEMA before a project can be built. The first is for a project on a stream or river that has been studied through detailed hydrologic and hydraulic analyses, and for which base flood elevations have been specified, but a floodway has not been designated. If the community proposes to allow development that would result in more than a one-foot increase in the base flood elevation, a CLOMR must first be obtained.
The second situation requiring a CLOMR is for a project on a stream or river for which detailed analyses have been conducted, and base flood elevations and a floodway have been designated. If the community proposes to allow development totally or partially within the floodway that would result in any (greater than a zero) increase in the base flood elevation, a CLOMR must be obtained.
Although the two situations described above are the only requirements to obtain a CLOMR prior to permitting development, FEMA will review and comment and, if appropriate, issue a CLOMR for any proposed project when requested by a participating community. All requests for CLOMRs must be supported by detailed flood hazard analyses prepared by a qualified professional engineer. The specific data and documentation requirements are contained in Part 65 of the NFIP regulations and in FEMA's application/certification forms (MT-2). To defray costs to NFIP policyholders, FEMA charges fees to recover review costs. Specific information on the fee schedule and exemption requirements is contained in the MT-2 forms.
Q: Which elevation datum do I use?
A: Flood Insurance Rate Maps (FIRMs) reference the elevation datum used to compute flood elevations. In completing elevation certificates, the same elevation datum as that shown on the FIRM must be used to compute lot and/or structure elevations, and to compute flood elevations that are not given on the FIRM.
Q: Who can prepare an Elevation Certificate?
A: Elevation Certificates must be prepared and certified by a land surveyor, engineer or architect who is authorized by state or local law to certify elevation information. The Flood Control District may also sign the certificate.
Q: Why did I receive a Letter of Map Revision and not a Physical Map Revision?
A: A Letter of Map Revision (LOMR) is a much quicker revision than a Physical Map Revision (PMR). PMRs can take up to two years to become effective. In addition, a LOMR is a more cost-effective means for FEMA to revise a Flood Insurance Rate Map (FIRM). Due to budget constraints, FEMA uses the LOMR process as much as possible. You should keep a copy of the LOMR with your valuable papers. It will be important to have when you are ready to sell your property.
Q: Why wasn't my Letter of Map Change incorporated into the panel revision?
A: When a new National Flood Insurance Program map becomes effective it supersedes all Letters of Map Change (LOMCs) that have been issued for the affected map panel. When the changes reflected in the LOMC can be shown on the new FIRM, they are incorporated; however, some LOMC changes cannot be shown on the new FIRM because the change is too small to see on the map.
FEMA is in the process of developing procedures to automatically revalidate the LOMCs that were not incorporated.
Q: Will flood insurance rates be reduced when a flood control project is partially completed?
A: The answer to this question depends on whether the flood control project provides an adequate level of protection and if it involves federal funding. If the project is federally funded, then FEMA will revise the FIRM to show changes in the floodplain if the critical features of the project are under construction, 50 percent of the total cost has been expended, and 100 percent of the funding is authorized. When the FIRM is revised, the protected area will be designated Zone A99, and the flood insurance rate will be the same as in Zones B, C and X.
If a flood control project does not involve federal funds, FEMA would handle a map revision request as a Conditional Letter of Map Revision. The project sponsor must submit engineering and technical information to document the level of protection, how the floodplain is modified, the structural adequacy of the project, and operations and maintenance requirements. The FIRM would be changed after the project is complete and "as-built" plans have been certified and submitted to FEMA. At that time, the flood insurance rate in areas certified as protected would be the same as in Zones B, C and X.
Q: What is required to certify a levee as providing protection from the base flood?
A: In order for FEMA to recognize a levee system as providing protection from the base 100-year (one percent annual chance) flood, it must meet, and continue to meet minimum design, operation and maintenance standards established in Section 65.10 of the NFIP Regulations. The design criteria include, but may not be limited to, requirements for freeboard, closure devices, embankment protection, embankment and foundation stability, settlement and interior drainage. Public agencies must have complete operation and maintenance plans. The operation plan for the levee may include, but is not limited to, procedures for closures, interior drainage systems and emergency measures. The maintenance plan should detail responsibility and frequency of maintenance necessary to ensure the integrity of the levee system. All items necessary for a levee system to be recognized as providing protection from the one percent annual chance flood must be certified by a registered professional engineer. The certification requirement is different if a federal agency has responsibility for the levee.
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