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A Levee Policy for the National Flood Insurance Program (1982)

Chapter: SUMMARY OF RECOMMENDATIONS

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Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
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Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
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Page 66
Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
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Page 67
Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
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Page 68
Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
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Page 69
Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
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Page 70
Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
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Page 71
Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
×
Page 72
Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
×
Page 73
Suggested Citation:"SUMMARY OF RECOMMENDATIONS." National Research Council. 1982. A Levee Policy for the National Flood Insurance Program. Washington, DC: The National Academies Press. doi: 10.17226/19600.
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Page 74

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10 SUMMARY OF RECOMMENDATIONS Engineering Criteria for Levee Recognition In order to encourage communities to continue the operation and maintenance of existing levees that have been soundly engineered and are adequately maintained and in recognition of the fact that such levees do reduce actuarial flood risk, FEMA can legitimately recognize structurally sound levees that contain at least the 25-year flood for purposes of adjusting flood insurance rates. Specifically: • Existing levees should be recognized for the purpose of reducing insurance rates where they provide protection against 25-year or larger floods and where they meet specified structural design criteria, including requisite freeboard. However, since the basic objective of the NFIP is to mitigate flood damages and the basic program prohibits construction below the 100-year level, FEMA should require construction of new levees to the 100-year level. Further, the additional cost required to build a levee to contain the 100-year flood can often be justified at the time of initial levee construction. Therefore: • New levees should be recognized for the purpose of reducing insurance rates where they provide protection against 100-year or larger floods and where they meet specified structural design criteria including freeboard. All levees on which construction begins after a date to be determined by FEMA should be considered new levees. With respect to structural safety, the same criteria shall be used for both existing and proposed levees in determining eligibility for recognition by the NFIP. Therefore: • All levees (existing and new) to be given credit for reducing flood risk in the NFIP must meet standard minimum engineering -65-

criteria with respect to geometric parameters, freeboard, soils and foundations, interior drainage, closure devices, and rights of way. Flood stages that change over time due to any of a variety of factors (e.g., increased urbanization, removal of natural valley storage, construction of reservoirs in upper reaches of large river systems) influence the hydrologic risk at a specific site. Therefore; • FEMA should monitor watershed and channel changes where hydrologic risk is increasing and respond to significant changes with restudies and subsequent map and rate revisions. Levee Inspection and Evaluation Each levee must be individually evaluated, hydrologically and structurally, before acceptance into the NFIP. There is ample engineering expertise in federal and state water resources agencies and in engineering firms in the private sector to conduct design evaluations and construction conformance inspections. Since many urban levees exist or would be built along waterways where the federal government already has major levee responsibilities, it would appear prudent that: • In its administration of design evaluations and construction conformance inspections, FEMA should first pursue the possibility of using the services of federal and state agencies having water resources experience. Where federal participation can not be arranged, FEMA must use state and private sector capabilities. In order to reduce the workload for levee inspection: • Where responsible federal or state agencies have had continuous maintenance responsibilities on levees they designed and constructed, and will attest to their adequacy under FEMA standards, independent evaluations should not usually be required. Evaluations should be required, however, on levees that were designed and constructed by federal agencies but are currently being operated and maintained by others. In some cases, neither a federal nor a state agency will be willing to undertake levee evaluation: -66-

• Where a federal or state agency does not evaluate a levee, levee evaluations should be done by "levee evaluation contractors" (LECs), private consulting firms designated by FEMA. Since it will be to an applicant's financial benefit to have an existing levee at or exceeding the 25-year level (plus freeboard) recognized by FEMA for the purpose of reducing insurance rates it follows that: • While FEMA should designate qualified private consulting firms to be LECs, the firms should work under contract to an applicant interested in having a levee evaluated for recognition by FEMA. All costs of the LECs' work should be borne by the applicant. Further: • Since recognition of 25-year levees for the purpose of reducing insurance rates would represent an important change in federal policy, FEMA should publicize the benefits, costs, and procedural details for levee recognition. Communities may have had levees already credited with removing property from the 100-year floodplain even though those levees do not meet sound structural or maintenance standards or may no longer protect against the 100-year flood. It is, therefore, concluded that; • FEMA should inventory all levees previously credited as providing protection from the 100-year flood, set priorities, and schedule communities for restudy to reevaluate the levees. Since most previously credited levees are expected to prove adequate and since restudy funds should not be expended needlessly: • FEMA should develop a short and simple checklist that can be used to make a quick assessment of whether a levee meets recommended criteria. Requirements of Levee Owners Human operated closures such as street gates are legitimate parts of planned levee systems, but general human intervention (sand bagging, emergency earth fill, etc.) for the purpose of increasing a -67-

levee's design level of protection during an imminent flood situation does not provide reliable protection. Consequently: • FEMA should confirm its interim policy that does not recognize sand bags on top of levees and other types of human intervention, except for structural closures which are legitimate parts of planned levee systems, as augmenting a levee system's design level of protection. The Corps of Engineers has a good record on levee operation and maintenance following procedures contained in Federal Code 208.10, Title 33. FEMA can use this code as a basis for developing its procedures: • Federal Code 208.10, Title 33, "Local flood protection works; maintenance and operation of facilities," should be modified where not well suited, supplemented for interior drainage, and adopted by FEMA as a guideline for operation and maintenance of levee systems. While this code can provide general guidelines, each local situation is different. Consequently: • A specific operation and maintenance plan, tailored to the local needs, must be formally adopted by the levee owner for a levee to be credited and continue to be credited in the NFIP. Only regular maintenance programs are effective. Consequently: • The operation and maintenance plan must provide for periodic inspections. The plan should be completed within a designated time period, meet the requirements of, and be acceptable to FEMA. Each inspection must be by a professional engineer retained by the levee owner and registered in the state in which the levee is located. A written report to the levee owner should be promptly prepared and certified by the professional engineer making the inspection. The report must specifically describe items found deficient and emerging potential future problem areas. Copies of the certified report should be sent by the certifying professional engineer to the regional FEMA office. Also, a copy should be provided the local political entities which have responsibilities to FEMA for the levee-protected area. FEMA should follow up to assure corrections -68-

are made within a reasonable length of time. In instances where corrections are not made to critical deficiencies, FEMA should withdraw recognition. Requirements of Local Communities Levee recognition has many dimensions, each with its own requirements of local communities. For consistency with the policy of not permitting construction of unprotected new structures in the 100-year floodplain: • FEMA should require the elevation of new residential structures and the flood-proofing of other new buildings in all areas protected by levees unable to contain the 100-year flood. In recognition of the degree of residual risk behind levees providing less than 500-year flood protection: • FEMA should require purchase of flood insurance in all areas where the ground is lower than the unconfined 100-year flood level except where protected by a levee built to contain the 500-year flood. Critical facilities, such as hospitals and natural gas terminals, whose flooding or discontinuity of service would create untoward hardship or damage for the community as a whole should not be permitted in the floodplain where alternative sites are available nearby. Consequently: •' Communities should regulate the placement of critical facilities (not regulated by some higher level of government) in all leveed areas in accordance with the procedures of Executive Order 11988. To minimize floodplain development by individuals unaware of the hazard: • Owners, tenants, and lenders occupying areas designated as protected by levees should be notified periodically by responsible local officials that their land in the levee-protected area is still subject to flooding in the event of levee failure. The damages, should levee failure occur, can be considerably reduced by warning people behind levees, identifying evacuation routes -69-

and police procedures for expediting evacuation, advising of appropriate temporary shelter and food for evacuees, and assuring that law and order are maintained in the flooded area. Therefore: • Local officials of any NFIP participating community protected by a levee, regardless of its size and reliability, should prepare and promulgate an action plan for warning and evacuation in the event of levee failure. Liability of Local Governments and Levee Districts Concerning Levee Maintenance and Floodplain Management Since courts do not hold the federal government liable for levee failures but are displaying greater sympathy for the plight of land owners subjected to increased flooding due to municipal negligence, it is necessary that: • FEMA should help make local governments and special districts aware of the possibility of liability for actions or nonactions that aggravate flood hazards. • FEMA should, in appropriate cases, seek to recoup federal flood-related costs (including flood insurance payments, disaster assistance, etc.) from levee owners/operators when such costs arise from improper operation and maintenance of levee and associated interior drainage facilities. Treatment of Levees in the Insurance Aspects of the NFIP Policyholders for property behind levees should pay premiums determined by reasonable estimates of the residual flood damages. Therefore: • Regardless of the level of protection provided, the levee-protected area should be disaggregated into flood risk zones and an actuarial rate be established for each zone that reflects the degree of protection actually provided by the levees. Insurance rate structures should encourage damage mitigating measures by recognizing well-engineered and maintained levees. Conversely, rate increases should follow levee owner failure to fulfill obligations. Therefore: -70-

• Consistent with the design levels of protection recommended in Chapter 3, NFIP policyholders in areas behind existing levees that offer more than 25-year protection or new levees affording 100-year protection or greater should pay lower rates that reflect the reduced risk of property damage. The adjustment procedure needs to be kept reasonably simple within the limits set by past practice. Specifically: • The levee flood risk zones should match the existing flood risk zones established for the regular Flood Insurance Programs. As part of a long-run goal of promoting program equity: • FEMA should continue its efforts to establish an actuarial rate basis for the Flood Insurance Program and, as far as practical, convert its present rate schedule to actuarial rates. The actuarial rates, as is done by the private insurance industry, would be updated annually to reflect experience, claims paid, and the cost of doing business. In order to facilitate levee rating according to physical condition: • FEMA should contract for the development of a list of key categories concerning the physical condition of a levee that would be used to evaluate the levee's ability to function effectively and concerning use of those factors to estimate geotechnical risk. An unsatisfactory rating would result in increased flood insurance premiums. Floodplain Mapping Approaches in Levee-Protected Areas A Flood Hazard Boundary Map (FHBM) is prepared by FEMA for community use on an interim basis until better mapping is developed. While revisions to the emergency program and published FHBMs are not desirable: • All levees, dikes, or floodwalls should be labeled as such on any new or revised FHBM. Also, the areas protected by levees providing 100-year or greater protection should be delineated on the new or revised FHBMs as Zone LP. Areas protected by levees not meeting -71-

this standard would continue to be mapped as Zone A. The situation is different for the Flood Insurance Rate Maps (FIRMs) used by communities in the regular program: • The location of all levees, dikes, or floodwalls credited as providing 100-year protection or more should be clearly denoted on all future FIRMs. Implementing insurance purchase requirements in levee protected areas, the levee-protected areas must be so designated on the FIRM and the information necessary to determine insurance rates must be provided. Therefore: • Areas behind recognized 100-year levees that would be flooded (assuming no levee) by a 100-year flood should be designated as Zone ALP. Areas between the 100-year flood boundary and 500-year flood boundary should be designated as Zone BLP. To facilitate floodplain management activities: • The locations of all credited levees, dikes, and floodwalls should be clearly denoted on all Floodway Maps. • Areas behind credited levees providing 100-year protection that would be flooded during a 500-year flood should be shown on Floodway Maps. If a levee with a level of protection of less than 100 years is to be recognized for flood insurance purposes, the FIRM must carry a designation that will allow appropriate rates to be determined for protected properties. On FIRMs: • FEMA should create an AL(No.) Zone that would designate an area protected by a levee with a frequency of protection defined by the (No.). For example, if the levee had an elevation equal to the 40-year flood (plus required freeboard), then the Zone would be AL(40). Since several FEMA maps may be required to show a complete evacuation route and the showing of route portions is not particularly helpful: • FEMA should not make it a mandatory requirement to include evacuation routes on -72-

maps. If the information is available when the maps are being prepared and if it makes sense from a community-to-community mapping standpoint, then the evacuation routes could be included on the maps. In other cases, it may be expeditious for communities to develop their own special evacuation route maps. Greater attention should be placed on linking levee operation and interior drainage problems. Therefore: • Interior drainage situations in areas on the landside of levees should be analyzed in conjunction with the riverine flood analysis, and the areas flooded by interior drainage should be shown on FEMA maps in accordance with current practice. Appropriate consideration should be given to correlation of the event on the river and the event causing the interior drainage problem. -73-

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