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4 LEVEE INSPECTION AND EVALUATION CONSIDERATIONS AND RELATIONSHIP TO DESIGN CRITERIA In order to confirm that a given proposed or existing levee satisfies the requirements for level of protection and structural integrity and should be recognized by the NFIP, FEMA must verify that its criteria have been met. Such a verification process can contribute to reducing the probability of levee failure. However, the committee recognizes that no levee evaluation procedure can be developed that assures that a given levee, new or old, will not fail at less than the stated level of protection. This chapter recommends procedures for reviewing designs, inspecting and evaluating the construction of new levees, and evaluating the effectiveness of existing levees. In developing its recommendations concerning the initial levee inspection and evaluation the committee took the position that such evaluations should be (1) technically adequate, (2) made with a cost conscious perspective, and (3) administratively and politically realistic. Concerning the first point, the committee does not believe it necessary or desirable for FEMA to develop an engineering organization for assessing technical adequacy. There are adequate professional capabilities within the private sector, civil engineering-oriented agencies of the federal government, and the governments of many states. Concerning the second point, the committee realizes that since many existing levees were built without the application of much, if any, engineering talent, the temptation may exist to exhaustively evaluate them. Although in some critical instances exhaustive subsurface evaluations may be necessary, the committee notes that such evaluations may be difficult to obtain if for no other reason than the high costs involved. In such instances primary reliance will necessarily be placed on prudent engineering judgement. Obviously, no set rule can be made; each site will present unique problems that must be addressed specifically. Several state-level water resources agencies already have programs for the inspection and evaluation of water resources structures. Where such programs apply also to levees and require procedures at least as restrictive as those recommended in this report, the committee proposes that the states' standards be given precedence. The interim FEMA policy (Appendix B) on existing levees requires map development contractors to determine that design standards have been met and that a field inspection or "suitable alternative" be performed to verify that levees appear structurally sound and adequately maintained. Certification from a federal or state agency or a professional engineer that these standards are met may be acceptable in lieu of an actual site-specific inspection by the -18-
contractor. The committee concurs in principle with this interim policy, but feels that more detailed guidance is required and that procedures for existing and new levees should differ markedly, particularly since the committee is recommending a lower credible design level for existing levees than is allowed under current policy. Development of a detailed inspection manual may be required. INSPECTION AND EVALUATION PROCEDURES FOR NEW LEVEES The evaluation of design and construction quality in conformance with the standards delineated in Chapter 3 requires the services of a professional engineer competent in hydrologic, hydraulic, structural, and geotechnical engineering and with specific experience in levee design. Designs must be prepared to meet or exceed NFIP standards. During construction, on-site inspections must confirm that the levee is built according to the approved plans and specifications. Since many levees with which this report is concerned exist or would be built along waterways where the federal government already has major responsibilities for levees, it would appear prudent for FEMA to investigate the possibility of using the expertise of the agencies involved to assure that FEMA's design evaluation and construction quality standards are met. Consideration should also be given to state involvement where water resources agencies are capable of undertaking the work. Should these options not be practical, it is appropriate for FEMA to use private engineering firms for evaluation of both design and construction conformance. The committee deliberated at great length on the question of engineer qualifications. The committee believes that no verification of qualifications is necessary should federal or state agencies accept the work. Where private sector firms are involved, however, the committee concluded that the best results could be obtained if first priority were given to the use of firms having experience in levee work. Although some local political entities responsible for levees have engineers on their staffs, the committee does not believe it generally desirable for those engineers to be responsible for the review of their own work. The committee recommends: ⢠In its administration of design evaluations and construction conformance inspections, FEMA should first pursue the possibility of using the services of federal agencies having water resources experience. Where federal participation can not be arranged, FEMA must use state agencies and private sector capabilities. INSPECTION AND EVALUATION PROCEDURES FOR EXISTING LEVEES Many existing federal and state levees have been built consistent with the recommended design and construction criteria. The agencies -19-
that designed and constructed those levees also periodically inspect the condition of the ones still under their control. In some instances, however, responsibility for the completed levees was assigned to local authorities for operation and maintenance; and there is much less assurance they have been acceptably maintained. Concerning levees that have been continuously maintained by the federal or state agency that designed and constructed them, the committee sees no need for independent evaluations. A statement from the agency concerned attesting to the adequacy of those levees should suffice. For levees that were built by federal or state forces and assigned to local entities for operation and maintenance, however, the committee believes independent evaluations are necessary as project conditions may have changed considerably since the assignment. Individuals needing information concerning levees may wish to check with state floodplain agencies. Those agencies may have data answering some of the evaluation questions. They must be checked before FEMA approves plans for a levee to ensure that any state requirements more restrictive than FEMA's have been met. The committee recommends: ⢠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. ⢠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. LECs could be selected from a list of firms that have submitted evidence that they are competent and capable of performing the required Work, according to appropriate contract selection rules. The number of LECs on hand would, of course, be determined by work load, but at least one would be available per FEMA (standard federal) region; contracts could change periodically. FEMA may want to establish an interagency LEC evaluation panel to facilitate the LEC selection process and to plan training for new LECs. The committee recommends: ⢠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. -20-
In most cases it will be to the applicant's financial benefit to have a levee recognized by FEMA. Therefore, the cost of the levee evaluation should be borne by the applicant and not by the general taxpayer through FEMA. This process is similar to NFIP procedures for changing flood insurance maps to reflect new data or the impacts of new flood control structures. In the case of existing levees, the Flood Insurance Study process may or may not have already given a levee credit as providing protection from the 100-year flood. The two cases need to be handled differently. Previously Unrecognized Levees The committee's recommendation that existing levees providing protection against a flood at or exceeding the 25-year level (plus freeboard) be credited for the purpose of reducing insurance rates departs from current FEMA policy. In these situations the beneficiaries have an economic incentive to have their levee recognized and should have the responsibility to initiate and pay for the inspection and evaluation, including the retention of engineering services. The committee recommends: ⢠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. The inspection and evaluation for existing levees is complicated by the fact that conditions within levees are concealed from view, the levees may have been in place for decades, and construction may have had many raising and repair stages. It is important that the original plans, as built drawings, boring logs, profiles, and records of operation and maintenance and past experiences in floods be reviewed. There are no substitute optical or visual means for looking beneath the earth surface into the interior or beneath the bottom of a levee. Test drilling and other new methods can sample subsurface conditions, but the percentage of area actually covered, at best, is generally far less than a fraction of 1 percent of the totals. Test drilling, sampling, and evaluation are valuable for investigating subsurface conditions and are important tools for evaluating existing conditions. Soil borings should be made sufficiently close together to provide a reasonable representation of subsurface conditions. Following completion of the inspection, the LEG (or other responsible entity) would submit a report to the applicant, who then would have the option of submitting the report to FEMA for zone designation and map amendments. All costs would be borne by the applicant. Once the completed report is submitted, FEMA would finance -21-
the review of the report and the costs of publishing and distributing a revised map. This procedure is essentially the same as the current map revision procedure. Previously Recognized Levees The committee recommends: ⢠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. Communities with levees credited with removing areas from the 100-year floodplain should have those levees restudied to ensure that the levees meet adopted hydrologic and engineering criteria. Because most levees (particularly those built by federal agencies to protect large urban areas) are expected to still prove adequate and because there are limited funds for restudies, a priority list should be developed. The following criteria should be used in setting priorities for communities to be restudied: 1. If the levee was designed, built, or maintained by a private organization. 2. If there has been significant tributary catchment urbanization, floodplain encroachment, or other development that would increase flood heights along the levee since the original study. 3. If the levee protects a large population or critical facilities. The committee recommends: ⢠FEMA should develop a short and simple checklist that can be used to make a quick assessment of whether a levee meets recommended criteria. Such a checklist would be used by a flood insurance restudy contractor paid by FEMA to make a quick check of each levee's condition. The checklist should cover slope, maintenance, and top elevation (to determine settling). It would not include subsurface exploration or other time consuming investigations. The restudy contractor would separate those communities with levees that appear to be clearly in good shape from those in bad or doubtful shape. When the restudy contractor finds a levee in doubtful or bad shape, he will inform FEMA who will notify the community that the levee cannot be considered adequate for protecting against the 100-year flood. The community may either contract and pay for a thorough -22-
evaluation, as described in the previous section, or accept the fact that the levee will no longer be recognized by FEMA. If the community cannot show that the levee is still adequate, the area behind it will be mapped as 100-year floodplain (A1-A30 Zone). This expedites review of previously recognized levees. Levees requiring the greatest and earliest attention should be studied first, and FEMA would finance the preliminary studies to determine if an earlier FEMA decision should be changed. The community would not be required to pay for this preliminary study unless an on-site check gave FEMA reasonable belief that the levee should no longer be considered adequate. Community officials would, of course, be given the usual opportunities for review, consultation, and appeal of the restudy conclusions. OPERATION AND MAINTENANCE EVALUATION The evaluator should review the current operation and maintenance plan and actual activity in the context of the operation and maintenance needs of the levee. Criteria for operation and maintenance should be consistent with those (see Chapter 5) required of levee owners for continued levee recognition. The same evaluator certifying the levee's design and construction would ordinarily also evaluate the operation and maintenance practices of the levee owner. FEMA should not recognize any levee unless it is properly operated and maintained. Failure to do so would be cause for redesignating the area behind the levee as not protected. -23-
