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lv_section6510_0408347 Federal Emergency Management Agency, DHS §65.10 occurred in the flood plain since the ex- isting floodway was developed. If the original hydraulic computer model is not available, an alternate hydraulic computer model may be used provided the alternate model has been cali- brated so as to reproduce the original water surface profile of the original hy- draulic computer model. The alternate model must be then modified to in- clude all encroachments that have oc- curred since the existing floodway was developed. (ii) The floodway analysis must be performed with the modified computer model using the desired floodway lim- its. (iii) The floodway limits must be set so that combined effects of the past en- croachments and the new floodway limits do not increase the effective base flood elevations by more than the amount specified in §60.3(d)(2). Copies of the input and output data from the original and modified computer models must be submitted. (3) Delineation of the revised floodway on a copy of the effective NFIP map and a suitable topographic map. (d) Certification requirements. All anal- yses submitted shall be certified by a registered professional engineer. All topographic data shall be certified by a registered professional engineer or li- censed land surveyor. Certifications are subject to the definition given at §65.2 of this subchapter. (e) Submission procedures. All requests that involve changes to floodways shall be submitted to the appropriate FEMA Regional Office servicing the commu- nity’s geographic area. [51 FR 30315, Aug. 25, 1986] §65.8 Review of proposed projects. A community, or an individual through the community, may request FEMA’s comments on whether a pro- posed project, if built as proposed, would justify a map revision. FEMA’s comments will be issued in the form of a letter, termed a Conditional Letter of Map Revision, in accordance with 44 CFR part 72. The data required to sup- port such requests are the same as those required for final revisions under §§65.5, 65.6, and 65.7, except as-built cer- tification is not required. All such re- quests shall be submitted to the FEMA Headquarters Office in Washington, DC, and shall be accompanied by the appropriate payment, in accordance with 44 CFR part 72. [62 FR 5736, Feb. 6, 1997] §65.9 Review and response by the Ad- ministrator. If any questions or problems arise during review, FEMA will consult the Chief Executive Officer of the commu- nity (CEO), the community official des- ignated by the CEO, and/or the re- quester for resolution. Upon receipt of a revision request, the Administrator shall mail an acknowledgment of re- ceipt of such request to the CEO. With- in 90 days of receiving the request with all necessary information, the Admin- istrator shall notify the CEO of one or more of the following: (a) The effective map(s) shall not be modified; (b) The base flood elevations on the effective FIRM shall be modified and new base flood elevations shall be es- tablished under the provisions of part 67 of this subchapter; (c) The changes requested are ap- proved and the map(s) amended by Let- ter of Map Revision (LOMR); (d) The changes requested are ap- proved and a revised map(s) will be printed and distributed; (e) The changes requested are not of such a significant nature as to warrant a reissuance or revision of the flood in- surance study or maps and will be de- ferred until such time as a significant change occurs; (f) An additional 90 days is required to evaluate the scientific or technical data submitted; or (g) Additional data are required to support the revision request. (h) The required payment has not been submitted in accordance with 44 CFR part 72, no review will be con- ducted and no determination will be issued until payment is received. [51 FR 30315, Aug. 25, 1986; 61 FR 46331, Aug. 30, 1996, as amended at 62 FR 5736, Feb. 6, 1997] §65.10 Mapping of areas protected by levee systems. (a) General. For purposes of the NFIP, FEMA will only recognize in its flood VerDate Aug<31>2005 00:53 Oct 24, 2006 Jkt 208182 PO 00000 Frm 00357 Fmt 8010 Sfmt 8010 Y:\SGML\208182.XXX 208182ccoleman on PROD1PC71 with CFR 348 44 CFR Ch. I (10–1–06 Edition) §65.10 hazard and risk mapping effort those levee systems that meet, and continue to meet, minimum design, operation, and maintenance standards that are consistent with the level of protection sought through the comprehensive flood plain management criteria estab- lished by §60.3 of this subchapter. Ac- cordingly, this section describes the types of information FEMA needs to recognize, on NFIP maps, that a levee system provides protection from the base flood. This information must be supplied to FEMA by the community or other party seeking recognition of such a levee system at the time a flood risk study or restudy is conducted, when a map revision under the provi- sions of part 65 of this subchapter is sought based on a levee system, and upon request by the Administrator dur- ing the review of previously recognized structures. The FEMA review will be for the sole purpose of establishing ap- propriate risk zone determinations for NFIP maps and shall not constitute a determination by FEMA as to how a structure or system will perform in a flood event. (b) Design criteria. For levees to be recognized by FEMA, evidence that adequate design and operation and maintenance systems are in place to provide reasonable assurance that pro- tection from the base flood exists must be provided. The following require- ments must be met: (1) Freeboard. (i) Riverine levees must provide a minimum freeboard of three feet above the water-surface level of the base flood. An additional one foot above the minimum is required within 100 feet in either side of structures (such as bridges) riverward of the levee or wherever the flow is constricted. An additional one-half foot above the min- imum at the upstream end of the levee, tapering to not less than the minimum at the downstream end of the levee, is also required. (ii) Occasionally, exceptions to the minimum riverine freeboard require- ment described in paragraph (b)(1)(i) of this section, may be approved. Appro- priate engineering analyses dem- onstrating adequate protection with a lesser freeboard must be submitted to support a request for such an excep- tion. The material presented must evaluate the uncertainty in the esti- mated base flood elevation profile and include, but not necessarily be limited to an assessment of statistical con- fidence limits of the 100-year discharge; changes in stage-discharge relation- ships; and the sources, potential, and magnitude of debris, sediment, and ice accumulation. It must be also shown that the levee will remain structurally stable during the base flood when such additional loading considerations are imposed. Under no circumstances will freeboard of less than two feet be ac- cepted. (iii) For coastal levees, the freeboard must be established at one foot above the height of the one percent wave or the maximum wave runup (whichever is greater) associated with the 100-year stillwater surge elevation at the site. (iv) Occasionally, exceptions to the minimum coastal levee freeboard re- quirement described in paragraph (b)(1)(iii) of this section, may be ap- proved. Appropriate engineering anal- yses demonstrating adequate protec- tion with a lesser freeboard must be submitted to support a request for such an exception. The material presented must evaluate the uncertainty in the estimated base flood loading condi- tions. Particular emphasis must be placed on the effects of wave attack and overtopping on the stability of the levee. Under no circumstances, how- ever, will a freeboard of less than two feet above the 100-year stillwater surge elevation be accepted. (2) Closures. All openings must be pro- vided with closure devices that are structural parts of the system during operation and design according to sound engineering practice. (3) Embankment protection. Engineer- ing analyses must be submitted that demonstrate that no appreciable ero- sion of the levee embankment can be expected during the base flood, as a re- sult of either currents or waves, and that anticipated erosion will not result in failure of the levee embankment or foundation directly or indirectly through reduction of the seepage path and subsequent instability. The factors to be addressed in such analyses in- clude, but are not limited to: Expected flow velocities (especially in con- stricted areas); expected wind and wave VerDate Aug<31>2005 00:53 Oct 24, 2006 Jkt 208182 PO 00000 Frm 00358 Fmt 8010 Sfmt 8010 Y:\SGML\208182.XXX 208182ccoleman on PROD1PC71 with CFR 349 Federal Emergency Management Agency, DHS §65.10 action; ice loading; impact of debris; slope protection techniques; duration of flooding at various stages and ve- locities; embankment and foundation materials; levee alignment, bends, and transitions; and levee side slopes. (4) Embankment and foundation sta- bility. Engineering analyses that evalu- ate levee embankment stability must be submitted. The analyses provided shall evaluate expected seepage during loading conditions associated with the base flood and shall demonstrate that seepage into or through the levee foun- dation and embankment will not jeop- ardize embankment or foundation sta- bility. An alternative analysis dem- onstrating that the levee is designed and constructed for stability against loading conditions for Case IV as de- fined in the U.S. Army Corps of Engi- neers (COE) manual, ‘‘Design and Con- struction of Levees’’ (EM 1110–2–1913, Chapter 6, Section II), may be used. The factors that shall be addressed in the analyses include: Depth of flooding, duration of flooding, embankment ge- ometry and length of seepage path at critical locations, embankment and foundation materials, embankment compaction, penetrations, other design factors affecting seepage (such as drainage layers), and other design fac- tors affecting embankment and founda- tion stability (such as berms). (5) Settlement. Engineering analyses must be submitted that assess the po- tential and magnitude of future losses of freeboard as a result of levee settle- ment and demonstrate that freeboard will be maintained within the min- imum standards set forth in paragraph (b)(1) of this section. This analysis must address embankment loads, com- pressibility of embankment soils, com- pressibility of foundation soils, age of the levee system, and construction compaction methods. In addition, de- tailed settlement analysis using proce- dures such as those described in the COE manual, ‘‘Soil Mechanics Design— Settlement Analysis’’ (EM 1100–2–1904) must be submitted. (6) Interior drainage. An analysis must be submitted that identifies the source(s) of such flooding, the extent of the flooded area, and, if the average depth is greater than one foot, the water-surface elevation(s) of the base flood. This analysis must be based on the joint probability of interior and ex- terior flooding and the capacity of fa- cilities (such as drainage lines and pumps) for evacuating interior flood- waters. (7) Other design criteria. In unique sit- uations, such as those where the levee system has relatively high vulner- ability, FEMA may require that other design criteria and analyses be sub- mitted to show that the levees provide adequate protection. In such situa- tions, sound engineering practice will be the standard on which FEMA will base its determinations. FEMA will also provide the rationale for requiring this additional information. (c) Operation plans and criteria. For a levee system to be recognized, the operational criteria must be as de- scribed below. All closure devices or mechanical systems for internal drain- age, whether manual or automatic, must be operated in accordance with an officially adopted operation manual, a copy of which must be provided to FEMA by the operator when levee or drainage system recognition is being sought or when the manual for a pre- viously recognized system is revised in any manner. All operations must be under the jurisdiction of a Federal or State agency, an agency created by Federal or State law, or an agency of a community participating in the NFIP. (1) Closures. Operation plans for clo- sures must include the following: (i) Documentation of the flood warn- ing system, under the jurisdiction of Federal, State, or community officials, that will be used to trigger emergency operation activities and demonstration that sufficient flood warning time ex- ists for the completed operation of all closure structures, including necessary sealing, before floodwaters reach the base of the closure. (ii) A formal plan of operation in- cluding specific actions and assign- ments of responsibility by individual name or title. (iii) Provisions for periodic oper- ation, at not less than one-year inter- vals, of the closure structure for test- ing and training purposes. (2) Interior drainage systems. Interior drainage systems associated with levee systems usually include storage areas, VerDate Aug<31>2005 00:53 Oct 24, 2006 Jkt 208182 PO 00000 Frm 00359 Fmt 8010 Sfmt 8010 Y:\SGML\208182.XXX 208182ccoleman on PROD1PC71 with CFR 350 44 CFR Ch. I (10–1–06 Edition) §65.11 gravity outlets, pumping stations, or a combination thereof. These drainage systems will be recognized by FEMA on NFIP maps for flood protection pur- poses only if the following minimum criteria are included in the operation plan: (i) Documentation of the flood warn- ing system, under the jurisdiction of Federal, State, or community officials, that will be used to trigger emergency operation activities and demonstration that sufficient flood warning time ex- ists to permit activation of mechanized portions of the drainage system. (ii) A formal plan of operation in- cluding specific actions and assign- ments of responsibility by individual name or title. (iii) Provision for manual backup for the activation of automatic systems. (iv) Provisions for periodic inspection of interior drainage systems and peri- odic operation of any mechanized por- tions for testing and training purposes. No more than one year shall elapse be- tween either the inspections or the op- erations. (3) Other operation plans and criteria. Other operating plans and criteria may be required by FEMA to ensure that adequate protection is provided in spe- cific situations. In such cases, sound emergency management practice will be the standard upon which FEMA de- terminations will be based. (d) Maintenance plans and criteria. For levee systems to be recognized as pro- viding protection from the base flood, the maintenance criteria must be as described herein. Levee systems must be maintained in accordance with an officially adopted maintenance plan, and a copy of this plan must be pro- vided to FEMA by the owner of the levee system when recognition is being sought or when the plan for a pre- viously recognized system is revised in any manner. All maintenance activi- ties must be under the jurisdiction of a Federal or State agency, an agency created by Federal or State law, or an agency of a community participating in the NFIP that must assume ulti- mate responsibility for maintenance. This plan must document the formal procedure that ensures that the sta- bility, height, and overall integrity of the levee and its associated structures and systems are maintained. At a min- imum, maintenance plans shall specify the maintenance activities to be per- formed, the frequency of their perform- ance, and the person by name or title responsible for their performance. (e) Certification requirements. Data submitted to support that a given levee system complies with the structural requirements set forth in paragraphs (b)(1) through (7) of this section must be certified by a registered professional engineer. Also, certified as-built plans of the levee must be submitted. Certifi- cations are subject to the definition given at §65.2 of this subchapter. In lieu of these structural requirements, a Federal agency with responsibility for levee design may certify that the levee has been adequately designed and con- structed to provide protection against the base flood. [51 FR 30316, Aug. 25, 1986] §65.11 Evaluation of sand dunes in mapping coastal flood hazard areas. (a) General conditions. For purposes of the NFIP, FEMA will consider storm- induced dune erosion potential in its determination of coastal flood hazards and risk mapping efforts. The criterion to be used in the evaluation of dune erosion will apply to primary frontal dunes as defined in §59.1, but does not apply to artificially designed and con- structed dunes that are not well-estab- lished with long-standing vegetative cover, such as the placement of sand materials in a dune-like formation. (b) Evaluation criterion. Primary fron- tal dunes will not be considered as ef- fective barriers to base flood storm surges and associated wave action where the cross-sectional area of the primary frontal dune, as measured per- pendicular to the shoreline and above the 100-year stillwater flood elevation and seaward of the dune crest, is equal to, or less than, 540 square feet. (c) Exceptions. Exceptions to the eval- uation criterion may be granted where it can be demonstrated through au- thoritative historical documentation that the primary frontal dunes at a specific site withstood previous base flood storm surges and associated wave action. [53 FR 16279, May 6, 1988] VerDate Aug<31>2005 00:53 Oct 24, 2006 Jkt 208182 PO 00000 Frm 00360 Fmt 8010 Sfmt 8010 Y:\SGML\208182.XXX 208182ccoleman on PROD1PC71 with CFR