(c) Overfill ratio is less than 2.88. It is expected that project 

 demands will be met with less than 2.88 cubic yards of borrow 

 for each cubic yard of fill needed. 



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As indicated previously, this procedure involves the procurement of 

 core borings in the borrow area and samples from the beach and nearshore 

 zones, and size analyses of all borings and samples. Readily available 

 sources of borrow material have frequently been in bays and lagoons where 

 the material is finer than the native beach material. In such cases, a 

 required volume of borrow material several times the needed in-place 

 volume on the beach would not be uncommon. Because of less availability 

 of bay and lagoon material, and ecological considerations in its use, 

 future planning is looking toward the use of offshore sources of fill 

 material. Since the source of borrow material will control the cost of 

 a beach fill to a major degree, evaluation of the required volume of 

 material from available areas is an important factor in economic design. 

 Ecological considerations in the borrow area are also important. 



5o333 Berm Elevation and Width . Beach berms are formed by the deposit 

 of material by wave action. The height of a berm is related to the cyclic 

 change in water level, normal foreshore and nearshore slopes, and the wave 

 regime. Some beaches have no berms; others have one or several. Figure 

 A-1 of Appendix A illustrates a beach zone with two berms. The lower berm, 

 the natural or normal berm, is formed by the uprush of normal wave action 

 during the ordinary range of water-level fluctuations. The higher berm, 

 or storm berm, is formed by wave action during storm conditions. During 

 most storms the water level will be higher than normal on the beach. 

 Wave overtopping may completely obliterate the normal beach berm, if over- 

 topping lasts long enough. The degree of protection to the backshore 

 depends greatly on the effectiveness of the storm berm. Beach berms must 

 be given careful consideration in the planning of a beach fill. If a beach 

 fill is placed to a height lower than the natural berm crest, a ridge will 

 form along the crest, and high water and high waves may overtop the berm 

 crest causing ponding and temporary flooding of the backshore. Such flood- 

 ing, if undesirable, may be avoided by filling the berm to a height slightly 

 above the natural berm crest. Several alternative techniques may be em- 

 ployed to estimate the height of the berm for design purposes. (See 

 Section 7.2 WAVE RUNUP, OVERTOPPING AND TRANSMISSION.) If a beach exists 

 at the site, the natural berm crest height can be measured, and an estimate 

 of future berm elevations can be made. An estimate also may be made by 

 comparison with other sites with similar exposure characteristics (waves 

 and tides) and beach material. If enough wave data (either developed from 

 synoptic surface weather charts or actual records) are available and appli- 

 cable to the project site, these data may be applied to the relationships 

 of wave runup, given by Savage (1959) which are discussed in Section 7.2, 

 to establish an estimated design berm crest height. 



Criteria for specifying berm width depend upon several factors. If 

 the purpose of the fill is to restore an eroded beach to protect backshore 



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