6.3 PROTECTIVE BEACHES 



6.31 GENERAL 



Planning analysis for a protective beach is described in Section 5.3. 

 Protective beaches may be built with land-hauled sand fill or by pumping 

 sand with a floating dredge through a pipeline to the beach. The dredge 

 picks up the material at the borrow area and pumps it directly to the fill 

 area. The direct pumping method is better suited where the borrow area is 

 not exposed to wave action, although a specially equipped dredge was used 

 successfully in an exposed location in Redondo Beach, Malaga Cove, Calif- 

 ornia. (See Section 6.323.) This dredge was held in position by cables 

 and anchors rather than spuds, and used a flexible suction line with jet 

 agitation rather than the conventional rigid ladder and cutterhead. 

 Dredges with a rigid ladder and cutterhead were used on beach fills at 

 Pompano Beach and Fort Pierce, Florida, where the borrow area was off- 

 shore and exposed to the open ocean. 



Some hopper dredges are now available with pump-out capability. 

 Hopper dredges load at the borrow site, (normally offshore), move close 

 to the fill site, and then pump from the hoppers through a submerged pipe- 

 line to the beach. (See Section 6.322.) 



The choice of method depends on the location of the borrow source and 

 availability of suitable equipment. Borrow sources in bays and lagoons 

 may become depleted, or lonexploitable because of injurious ecological 

 effects. It is now necessary to place increased reliance on offshore 

 sources. CERC is studying the geomorphology, sediments, and structure of 

 the Inner Continental Shelf with the primary purpose of finding sand 

 deposits suitable for beach fill. Results are published as they become 

 available. (Duane and Meisburger, 1969, Meisburger and Duane, 1971, 

 Meisburger, 1972.) Sand from offshore sources is frequently of better 

 quality for beach fill, because it contains less fine grain size materials. 

 However, equipment suitable for dredging and transporting sand to the beach 

 is not yet readily available. As equipment becomes available, offshore 

 borrow areas will become more important sources of beach fill material. 



6.32 EXISTING PROTECTIVE BEACHES 



Restoration and widening of beaches have come into increasing use in 

 recent years. Examples are Ocean City, New Jersey (Watts, 1956), Virginia 

 Beach, Virginia (Watts, 1959), (Wrightsville Beach and Carolina Beach, 

 North Carolina (Vallianos, 1970), and Harrison County, Mississippi 

 (Escoffier and Dolive, 1954 and Watts, 1958.) Figures 6-14 through 6-23 

 illustrate details of these projects with before-and-after photographs. 

 A test of beach widening and nourishment from an offshore source by hopper 

 dredge, in 1966, at Sea Girt, New Jersey is described in Section 6.322.' 

 In 1968, beach widening and nourishment from an offshore source was accom- 

 plished by a pipeline dredge at Redondo Beach, California. (See Section 

 6.323.) Of the projects mentioned, Carolina Beach, Sea Girt and Redondo 

 Beach are discussed. 



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