This project was the first in the United States in which an unprotec- 

 ted hydraulic pipeline dredge was operated successfully in the open sea. 

 Although highly successful in this project, this procedure has a critical 

 limitation — the necessity for a nearby harbor. Experience gained on this 

 project and the hopper-dredge operation at Sea Girt, (Section 6.322) pro- 

 vides the techniques for further recovery of valuable beach sand from off- 

 shore sources. 



6.4 SAND DUNES 



Foredunes (Fig. 6-28) form just behind the beach and perform an im- 

 portant role in littoral processes. (See Sections 5.4 and 4.6.) Fore- 

 dunes function as a reservoir of sand to nourish eroding beaches during 

 high water, and as a levee to prevent waves from damaging backshore areas. 

 As such, they are valuable nonrigid shore protection structures. Fore- 

 dunes are created naturally by the combined action of sand, wind, and 

 biota. Behind sandy beaches, foredunes often form a continuous line to 

 resist overtopping by high water and wave action. 



Figure 6-28. Foredune System 



6o41 SAND MOVe-lENT 



Winds with sufficient velocity to move sand particles deflate the 

 exposed beach, and transport sand in three ways: 



6-36 



