PART VII: DESIGN AND SEQUENCE OF EXPLORATION PROGRAMS 



119. The design of a borrow source exploration program involves a 

 determination of the scope of the program in terms of the extent of the area 

 to be surveyed and the location and amount of geophysical and core data needed 

 to adequately cover the exploration area. In addition, the planning process 

 includes establishing the requirements for various phases of the operation 

 including time, equipment, and personnel requirements that can be used to 

 estimate costs. Flexibility is a key element of program design. Need for 

 changes and adjustments of the basic plan should be expected as incoming field 

 data provides more accurate and detailed information on the exploration area. 



Defining Boundaries 



120. Delineating the boundaries of the area to be explored is an impor- 

 tant aspect of the planning process. Two types of boundaries may be deline- 

 ated: (a) the overall outer boundaries of the general exploration area; and 

 (b) boundaries of subareas within general limits where various factors pre- 

 clude either the occurrence of suitable borrow material or recovering any 

 material that may exist. The maximum limits of the general exploration area, 

 if not otherwise restricted, are set by the economically feasible transport 

 distance between the project beach and potential borrow sources. Other impor- 

 tant factors that may limit the outer boundaries or create restricted subareas 

 are bathymetry, navigation hazards, special-use areas, adverse geological con- 

 ditions, and environmental considerations. 



121. Restrictions due to bathymetry occur where water depths are too 

 shallow or too deep to allow operation of suitable equipment for dredging and 

 transporting fill material. The landward limit of the general exploration 

 area is usually based on bathymetry and, in places, the seaward limit as well. 

 Shallow shoal areas and hazardous obstructions occurring within general limits 

 may create inaccessible subareas that must be excluded from the exploration 

 plan. Special -use areas in which recovery and transport of fill material are 

 restricted or precluded include areas of heavy maritime traffic, waste dis- 

 posal sites, cable and pipeline routes, fish havens, offshore structures, and 

 localities reserved for military use. Unfavorable geological conditions usu- 

 ally occur in the form of areas of consolidated rock or glacial till and areas 



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