Economics, dredging

The bathymetry at and near the borrow area which may prevent the employment of economic dredging equipment or may require dredging of an access channel. 

Both aspects, and their impact on the economical and environmental cost of entrance chaimels construction and dredging maintenance, should be taken into accoimt in the entrance chaimel and breakwater design. The application of present methodology can help to find the optimum design. 

The possibilities and limitations of the dredging plant in combination with the boundary conditions may also affect the technical and economic feasibility of a project. For instance ... 

Technical and economic evaluations of the feasibility of a dredging project clearly require both a full inventory of the requirements of the Client (expressed as the desired properties of the fill mass) and the boundary conditions, and also a thorough knowledge of the characteristics of the available dredging plant and reclamation methods. 

The area required by plain suction dredgers is dictated by slope development of the borrow area as a result of the dredging process. Economics usually restrict the volume which can be extracted from a borrow pit by a plain suction dredger to approximately 2/3 of the geometrical available volume. 

For stationary dredgers, a limited thickness of the fill deposits will require more frequent relocation of the dredger. This will adversely affect the production rates and, hence, the economics of the dredging operations. 

Although the final choice with respect to the execution method also involves other aspects such as project planning, economics, hydrographic conditions, availability of plant, distance between borrow and reclamation area, local regulations and legislation, reliable geotechnical information on the proposed borrow area and fill material is crucial for a Contractor to select the most appropriate dredging tools. 

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