(1) Exposure of Plant to Wave Action . Wave action limits the effec- 

 tive operation of a floating dredge; the exact limitation depends on the plant 

 type and size, and the intensity of wave action. This factor is particularly 

 critical if the dredge will be exposed to open waters where high waves may be 

 expected. No standard criteria are available for the maximum permissible wave 

 action for operation of various types of dredges. Such data must be obtained 

 from dredge operators who are familiar with the dredge plant and the area in 

 question. However, as mentioned in Chapter 6, Section III (PROTECTIVE 

 BEACHES) , a specially designed pipeline dredge has been used successfully in 

 an exposed location at Malaga Cove (Redondo Beach), California, for pumping 

 sand from offshore to the beach. Hopper dredges may be operated in higher 

 waves than the other types of floating dredge plants but cannot be safely 

 operated in very shallow water. Pipeline dredges can operate in shallower 

 water, but when exposed to hazardous wave action are subject to damage of the 

 ladder carrying the suction line, breakage of spuds, and damage of the 

 pontoon-supported discharge pipe. Thus, estimates must be made of the 

 probable operational time with and without manmade structures or natural 

 ground features to protect the dredge and auxiliary equipment. Determining 

 the time of year when least wave action will prevail will provide a basis for 

 estimating plant operation under the most favorable conditions. Also, the 

 protection of the plant during severe storms in the area of the project must 

 be considered. 



(2) Plant Capacity . The use of a floating dredge with a specific 

 capacity is generally controlled by economic consideration. If the impounding 

 zone of a littoral barrier is large, a periodic bypassing operation may be 

 considered in which a large plant is scheduled and utilized for short periods 

 of time. An alternative would be the use of a small-capacity plant for longer 

 periods of time. If long pumping distances to the discharge point necessitate 

 too many booster pumps, a larger plant may provide the most economical opera- 

 tion. The choice sometimes depends on availability of plant equipment. 



(3) Disc harge Line . The discharge line considerations are the same 

 as those given for land-based dredging plants. 



c. La nd-Based Vehicles . Local site conditions may favor the use of 

 wheeled vehicles for bypassing operations. Typical factors to be considered 

 and evaluated would be the existence or provision of adequate roadways and 

 bridges, accessibility to the impovmding zone by land-based equipment, the 

 volume of material to be bypassed, and the time required to transport the 

 material. Factors involved in locating deposition areas are also the same as 

 discussed under land-based dredging plants. 



3. Legal Aspects . 



The legal consequences stemming from any considered plan of improvement 

 are many and complex. Legal problems will vary, depending on the physical 

 solution employed as well as the jurisdiction in which construction is to 

 occur. The complexities of the legal problems are due not so much to the fact 

 that legal precedent will differ from jurisdiction to jurisdiction, but rather 

 from the application of any given factual setting to a particular body of law. 

 It should also be noted that insofar as the Federal Government is concerned, 

 liability for personal or property damage will be determined by reference to 

 the Federal Tort Claims Act. 



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