Other structures for navigation purposes and for close inshore break- 

 water and pier facilities have successfully used similar principles in 

 their construction. Caisson foundations used for bridge construction 

 are also similar, but are often basically open-bottomed and sunk by 

 excavation through the unit itself. 



The laying of tube sections in a dredged trench with subsequent back- 

 filling is becoming more popular in tunnel construction. Tunnel sections 

 are prefabricated onshore with sealed ends, towed to location, sunk, 

 connected to the previously laid part, and then covered and finished. 



While none of the above techniques exactly reproduce the technique 

 proposed by this study, the concept of fabricating large units onshore 

 or in a drydock, outfitting at a protected pier site, towing to location 

 in open water and sinking into place as shown in Figure 5, are routine 

 construction procedures. Certain adaptations are always necessary to 

 allow for particular draft requirements, such as onsite bottom conditions 

 and connection and anchoring needs, but these present no real problem 

 to presently available construction techniques. 



Model studies recommended for the design phase of the work may be 

 helpful in developing or adapting major construction techniques and 

 construction equipment. Possibly, the same model tests conducted for 

 the design studies, with some slight modification, can be used to provide 

 additional data for the efficient design and use of construction equip- 

 ment. 



2. Overall Program . 



The construction program is based on established procedures well 

 proven on earlier projects. Because work is being done under similar 

 conditions in the open sea, and considering the current capability and 

 ingenuity of the construction industry, provision for the operations 

 necessary for this study represents development of present practice. 

 Therefore, an efficient and economical construction scheme can be laid 

 out for the project under study. 



In planning the construction phase to establish an offshore break- 

 water-oil storage system, various possible construction procedures were 

 carefully considered. 



Once the general design was determined, specific requirements dictated 

 by flotation characteristics, towing and positioning methods, preparation 

 of prefabrication sites and final installation site, were carefully 

 reviewed before proceeding to a final design. These factors influenced 

 the final design, and formed the basis for estimated construction sched- 

 ules and costs. 



Factors considered in this area of the study are: 



