operated in seas up to 5 feet; at 6- foot seas it proceeded to Redondo 

 Harbor for shelter. 



The dredge was held in position with its beam to the sea by an arrange- 

 ment on the stern and bow lines. On the end of the dredge ladder was a 

 combination head that provided both cutting action and suction action. 

 The force to lift the suspended material was provided by a suction pump in 

 the well of the dredge, assisted by water jets powered by a separate 250 

 horsepower pump. Sand was removed by working the head down to the bottom 

 of the cut and keeping it in that position until the sandy material stopped 

 running to the head. The head was then raised and the dredge would pivot 

 about 40 feet to the next position in the cutting row, where the process 

 would be repeated. The dredge could cut a row 250 feet wide. At the com- 

 pletion of a row, the dredge was moved ahead on its lines about 40 feet for 

 the next row cut. 



For most of the project, it was possible to excavate to -55 to -65 

 feet, with a cut bank of 20 to 30 feet. This is desirable for high pro- 

 duction because it reduces moving and swinging of the dredge. 



The sand slurry was transported ashore through a combination pontoon 

 and submerged line. The pontoon line was a 16-inch diameter pipe supported 

 in 60-foot lengths by steel pontoons; each section was joined with a ball- 

 joint coupling. At every third coupling, a 15-foot-long rubber hose was 

 inserted to provide greater flexibility. The pontoon line was connected 

 to the dredge by a quick-release couple that allowed the dredge to be moved 

 swiftly to shelter if a storm arose. The submerged line was steel pipe 

 (with a wall thickness of 3/8 inch) joined to the floating line by a flex- 

 ible rubber hose. As the beach fill progressed, the submerged line was 

 moved by capping the shore end of the discharge, and then pumping water out 

 of the line. This created a floating pipeline that was towed to the next 

 discharge position. As pumping resumed, the pipeline filled and sank to 

 the bottom. 



The submerged line was connected to the beach fill pipe on shore with 

 a bolted connection. The fill was accomplished by a double-pipe system. 

 The system consisted of a yoke attached to the discharge line, and by use 

 of a double-valve arrangement, the discharge slurry was selectively distri- 

 buted to one pipe or the other or to both pipes simultaneously. 



The beach was built by placing the first discharge pipe at the desired 

 final elevation of the fill, in this case at +12 MLLW (Figure 6-26) and 

 pumping until the desired elevation was reached. During this pumping peri- 

 od, the second line was built parallel to the first. The valve controlling 

 the first line was closed and the valve to the second line was opened. The 

 first pipe was then advanced to the next discharge point. By alternating 

 between these two discharge lines, the beach width of 200 feet was built 

 to the full cross section as they advanced. (See Figure 6-27.) The final 

 placement totaled 1.4 million cubic yards at a cost of $1.5 million. 

 Between 4,000 and 15,000 cubic yards per day were placed on the beach, 

 averaging 8,000 cubic yards per day. Recent measurements indicated only 

 minor beach changes, and the beach has been relatively stable. 



6-33 



