pipeline dredge was added in 1956. The fixed plant was destroyed by a storm 

 in 1962, and the inlet essentially closed, allowing the sand to bypass 

 naturally. In 1968 the inlet was again improved with the construction of a 

 jetty and a breakwater connected to the shore by a sand weir (see Fig. 6-42). 



The weir jetty impoundment basin was never fully dredged initially, and 

 the 25-centimeter dredge operations were hampered by wave action. From 1968 

 to 1972, sand bypassing was achieved by dredging material from the channel and 

 back bay and pumping it to the downdrift beaches. In 1972, 76,000 cubic 

 meters (100,000 cubic yards) of sand was removed from the impoundment basin. 

 By 1975, the basin had refilled with littoral material, and bypassing was once 

 again performed as before by the 25-centimeter dredge. Also in 1975, an 

 experimental semimobile bypassing system was installed to bypass sand from the 

 weir impoundment basin to the downdrift beach. 



This system consists of two jet pumps attached by flexible rubber hoses 

 to the steel pipes, which are supported on pilings in the impoundment basin 

 (see Fig. 6-42). The steel pipes are connected to the pumphouse where two 

 centrifugal pumps, having a combined nominal capacity of 115 cubic meters (150 

 cubic yards) per hour, discharge through a 20-centimeter pipe to the downdrift 

 beaches. The jet pumps are pivoted about the ends of the steel pipes by 

 cables from the shore. This enables the pumps to reach a large area of the 

 impoundment basin. 



During the first 6 months of operation, 60,400 cubic meters (79,000 cubic 

 yards) of sand was bypassed from the impoundment basin by the jet-pump system, 

 and approximately 23,000 cubic meters (30,000 cubic yards) was bypassed from 

 the channel and impoundment basin by the floating dredge. Once operational 

 procedures were established, the system could be successfully operated by a 

 three-man crew in nearly all wave climates. 



Since late 1975 the system has been owned and operated by local author- 

 ities who estimate the pumping capacity at 38 cubic meters (50 cubic yards) 

 per hour and the effective pumping time at about 113 hours per month. The 

 U.S. Army Engineer Waterways Experiment Station (WES) estimates the long-term 

 pumping capacity at about 75 cubic meters per hour, assuming both pumps are 

 operating. This estimate is based on the operating times from the first 6 

 months of operation. Using these two estimates as limits and assuming year- 

 round operation, the system can pump between 51,800 and 103,700 cubic meters 

 (67,800 and 135,600 cubic yards) per year. The estimated yearly littoral 

 drift at Rudee Inlet is between 53,500 and 92,000 cubic meters (70,000 and 

 120,000 cubic yards). 



2. Floating Bypassing Plants . 



Sand bypassing has been achieved by floating plants at all five types of 

 littoral barriers (Fig. 6-39). Those operations that are discussed and illus- 

 trated in this section are listed below: 



(a) Type I: Jettied inlet — location at Port Hueneme, California (Fig. 

 6-43). 



(b) Type II: Inlet sand trap — locations at Jupiter Inlet, Florida 

 (Fig. 6-44), and at Sebastian Inlet, Florida (Fig. 6-45). 



6-59 



