entrance to the downdrift beach through a submerged pipeline. The unique 

 feature of this operation was that the outer strip (or seaward edge) of the 

 impounded fillet was used to protect the dredge from wave action. Land equip- 

 ment excavated a hole in the beach, which was enlarged to permit a large 

 dredge to enter from the open sea. 



Since it was necessary to close the dredge entrance channel to prevent 

 erosion of the protective strip, water had to be pumped into the dredged 

 lagoon. This problem might have been avoided had the proposed entry route 

 from inside the harbor been used and kept open during phase I dredging (see 

 Fig. 6-43). 



After completing the phase I dredging (see Fig. 6-43), the floating plant 

 then dredged the protective barrier by making diagonal cuts from the phase I 

 area out to the MLLW line . 



From August 1953 to June 1954, 1,554,000 cubic meters (2,033,000 cubic 

 yards) of sand was bypassed to downdrift feeder beaches. Subsequent develop- 

 ment updrift at Channel Islands Harbor, discussed below, provided periodic 

 nourishment to the downdrift beaches southeast of Port Hueneme Harbor. 



b. Channel Islands Harbo r, Ca lifornia (Herron and Harris, 1967). This 

 small-craft harbor was constructed in 1960-61 about 1.5 kilometers northwest 

 of the Port Hueneme entrance (see Fig. 6-46). The type III littoral barrier 

 consists of a 700-meter-long (2,300-foot) offshore breakwater, located at the 

 9-meter-depth contour, and two entrance jetties. The breakwater is a rubble- 

 mound structure with a crest elevation 4.3 meters (14 feet) above MLLW. It 

 traps nearly all the littoral drift, prevents losses of drift into Hueneme 

 Canyon, prevents shoaling of the harbor entrance, and provides protection for 

 a floating dredge. The sand-bypassing dredging operation transfers sand 

 across both the Channel Islands Harbor entrance and the Port Hueneme entrance 

 to the downdrift beaches (U.S. Army Engineer District, Los Angeles, 1957). 

 The general plan is shown in Figure 6-46. 



In 1960-61 dredging of the sand trap, the entrance channel, and the first 

 phase of harbor development provided 4.6 million cubic meters (6 million cubic 

 yards) of sand. Since the initial dredging, the sand trap has been dredged 

 10 times between 1963 and 1981, with an average of 1,766,000 cubic meters 

 (2,310,000 cubic yards) of sand being bypassed during each dredging operation. 

 The 22.2 million cubic meters (29 million cubic yards) bypassed since opera- 

 tions began has overcome the severe erosion problem of the beaches downdrift 

 of Port Hueneme. 



c. Jupiter Inlet, Florida (Jones and Mehta, 1977). The type II sand 

 bypassing method consists of dredging material from shoals or a sand trap 

 located in the protected waters of an inlet or harbor entrance and discharging 

 the spoil onto the downdrift beaches. 



Jupiter Inlet is an improved natural inlet located in the northern part 

 of Palm Beach County, Florida. Maintenance dredging of the inlet has been 

 performed since the early 1940' s, but bypassed amounts before 1952 are 

 unknown. Between 1952 and 1964 dredging of the inlet produced approximately 

 367,900 cubic meters (481,200 cubic yards) of sand which was bypassed to the 

 downdrift beaches south of the inlet. Since 1966 most maintenance dredging 



6-72 



