contour, is a rubble-mound structure with a crest elevation 14 feet above 

 mean lower low water. Its location and orientation enable it to trap 

 almost all of the downcoast littoral drift. The breakwater provides pro- 

 tection from waves for the dredge and for the small craft entering the 

 harbor. The rubble-mound entrance jetties have a crest elevation of 14 

 feet above mean lower low water, and extend to about the 14-foot isobath. 

 They prevent shoaling of the entrance channel which has a project depth 

 of 20 feet. 



A floating dredge has cleaned the trap periodically since 1960. In 

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

 phase of harbor development provided about 6 million cubic yards of sand. 

 In 1963, 2 million cubic yards were dredged; in 1965, 3 million cubic 

 yards were transferred. In the Port Hueneme operation (Section 6.521), 

 2 million cubic yards were transferred in 1953. This total of 13 million 

 cubic yards had stabilized the eroded downdrift shores by 1965. Since 

 1965, bypassing has continued at intervals of about 2 years. 



6.523 Santa Barbara, California. (Wiegel, 1959). The Santa Barbara sand 

 bypassing operation was necessitated by the construction of a 2, 800- foot 

 breakwater, completed in 1928, to protect the harbor. (See Figure 6-47.) 

 The breakwater resulted in accretion on the updrift side (west) and ero- 

 sion on the downdrift side (east). Bypassing was started in 1935 by 

 hopper dredges which dumped about 202,000 cubic yards in 22 feet of water 

 about 1,000 feet offshore. Surveys showed that this sand was not moved 

 to the beach. The next bypassing was done in 1938 by pipeline dredge. 

 A total of 584,700 cubic yards of sand was deposited in the feeder beach 

 area shown in Figure 4-47. This feeder beach was successful in reducing 

 erosion downdrift of the harbor, and the operation was continued by 

 placing 4,475,000 cubic yards periodically from 1940 to 1952. 



The city of Santa Barbara decided in 1957, not to remove the shoal 

 at the seaward end of the breakwater, because it provided additional pro- 

 tection to the inner harbor. A channel is being maintained around the 

 inshore end of the shoal by a small floating dredge. Wave and weather 

 conditions limit operations to about 72 percent of the time. With a capa- 

 city of about 1,600 cubic yards per 8-hour shift, dredging is adequate on 

 a yearly basis, but inadequate to prevent some shoaling of the channel 

 during storms. 



6-63 



