excessive rate o£ return of dredged material to the channel from the 

 existing disposal areas, the tests were expanded to include studies of 

 alternate areas in the same general vicinity to determine if more suit- 

 able areas could be defined. For the disposal area tests, the gilsonite 

 water mixture was dumped into the disposal area in the model in a manner 

 to simulate prototype disposal operations. The daily prototype dredge 

 advancement rate was simulated in the model injection operation. 



(9) Summary of Test Results . At the Goose Hill shoal reach, 

 material was placed about 1,600 feet south of, and parallel to, the navi- 

 gation channel. The results of tests in which material was placed only 

 in the upstream half of the present disposal area (Fig. 3-60) indicated 

 that only a very small part of the material from this area returns to the 

 navigation channel. Test results for the downstream half of this disposal 

 area indicated a substantial return of material to the navigation channel 

 (Fig. 3-61). However, a test conducted in which the material was placed 

 in a proposed disposal area on the opposite (north) side of the channel 

 and it was found that no material returned to the navigation channel. 



g. Flushing — San Diego Bay . 



(1) Project . Proposed second entrance to bay. 



(2) Reference . Fisackerly (1974). 



(3) Laboratory . WES. 



(4) Test Period . May 1967 to September 1968. 



(5) Problem . At the present time, the only connection between 

 the Pacific Ocean and San Diego Bay is Zuniga Channel, located at the 

 northwestern end of the bay. Since the more recent navigation facilities 

 are located in the southeastern part of the bay, and more are planned for 

 the near future in that area, a second entrance would greatly reduce the 

 transit time through the bay for commercial vessels and would alleviate 

 some traffic congestion in Zuniga Channel. Because the flushing rate 



of San Diego Bay is extremely low, it was hoped that a second entrance 

 would expedite flushing and therefore improve the quality of the bay 

 water. 



(6) Purpose of Model Study . This study was conducted to deter- 

 mine the feasibility of, and the optimum location for, a second entrance 

 into San Diego Bay and the effects of such an entrance on the tidal 

 heights, current velocities, and circulation patterns throughout the 

 bay and in the second entrance. 



(7) The Model . The physical model used for this study repro- 

 duced all of San Diego Bay and a part of the Pacific Ocean outside the 

 bay (Fig. 3-62). The model was of fixed-bed construction and was built 

 to linear-scale ratios of 1:500 horizontally and 1:100 vertically. The 

 model was 125 feet long, 100 feet wide, and covered an area of about 

 12,000 square feet. 



48 



