Because of problems with the sand injection system on 13 June, the 

 sand was injected from the ocean surface. It was never positively located 

 again. 



Prior to injection on 20 June, the operation of the injection system 

 was observed underwater using scuba, and the procedures were somewhat 

 modified. During the same period the detector vehicle was also observed 

 underwater and its tracking characteristics under slow speed (U-6 feet 

 per second) noted. Injection of Uo liters of xenonated sand on 20 June 

 was made as a line source. It was tracked intermittently for 2 days but 

 no intelligible interpretation of the dispersal pattern could be made. 



Utilizing experience gained during the preceding days, the xenonated 

 sand injected on 21 June was placed directly on the bottom as a point 

 source. It was traced for 2 days before field operations ended on 23 June. 

 Figures 23 through 25 show the isoactivity contours corrected for back- 

 ground and decay and illustrate the dispersal pattern for this test. From 

 these drawings it is not possible to make accurate determinations of the 

 rate of littoral drift, therefore the observed rate of tracer movement 

 cannot be compared with the rate of sediment movement computed from the 

 oceanographic parameters. However, it may be inferred that at this depth 

 (30 feet) and under existing wave conditions, the bulk of the sediment 

 was seaward of the equilibrium (null) point and moved offshore toward the 

 northwest. However, bottom current data was not available, and based on 

 the dispersal pattern, it might be concluded that, during the test, the 

 bottom current was flowing offshore to the northwest. Ingle (1966), 

 using fluorescent tracers, noted a somewhat analogous pattern at an 

 injection site (in 15 feet) near San Diego, and postulated a counter- 

 flowing bottom current . 



While, from a scientific standpoint, it would have been beneficial 

 to continue tracing the sediment movement, the primary objectives of the 

 program had been achieved. It was found that the sediment could be traced 

 for a period of days in an environment harsher than that experienced in 

 Florida, and field techniques had been brought to a fully operational'' 

 level . 



k. Point Conception, California, November-December 19^7 



The Point Conception - Government Point complex represents a sharp 

 change in the orientation of the California coastline (Figure ik) . Point 

 Conception and Government Point are both rocky promontories which extend 

 seaward from the general alignment of the coast (Figure 26). Bluffs and 

 extensive rocky areas on the bottom made this area more difficult to work 

 in than previous areas . 



This test represented an attempt to meet nearly all of the objectives 

 previously defined (see Section i). It provided additional knowledge of 

 operating characteristics of the equipment in the coastal environment, and 

 basic information which can be used to improve field procedures. In order 



39 



