Observations 



The underwater detector system appeared to be very stable in the surf 

 zone, and broadside breakers had little effect on its tracking ability. 

 The 80-keV gamma rays from the 133 Xe-tagged sand were detected with 

 reasonable efficiency; counts in the tens of thousands per second were 

 observed. The system was stable, and all detectors functioned properly. 

 No malfunctions were observed in the sand-pumping device. The sea con- 

 ditions were mild, with ocean swells ~1 ft high. The tagged sand ap- 

 peared to be in patches that formed a pattern. Liberal interpretation 

 (since the survey was very limited) of the data revealed & series of 

 waves running perpendicular to the beach. No significance was placed 

 on this interpretation in regard to sand transport mechanisms. 



Alterations Indicated by Test 



Since it was known that large rocks are located near the area selected 

 for the next test (Surf, California), it was decided to utilize a weak 

 link in the tow cable so that the link would break if the detector 

 assembly became lodged in the rocks. Breaking of the link would allow 

 additional tow cable to play out and thus give the LARC operator time 

 to stop. Also, it was recognized that sea conditions would be less 

 favorable at Point Conception, California (the last test), and plans 

 were formulated to provide a metal cabin shelter for the instruments, as 

 well as for housing all the on-board equipment, to afford some protection 

 from ocean spray. 



SURF FIELD OPERATION (JUNE I967) 



Purpose 



The operation at Surf, California, was a full-scale sand-tracing experi- 

 ment conducted in order to test all developmental components and to 

 establish operational techniques for handling 5S-kg quantities of tagged 

 sand. This area was chosen because all access is controlled by the U. S. 

 Air Force and because future requirements at Vandenberg Air Force Ease 

 indicate a need for additional information concerning sand transport in 

 the area. 



Operational Procedure 



Considerable difficulty was experienced in making the first ll6-kg 

 injection. Tagged sand in the hopper of the injection device became wet 

 with ocean spray and would not flow properly; therefore the sand was 

 dumped into the water from the surface. Because of ocean currents this 

 caused the sand to disperse over a large area, and only background radia- 

 tion levels were detected. For the next injection the sand-pumping de- 

 vice was again used, but in a slightly different manner: the sand was 

 pumped to the bottom in a water slurry. Here again, however, very little 



C- 13 



