During the period of the test (21-23 June 1967), sea conditions at 

 Surf, California, averaged 3 to k feet from the northwest. Deepwater 

 waves (swells) averaged 7 to 8 feet from the northwest (305°) and had an 

 average period of 10 seconds. (See Figures 21 and 22.) Based on these 

 conditions, the bottom orbital velocity (U m ) was calculated by: 



U m = it H/T sinh Kd 

 where H = wave height 



T = wave period 



d = depth of water 



k = 2tt/L 



L = wave length 



and found to be 109.6 centimeters per second for the 30-foot water depth. 

 This value was believed to be more than sufficient to cause sediment move- 

 ment considering that from Hjiilstrom's curve a velocity of 18 centimeters 

 per second is required to suspend particles of 2.0| (.25 millimeters), 

 the mean particle diameter of injected sand at this site. It should be 

 noted that the average grain size at 30 feet is 2.65<j> (.16 millimeters), 

 which would require a velocity of 21 centimeters per second for suspension. 

 Following the approach used by Bagnold (19^7) and Vernon (1965), the 

 sediment migration rate was calculated as 1/3 the water drift velocity 

 (u) where : 



_ 5 

 u = k 



(2d 



,2 C when d<L 



and in which u = water drift velocity along seabed 



" C = wave velocity 



Based on oceanographic conditions for the period 21-23 June 1967, the 

 sediment movement rate (l/3 u) was determined to be 7-7 centimeters per 

 second (910 feet per hour). 



For the test at Surf, three large injections were made offshore in 

 approximately 30-foot depth: 



Date 

 13 June 



20 June 



21 June 



Amount 

 80 liters 

 1+0 liters 

 U0 liters 



Activity 

 1+.5 curies 

 0.1+5 curies 

 0.25 curies 



37 



