It was decided that core sampling would probably not be possible 

 and if it were, the samples would produce no definite measure of the 

 effectiveness of the sealing. A few exploratory holes were made with the 

 wagon drill between grout holes, and most showed that the voids penetrated 

 were filled as expected. Prior to commencement of work, flourescent dye 

 was placed on the ocean side of the jetty and the time required for colored 

 water to show upon the opposite side was recorded. This required from 10 

 to 20 minutes. After sealing, the test was repeated and in only one place 

 did color come through the jetty. Investigation of this spot proved the 

 existence of non^-continuity of the barrier which was corrected by drilling 

 another grout hole and intruding additional grout. 



Before sealing started, there was a trench-like depression in the 

 beach contiguous to the outside (away from the channel) toe of the jetty, 

 where beach and jetty met. This depression was about 10 feet wide and 

 about 2 feet deep near the mean high water line, becoming progressively 

 shallower and fading out at about 2 feet below MLLW (see fig. 2 and 

 photograph U) # This was an ostensible indication that sand was passing 

 through the jetty. As sealing progressed seaward, the depression filled 

 and sand piled against the jetty to heights up to 1.5 feet above the 

 average beach. Also, the beach as far as l£0 feet away from the jetty 

 began to gain in elevation. This seemed to be convincing evidence that 

 the sand was now being stopped from moving through the jetty. 



Batching control . - The wheelbarrows were calibrated and used as 

 measuring boxes for the sand, loads being struck at all times to assure 

 uniformity. This method was of sufficient accuracy as the moisture content 

 of the sand was small and remained nearly constant. Water was measured by 

 a meter installed on the mixer. Cement was supplied in bags of 9h pounds, 

 and clay in bags of 100 pounds. The mix was set up so as to avoid using 

 partial bags. Proportions used are as tabulated below. Two pounds of 

 calcium chloride per sack of cement were added to accelerate the set. 



One cubic yard mix 



Sand 2,000 pounds 



Cement, 8 sacks 752 pounds 



Clay, U sacks.... U00 pounds 



Water 8.6 cubic feet 



Calcium chloride......... 16 pounds 



These proportions differ from those shown for No. 8 of the tests, but it 

 was desired to use only enough clay to produce the required plasticity in 

 order that the concrete would be as hard as possible. This mix was ideal 

 for most conditions encountered although it caused the pumps to work at 

 their utmost. 



Placement control . - Placement of grout was always observed closely. 

 Withdrawal of the nozzle was adjusted by observing the migration of the 

 grout as described earlier. In cases where it was impossible to see the 

 grout at all, the hole ahead of the one receiving grout was probed for 

 appearance of grout. Grout was usually allowed to build up tto about 3 

 feet in depth in the hole ahead before withdrawing at a location and 

 moving forward. 



