April 14 through April 30, 1964
by Erik Stephansen, OSESA


The Benoto drill began full scale operations at the outset of this report period. The machine has performed very well although the sampling rate is considerably slower than first anticipated. The drill completed one sample line during the two weeks, specifically 7 holes with 4 samples accepted by the geologic department.
Although the actual sampling operations with the Michigan-Caisson unit is functioning well, the number of holes completed during this period was low because of (1) severe surf conditions which necessitated an extension of the suction carriage; (2) mechanical failure, and (3) moving the sampling unit to a site 20 miles farther north.
Consultants from Anglo American inspected the Michigan and Benoto operations on 20th-21st April. As a result of Anglo American - C.D.M. discussions on 22nd April, it was decided to order two more Benoto drills and to increase the operating time on both the Michigans and the Benotos.


Benoto Drill As summarized in the progress report for the preceding two weeks period, the Benoto drill has been tested and the crew trained on several holes in the vicinity of Central Fields. On Monday 13th April, the Benoto was moved to site U-2, about 10 miles from Central Fields. After assembling the drill and getting the machine into position, actual sampling began 14th April. The operation progressed well until a layer of conglomerate was struck at a depth of 30 feet. An additional day was spent attempting to penetrate the conglomerate. Because of contamination which occurred during penetration of the conglomerate, and because of other technical problems, it was decided not to complete this hole. The second hole was begun on Thursday and completed on Friday 17th April, but was rejected by the geologists because of contamination. On Saturday the third hole at this site was begun and the equipment performed smoothly. The hole was completed by the end of the day and one diamond was found in this sample.
As the crew became more experienced the operation of the drill progressed more smoothly; the sampling programme during the second week of this reporting period went quite well. Four additional holes were completed at this site. No more diamonds were found however.
Upon completion of this site, line U-2, the Benoto drill was shifted back to the Central Fields workshop to have sand tyres mounted. The mounting of the tyres will require approximately one week.
Although the Bonoto drill has performed well in actual sampling operations, its rate of sampling is decidedlty slower than had been originally anticipated. It is unlikely that the drill can complete more than one sample per day.

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