Drilling of observation and test bores commenced with one plant on 28th September 1962. Later, on 13th November, a second plant commenced operations. The first 8 holes were test bores to determine the thickness of the aquifer in the vicinity of the existing trench. Later, observation bores were established at distances of up to four miles from the trench. Most of these were drilled in the vicinity of old test bores. A total of 35 observation bores have been drilled to date and 2 are in progress. For several weeks at the end of the period both plants have been used to drill blast holes along the line of the new trench, at 12 feet intervals. By the end of the period approximately 40 blast holes to an average depth of 20 feet will have been drilled. The plan accompanying this report shows the location of observation bores drilled to date.