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Click on image below to enlarge |
The sludge from the hole indicates the rocks drilled in sequence. The outer drilling waste is coloured orange, indicative of the 24 metres of weathered upper basalt. Then follows 12 metres of hard grey basalt, after which this hole entered highly fractured basalt - an interval of 4 metres, directly above clays and gravels on soft bedrock at depth 40 metres. The wet layer is between 36 and 40 metres. The upper photo is of a diamond drill rig which was set up over the hole bored to 49 metres by the (red) percussion rig, in other photo, to deepen the hole.All known underground workings were thought to be to the west of this bore-hole position. The objective of this extension was to confirm secure ground exists at depth here, below the weathered bedrock under the basalts. No workings were encountered to end of hole at depth 77 metres, supporting the choice of site selected for the TSF. |
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