For years now the anchors in Fish Caves have been concerning people, some being very wobbly!
As we needed to place the Radon monitors in the mine I decided to have a go at removing and replacing some of the worst looking anchors. Armed with a Hydrajaw anchor testing unit (with thanks from Pete Knight), and a selection of anchors donated following a practice session at Oaklands last year I set about the task.
2 anchors were removed (see video). Both looked terrible, in that both could be pulled out partially by hand. I expected them to come out easily, but that didn’t prove to be the case! The worst looking anchor needed a consistent pull at around 4kN to extract, at one point peaking at 11kN! The second peaked at 20kN at which point I stopped and had to drill into the resin around the anchors to remove it (which then required around 4-6kN to extract!)
Several other anchors wobble a little, however following the efforts to remove these 2 I left others in situ (worth noting that non of the slightly moving anchors are at pitch heads).
I also installed an additional anchor at the start of the traverse to the last pitch.
A new rigging topo (based on an original drawn up by Mat W. with the help of Jim B. has also been drawn up.
Fish Caves (Lead Mine)