Just have a cycle around the top of tresevean far corner of the elctricity sub station, I came across 2 shafts I had not seen before. one being a metre or so of raised cicle or collar with approx 6inch inverted vent pipe.
the other shaft , much more interesting , in the middle of a small pond. a raised concrete structure with veiwing cage at either side .Hard to see anything though, the camera flash came in usefull. This covers a large square shaped shaft, as far as I could see concrete lined to quite a depth. having to retarce my route to find my usual depth gauge ,"boulder"
Probably the deepest shaft I have come across seems vertical to quite a depth. I seem to remember that tresavean had the second deapest shaft in cornwall. could this be the one?
Any ifo appreciated