The dig is well supported and quite sound.
Through the dig (& from memory, as it was some time ago), the sump crossed by rails, mentioned on Mikes website goes down about 60ft to a short section of level, still railed, but collapsed both ways.
The wet shaft, we maypoled, to a short level, walled up at the end with small sections of iron pipe sticking out? Don't think anyone had been up there as there were no modern boot prints and a couple of clay pipes on a ledge. The shaft continued up, but from what I remember, the roof of the level prevented us positioning the pole to gain much further height.