Yep. Interesting.
So, combining that with rainfall data (accurate) it would be possible to estimate the pumping requirements to dewater the original workings inside a number of weather assumptions...
It made me think about how the old men were put to work in Gwennap digging out drainage culverts, gutters, etc to minimise the rain soaking in/pumping costs. Given the nature of the roads/buildings, I imagine the stormwater is actually drawn off making it a lot drier than could be expected....most certainly a hell of a lot more than Jane.