EH are doing everything they can as fast as they can - there is a meeting at the end of Feb.....the minutes will be posted around June at the earliest…
Personally, I know longer think their seeming inactivity matters as much as their threatened activity – which is far more dangerous because if they re-dig those tunnels they will add more faults than they can correct.
My personal opinion is that while the 68 tunnel is now known to be well compacted to a depth of 4m, beyond this there are voids but they are migrating very slowly towards the outside. We don't know how many or how large, but we do know that they are at great depth and the material above and to the side is holding it back and stopping it moving at any speed. Even if the voids did reach the surface the maximum area it can affect is less than the material from the trench they dug for the water pipe. I therefore think that as the risk is low there is enough time to attempt to monitor the stability whilst getting more comprehensive information about the voids over the next 5 or even 10 years. More information re grouting or improved compounds may become available in this time so this option should not be ignored, what needs to be stopped is research because the opportunity is supposedly there.
But what do I know, I'm pissed (and not a lady doing ladies' things; there is no nuts in the chocolate cake etc).
VBB