I thought this work was due to the illegal dumping as newforester says. I also thought this was what was causing the subsidence rather than trees which in general stabilise soil. I watched diggers pulling down matyre trees a couple of weeks ago there. I thought farmers were paid not to cut hedges during bird nesting season so I do not understand how mature tres can be pulled down by diggers at this time. Perhaps if they needed to do this they could have done it in February.