A sinkhole has been discovered in Hyde Heath, near Amersham, not long after a six-metre sinkhole appeared in the town earlier this year.
The sinkhole in Shardeloes appeared during HS2 drilling works in May, but wasn’t filled in until September.
This led to councillors raising concerns over the high-speed railway project, which includes the creation of the Chiltern Tunnel underneath Amersham.
Now, it has been confirmed that the sinkhole in Hyde Heath, which appeared on November 9 and has temporarily rendered a public bridleway unusable.
Upon communicating with Hs2, cllr Williams has confirmed that a tunnel boring machine was making its way through the ground under Hyde Heath when the sinkhole emerged.
Cllr Williams said: “The area around the hole is closed with 24/7 security in place. We are continuing to hold Hs2 to account through regular weekly meetings and public safety is our first priority.”
Hs2 have apparently been “at pains” to emphasise that its tunnel boring machines do not usually drill at such shallow depths, close to the surface of the ground. It was due to the chalky constitution of the soil below Hyde Heath, cllr Williams was told, that the machine ended up creating a sinkhole.
Although Hs2 conducted geological surveys before the drilling began and even advised farmers to move horses grazing near Hyde Heath elsewhere, the production of the sinkhole has been lampooned as an affront to public safety.
A spokesperson for Hs2 said: “There is a known geological fault in the area and after seeing data from the tunnel boring machine which gave an indication of a potential feature, we informed the landowner and put extra monitoring in place at the surface before the sinkhole appeared.
“We have been engaging with all key stakeholders including Buckinghamshire Council, Affinity Water and the Environment Agency, throughout the excavation of the Chiltern tunnels and we will keep them updated as we go forward.”