HS2 contractor to investigate sinkhole discovered above rail tunnel in Bucks

The contractor working on the HS2 rail project is investigating a sinkhole which has emerged above a rail tunnel in Buckinghamshire.

Great Missenden Parish Councillor Catherine Bunting alerted residents to the gaping hole next to the lake at Shardeloes near Amersham.

Councillor Bunting said on Twitter: “We all know the chalk aquifer is fragile, but HS2 and the investors behind it don’t care. How many warning signs till it’s stopped?”

Since the councillor’s viral Tweet HS2’s contractor, Align, has confirmed it is investigating the issue.

Residents received an email from the contractor, which has been published by The Guardian, stating: “It’s quite sizeable – around six meters in diameter and five meters deep. These are approximate measurements.”

It has been cordoned off and sits above part of the Chiltern tunnel being constructed as part of the HS2 project.

A spokesperson for HS2 Ltd said: "We are aware of a small area of ground movement within a field above the Chiltern tunnels. Investigations are ongoing, but this is likely to be linked to pre-existing ground conditions above the tunnels. The site has been sealed off and there is no risk to the public."

Campaigners have shared the councillor’s video on social media stating it is “time to stop digging”.

In total the Chiltern Tunnel is estimated to be 10 miles long and has been developed by large tunnelling machines which have been excavating land in the Chilterns for nearly two years.

When the tunneling project reached its halfway point in Bucks in February, Martyn Noak, HS2 Ltd’s head of tunnel engineering, said: “This tunnel will take HS2 underneath the Chiltern hills, safeguarding the woodlands and wildlife habits above ground as well as significantly reducing disruption to communities during construction and operation. Once complete, HS2 will offer low carbon journey options linking London with the major cities of the north and releasing capacity for more freight and local trains on our existing mainlines.”

As well as digging and lining the tunnels, engineers have also completed the excavation of five shafts that will provide ventilation and emergency access near Chalfont St Peter, Chalfont St Giles, Amersham, Little Missenden and Chesham Road.