Following that a sinkhole appeared above HS2’s Chiltern Tunnel on Saturday, the Chilterns Conservation Board (CCB), which conserves and enhances the Chilterns Area of Outstanding Natural Beauty (AONB), stated that due to existence of the unstable nature of fractured chalk, HS2 tunneling operations might lead to long-term permanent damage in the area.
According to the statement of CCB in its website, in a report published by the Chiltern Society in 2010 geologist Dr Haydon Bailey outlined the potential impact of tunneling, including a risk of ground collapse in areas with deep sections of weather chalk.
“Despite confident assurances by HS2 Ltd throughout the Select Committee process, proceeding approval of the HS2 Bill, and repeated assurances by their contractors since, the Chiltern Society, the Chilterns Chalk Stream Project, the Chilterns Conservation Board, and many local groups and individuals have continued to express their concern that tunneling operations will be extremely damaging. Unfortunately, our fears appear to be justified and we will now be urgently seeking answers and for appropriate action to be put in place to safeguard the landscape, wildlife and residents of the AONB,” the statement says.
Although HS2 told T&TI on Monday that investigations were undergoing, the sinkhole, which is above a completed section of tunnel, was likely to be linked to pre-existing ground conditions above the tunnels.
Responsibility of advancing the Chiltern Tunnel is up to HS2’s main works contractor, Align, which is a joint venture of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick. As the longest tunnel on the high-speed rail line, this tunnel is 16km long.