Is your town at risk from sinkholes? Geologist explains how chalk mining caused Sudbury sinkhole in Newton Road
14:34 16 February 2017
A gaping sinkhole has caused nearly a month of traffic chaos in a Suffolk town, but one expert has said many other areas in the region are at risk from the often destructive environmental phenomena.
Newton Road in Sudbury is still closed after an eight foot wide and two foot deep hole opened up on the busy main road on January 20.
The hole was caused by a burst water main – which Anglian Water repaired – however, the first attempt at restoring the road surface failed almost immediately and the road was closed again. It is now due to open on Friday February 17.
Geologist Tom Backhouse, from consultants Terrafirma, said while the water main aggravated the collapse, old chalk mining in the area around Newton Road was the likely cause.
He said: “The recent ground collapse at Newton Road, Sudbury was very likely indirectly linked to historical underground chalk extraction from the mid to late 19th Century.
“Chalk mining is recorded to exist within 250 metres of the ground collapse and has historically caused subsidence in the local area – notably at Pot Kilns School (Great Cornard) and Maldon Court.
“Chalk mining in Sudbury is a result of extensive brick making in the town that occurred during the 18th and 19th Centuries, where chalk was an essential ingredient in the industry locally and nationally.
“Chalk was often quarried at surface until overburden or land boundaries were reached, from which point, it was mined. In Sudbury, the chalk disappears beneath the Thanet Sand and it is from here that the known chalk mining occurs and is suspected to have taken place beneath Newton Road.
“In Sudbury and in numerous other urban locations, ageing utilities infrastructure is commonly triggering the collapse of shallowly mined mineral workings.”
He said several areas in Suffolk, the East of England and the wider south east are at risk from collapse due to chalk mining.
He said any areas where there has been a history of brick making could be under threat of mining-related subsidence or collapse.
The most at risk areas are on the outskirts of historic towns, which have later been developed on, such as in Sudbury, Bury St Edmunds, Thetford and Norwich.