Small promenade sinkhole has vast void underneath

Investigations have shown a small sinkhole that appeared on a Norfolk beach promenade leads to a much bigger void underground.

The Borough Council of King's Lynn and West Norfolk said it was creating a repair plan for the walkway on Hunstanton seafront after the hole was discovered last week.

Its environmental health manager, Dave Robson, said ground penetrating radar surveys were done and the void measured 3.5m (11.4ft) deep and 14m (45.9ft) wide in places.

Until it can be fixed, a 140m (1450ft) area between the Waterside Bar and Oasis leisure centre, and part of the beach, have been closed off.

Robson warned that continuing high tides and bad weather would make repairs difficult.

Six kiosks selling refreshments and souvenirs have been affected by the closure, but only one was due to open this half-term. The council said an alternative pitch had been found.

Hunstanton's promenade dates back to the 1920s.

Material used at the time to build it, including bottles and pottery, have been found on the beach exposed by the undercutting of the sea.

It was renewed in the 1954 after flooding washed away much of the walkway.

That material is now being damaged by the sea too, as sand levels lower and the footings of the promenade get exposed.

Last August, the council said more than 300 concrete slabs on the promenade could need replacing, and a 10-tonne vehicle weight limit was imposed.

At the time, the authority found sections of the sea wall, including those near the Oasis and the pier, were at risk of structural failure and the promenade surface was reaching the end of its life.

The authority previously said work to repair the whole prom could take more than two years and cost "multiple millions".

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