More than 20 test pits are being dug along a beach to survey the state of sea defences.
Contractors are expected to take a month to complete the work along the Prom at Hunstanton.
West Norfolk Council, which is responsible for maintaining the defences between the Sea Life Centre and start of the cliffs, said the holes would allow engineers to inspect the condition of the seawall foundations.
Once each inspection is complete, the pits will be filled in again.
In a briefing paper, the council said the work was not related to ongoing concerns over the state of the shingle ridge to the south of the town.
Restrictions on access to parts of the ridge, including a ban on dogs, have been proposed to prevent erosion.
So far this financial year, the council has spent just over £98,000 on repairs to Hunstanton's defences, including patching concrete and replacing handrails. Last year's repairs cost £183,000.
Parts of concrete groynes are also being removed from some areas of the beach because they are no longer effective at preventing erosion because of changing coastal currents.
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