Dorset landslip: Holes drilled around Beaminster Tunnel
Engineers are to begin assessing the stability of a hill around a road tunnel in Dorset after a landslip in which two people died.
Rosemary Snell, 67, and Michael Rolfe, 72, from Somerset, were found at Beaminster Tunnel after their car was engulfed.
The investigation, which involves drilling 25m (82ft) holes, could pave the way for the tunnel to be reopened.
Miles Butler, from Dorset County Council, said work starts on 22 August.
He added: "While I understand local people want a quick solution, we need to make sure that we carefully consider the alternatives."
The tunnel has been closed since the landslide blocked the road on 7 July. Engineers said there was a risk of further slips.
Once the drilling samples have been analysed, an assessment on the stability of the hillside is due by the end of September.
Ms Snell and Mr Rolfe went missing on 7 July but it was not until nine days later that Avon and Somerset Police alerted colleagues in Dorset the couple had been traced to the Beaminster area.
The vehicle, a silver Skoda, was completely crushed under several hundred tonnes of water, mud, bricks and trees.
The Independent Police Complaints Commission (IPCC) is to oversee an Avon and Somerset Police investigation into the way the couple's disappearance was handled.
The IPCC has said it was happy with the way Dorset Police handled the case.
Police said at the time of the landslip it was not known anyone was missing.
The A3066 road, which runs through the tunnel, is one the main routes through West Dorset.