A missing Spanish boy's rescue from a borehole "could take days," Juan Lopez Escobar, an engineer in the rescue team working to get him out, told Euronews.
An enormous search and rescue operation is underway to try and find Julen, 2, who was reported to have been out walking with his family in the small town of Totalan in Malaga on Sunday afternoon when he fell down the narrow 107-metre-long-hole.
Engineers are designing both a vertical and a horizontal tunnel to try and reach the boy.
The hole is 25cm in diameter and more than 100m deep.
The tunnels are meant to allow specialised mineworkers to go into the hole where the toddler is believed to have fallen.
But construction won't be easy, according to Lopez.
"The tunnels, which normally take months to make, will be dug in days," said Lopez, and moving machinery around the site is "very complicated,".
The engineer added that it will also be time-consuming to find out the type of terrain they are working with.
"Just probing the terrain and preparing the platform to work on takes 48 hours, while the speed of the excavation depends on the type of terrain - whether it's loose soil or hard rock."
Lopez said that the last phase of the excavation will have to be done manually with picks to avoid landslides that could put the child and rescue team in danger.
