Drilling began on Hampstead Heath last week as technicians started a ground investigation programme in preparation for the controversial dam rebuilding project.

Ham & High: Drilling technicians use a cable percussion rig to take soil samples between the Kenwood Ladies' Bathing Pond and the Bird Sanctuary Pond. Picture: Polly HancockDrilling technicians use a cable percussion rig to take soil samples between the Kenwood Ladies' Bathing Pond and the Bird Sanctuary Pond. Picture: Polly Hancock (Image: Archant)

Staff from engineering contractor Bam Nuttall moved in with boring equipment, including a large cable percussion rig, and began work between the Kenwood Ladies’ Bathing Pond and the Bird Sanctuary Pond on Monday.

They are set to drill 100 holes, ranging from three to 15 metres deep, over 10 weeks.

It is the first work to take place as part of the City of London Corporation’s £15million dams project, which has yet to receive planning permission.

Members of the Dam Nonsense campaign group, who oppose the project, last week accused the City of threatening wildlife by carrying out the ground investigations during bird nesting season.