New Delhi: Vertical drilling from the top of the Uttarakhand tunnel where 41 construction workers are trapped has reached between 30 and 32 metres down the way, a government official said on Monday (November 27) afternoon.Speaking for the National Disaster Management Authority, Lt Gen (Retd) Syed Ata Hasnain said that efforts to vertically drill another, narrower pipeline between six and eight inches wide from the tunnel’s top had progressed to 75 metres down the way.This narrower pipeline would help gauge the kind of soil and rocks that the Sutlej Jal Vidyut Nigam would encounter while carrying out the primary, wider vertical drilling, Hasnain explained.The estimated depth of drilling needed to get to the workers is 86 metres, he added.He also said that horizontal drilling from that end of the tunnel closer to the workers will commence on Monday evening by army engineers and ‘rat miners’ in teams of two.VIDEO | Uttarkashi tunnel rescue UPDATE: “The broken blades of the auger machine have been fully retrieved. There were some obstacles while retrieving the broken part, but the damage has been fixed. Now, the manual technique will be employed by tonight with the help of Indian… pic.twitter.com/UCtDORw0YG— Press Trust of India (@PTI_News) November 27, 2023According to Reuters, ‘rat mining’ is a “primitive, hazardous and controversial method used in India mostly to remove coal deposits through narrow passages”.The ‘rat miners’ were brought to the tunnel after the main horizontal drilling (or auger) machine used to reach the trapped workers irreparably broke down on Friday (November 24).News reports cited officials as saying as of Monday night that the ‘rat mining’ had begun.Twelve metres of debris still lies between the workers and rescue personnel as of Monday night, the Indian Express reported.A landslide near the tunnel on November 12 caused it to collapse, trapping 41 construction workers behind debris at a distance of 260 metres away from one of its entrances at Uttarakhand’s Silkyara town.The trapped workers were initially provided with oxygen, water and dry food, but piping developments last week allowed rescue personnel to supply the workers with hot meals.An endoscopic camera was also inserted through a pipe to relay visuals of the trapped workers.Efforts are also on to begin vertical drilling towards the tunnel’s far end at Barkot, as well as to drill perpendicularly from the main site of the horizontal drilling at Silkyara, a press release by the Union roads ministry said on Monday.Officials have not provided a timeline for when the trapped workers may be rescued, saying instead that the focus is on getting them out safely.‘No involvement in tunnel’s construction’: AdaniThe Adani Group said on Monday that it was not involved in any way in the tunnel’s construction.“We clarify with utmost emphasis that the Adani group or any of its subsidiaries has no direct or indirect involvement of any kind in the tunnel’s construction,” a spokesperson for the conglomerate said according to PTI.They added: “We also clarify that we do not own or hold any shares in the company involved in the tunnel’s construction.“At this time, our thoughts and prayers are with the trapped workers and their families.”