Uttarkashi (Uttarakhand) [India]: The GPR (Ground Penetrating Radar) survey team was sent back to Delhi as manual drilling began on the 16th day of the rescue operations in Uttarkashi.
The Ground Penetrating survey will not be conducted inside the rescue tunnel again, said officials.
The Ground Penetrating team who came to conduct a survey at the rescue site of the Silkyara tunnel, informed that there were no heavy objects up to 5 metres in the rescue tunnel on Friday.
The rescue work was halted as the Auger machine broke as soon as it got struck with a heavy object. The team, which came from Parsan Overseas Pvt Ltd Delhi, used the ground-penetrating radar (GPR) technique to examine the rescue tunnel.
Ground Penetrating Radar, also known as GPR, Georadar, Subsurface Interface Radar, or Geo-Probing Radar, is a totally non-destructive technique to produce a cross-section profile of the subsurface without any drilling, trenching or ground disturbances.
GPR profiles are used for evaluating the location and depth of buried objects and to investigate the presence and continuity of natural subsurface conditions and features.
Meanwhile, in the latest update, Micro tunnelling expert Chris Cooper informed that all the Debris of the auger machine has been removed and manual drilling to reach the trapped labourers will start in a few hours.
“All the debris (of the Auger machine) removed. (Manual drilling) will probably start after 3 hours,” Chris Cooper told media today.
A rat hole mining technique will be employed to remove the debris inside the pipe. As per the official sources, a team of 6 specialists have reached the site to undertake the manual drilling work. They will go inside the 800-mm pipe of the tunnel to remove the debris manually.
Detailing the process, a specialist about to carry out the rat mining process said that “A Shovel and other specialist tools will be used in the process. For oxygen, we will take along a blower with us”.
Even as the manual drilling process begins a simultaneous vertical drilling process from the top of the mountain also continues. As per officials, over 35 metres of vertical drilling work have been completed so far out of the 86 metres needed to reach the trapped workers.
