- Navy officers search possible only when all water has been drained
- Currently the water is 250 feet deep in the vertical tunnel
- The divers have requested for halogen bulbs for better visibility
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A joint team of the navy and the National Disaster Response Force started work on Monday morning. The illegal rat-hole mine had collapsed on December 13 after water from an adjacent abandoned mine and a nearby river flooded it.
"Rat hole" mining involves digging vertical pits into the side of hills and then burrowing horizontal tunnels to reach the lateral coal seams. The tunnels are not more than 5 feet in height.
Currently the water is 250 feet deep in the vertical tunnel. At least two horizontal tunnels are expected to be lying below the water, where the men could be trapped.
On Monday, the navy tested its remotely-operated vehicle, lowering it underwater. The vehicle can be used to examine the vertical tunnels. The vehicle would also show if divers can safely get inside the tunnels.
The divers have requested for more halogen bulbs inside the shaft for better visibility. There are also concerns over decompression sickness - damage to body tissues when divers go too deep and cannot decompress properly once they get back to surface.
Coal India Ltd's pumps have also reached the site, but are yet to be used due to logistical issues, sources said.
The rescue operations were suspended on December 16 following flash floods from a nearby river.
A team of about 100 experts from the National Disaster Response Force or NDRF have been camping at the site, but their operations have been hampered by lack of sophisticated equipment.
Mining was banned in mineral-rich Meghalaya in 2014 after people said it was polluting water bodies. But the practice continues with locals illegally extracting coal using dangerous "rat-hole" mines, which means digging into the side of hills and then burrowing horizontal tunnels to reach a coal seam.
There are an estimated 5,000 rat hole mines in the state, mostly in East Jaintia Hills. Migrant labourers say there has been a 70 per cent economic slowdown since the ban. They want the ban to be lifted.