Why in News?
Recently, several workers have been trapped for more than 12 hours in a rat-hole mine after it was flooded with water in Dima Hasao district, Assam.
| Types of Rat-Hole mining | |
| Side cutting | Box cutting | 
| Narrow tunnels are dug on the hill slopes and workers go inside until they find the coal seam. | A rectangular opening is made. 
 | 
| Size – Very thin, less than 2 m in most cases. | Size – Varying from 10-100 sqm and through that a vertical pit is dug, 100-400 feet deep. | 
The two rivers, Lukha and Myntdu, became too acidic to sustain aquatic life because of unregulated mining in Meghalaya.

Reference
The Indian Express| Rat Hole Mining trapped workers in Assam
Related News Article