**5. Field studies**

The study area is Tirap Opencast Coal Mine, owned by North Eastern Coalfields (NEC) of Coal India Limited (CIL), located at the north-western end of the Makum Coalfield, Assam in India. The nearest township, Ledo, is about 3 km to the eastof Margherita. The headquarters of NEC is located at a distance of about 10 km. The national highway, NH38, forms the northern boundary of this colliery. The nearby

railheads for the coalfield are Margherita, Ledo, and Baragolai on a broad-gauge line of the North-East Railway.
