Section 108(3) in The Coal Mines Regulations, 2011
(3)In coal, the sides shall either be kept sloped at an angle of safety not exceeding 45 degree from the horizontal, or the sides shall be kept benched and the height of any bench shall not exceed three metres and the width thereof shall not be less than the height:Provided that the Regional Inspector may, by an order in writing and subject to such conditions as he may specify therein, exempt from the operations of this sub-regulation any working, in the case of which special difficulties exist which in his opinion make compliance with the provisions thereof not reasonably practicable.
