Section 4(6)(b) in The Environment (Protection) Rules, 1986
(b)where the person to be served is an officer serving Government, if the document is addressed to the person and a copy thereof is endorsed to the Head of the Department and also to the Secretary to the Government, as the case may be, incharge of the Department in which for the time being the business relating to the Department in which the officer is employed is transacted and is either,-(i)sent by registered post, or(ii)is given or tendered to him;