(2) Where service could not be effected by the means referred to in subsection (1), the service shall be effected by affixing a copy of the notice – (a) at the facility which is the subject matter of the notice; (b) where a contravention is being committed, or has been committed, or is suspected to have been committed. (3) A certificate of an authorised officer or any other officer of the Ministry as to service under subsection (1) shall be prima facie evidence of effective service of the notice on the person affected. 15. Revocation of notices Where he is satisfied that – (a)(i) the measures required to be taken in a notice have been implemented; and (ii) there exists no further risk to the environment or to human or animal health caused by the activity or the manner in which the activity is carried on; or (b) the notice is not, or will not be effectual, the Permanent secretary may revoke a notice and shall inform the person affected in writing. 16. Appeals (1) Any person who feels aggrieved by a decision taken by the Permanent Secretary may, within 21 days of the communication of the decision to him, and on payment of the prescribed fee, appeal against the decision to