10. If before the expiration of 28 days from the date of the first publication of the notice under paragraph 7 or of 25 days from the publication of the said notice in the Belfast Gazette an objection is received by the Department of the Environment from any person on whom a notice is required to be served under paragraph 8, or from any other person appearing to that Department to be affected by the application, and the objection is not withdrawn, that Department before giving that authorisation, may cause an inquiry to be held by the Water Appeals Commission for Northern Ireland and where that Department causes such an inquiry to be held, the power under Article 8(4) of the [1973 NI 2] Water and Sewerage Services (Northern Ireland) Order 1973 to substitute a new decision or vary the decision of the Water Appeals Commission may be exercised by that Department.