5. The Department of the Environment may confirm, with or without modifications, or refuse to confirm, any byelaw submitted for confirmation, and subject to the proviso in paragraph 2 may fix the date on which the byelaw is to come into operation and subject as aforesaid if no date is fixed the byelaw shall come into operation at the expiration of one month from the date of its confirmation: Provided that, where the Department of the Environment proposes to confirm a byelaw with a modification which appears to it to be substantial, it shall inform the statutory harbour authority and require the harbour authority to take any steps it considers necessary for informing persons likely to be concerned with the modification and shall not confirm the byelaw until such period has elapsed as it thinks reasonable for consideration of, and comment upon, the proposed modification by the statutory harbour authority and by other persons who have been informed of the modification.