24. Prior to the commencement of any element of the authorised development which directly affects a watercourse or floodplain, a construction working method statement for such element to cover all works in, over under or within 8 metres of the top of the bank of either watercourse or their floodplains must be submitted to and agreed in writing by the relevant planning authority. Thereafter the development must be carried out in accordance with the approved scheme and any subsequent amendments agreed in writing with the relevant planning authority.