25. Any element of the authorised development which directly affects any floodplain must not be commenced until a floodplain compensation scheme has been submitted to and approved in writing by the relevant planning authority. Except for the floodplain compensation scheme itself no above ground part of the authorised development in any floodplain may be commenced until the relevant compensation scheme has been implemented in full. The scheme shall be fully implemented and subsequently maintained in accordance with the timing and phasing arrangements embodied within the scheme or within any other period as may subsequently be agreed in writing by the relevant planning authority.