8.—(1) No part of the authorised development is to commence until for that part written details of the surface and foul water drainage system, reflecting the mitigation measures set out in the REAC including means of pollution control, have been submitted and approved in writing by the Secretary of State following consultation with the lead local flood authority on matters related to its function.
(2) The surface and foul water drainage system must be constructed in accordance with the approved details, unless otherwise agreed in writing by the Secretary of State following consultation with the lead local flood authority on matters related to its function, provided that the Secretary of State is satisfied that any amendments to the approved details would not give rise to any materially new or materially different environmental effects in comparison with those reported in the environmental statement.