PPS 15 Planning and Flood Risk (Revised)·Page 38·6.32
Working Strip Requirements for Flood Defence and Watercourse Development
Development beside flood defences, control structures, or watercourses must retain an adjacent working strip of minimum 5 metres width (up to 10 metres where necessary) with clear access and egress for maintenance by Rivers Agency or other statutory undertakers.
Where a new development proposal is located beside a flood defence, control structure or watercourse it is essential that an adjacent working strip is retained to facilitate future maintenance by Rivers Agency, other statutory undertaker or the riparian landowners. The working strip should have a minimum width of 5 metres, but up to 10 metres where considered necessary, and be provided with clear access and egress at all times. The retention of a working strip along watercourses will have added benefits, including general amenity, enhanced biodiversity and increased control over water pollution, the latter assisting in the implementation of the Water Framework Directive.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/PPS 15 - Planning and Flood Risk (Revised).pdf