Sustainable Drainage Systems Major Design Guidance

This advice sets out the requirements that the LLFA has for drainage strategies and surface water management provisions associated with applications for major development.

Evidence required

Within their drainage strategy, the applicant should clearly set out how they are compliant with each of the National Standards for Sustainable Drainage Systems. It is recommended that each standard is addressed separately.

Non-technical summaries should also be provided, in line with subsection 3.25 of the National Standards for Sustainable Drainage Systems.

The LLFA would expect that CIRIA’s SuDS Strategy template for major developments is submitted alongside the drainage strategy. Please note that in line with the general requirements of standard 3, if the proposed site is in an area where local evidence supports an approach to managing surface water runoff from developments that is more stringent that this standard, (i.e. a discharge rate of less than 3 l/s/ha) the local approach shall take precedence.