Sustainable Drainage Systems Design Guidance

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

Combined sewer and pumping

Combined Sewer

The discharge of surface water to a combined sewer should be considered as a last resort. Foul and surface water flows within the site should remain separate prior to the final manhole leaving the site.

Confirmation from the sewerage undertaker should be provided to show that capacity is available within the existing system to receive flows from the site. This should be a developer enquiry application or similar.

Pumping

The pumping of surface water should only be used as a last resort. If the pumping of surface water is proposed, clear evidence and justification should be provided. A plan showing relevant above and below ground levels which clearly illustrates the need for a pumped connection should be submitted.

The maintenance and management plan should clearly set out measures proposed to reduce the likelihood of and mitigate for pump failure. Exceedance routes in the event of pump failure should be presented and should not increase flood risk to properties or key infrastructure.