Surface water management for new developments

Our role in managing flood risk includes making sure that new developments in Cheshire East have sustainable surface water drainage systems.

Sustainable drainage systems control surface water run-off close to where it falls and copy natural drainage as closely as possible. This helps:

  • reduce the risk of flooding
  • reduce the harm caused by any floods that do happen
  • remove pollutants at source
  • give opportunities to combine water management with green space for the benefit of people and wildlife

Surface water management - all planning applications

Sustainable surface water management is a material consideration for all planning applications. This means all development proposals must include a a site-specific surface water drainage strategy following sustainable urban drainage guidelines (SuDS).

For detailed guidance on SuDS, see the   CIRIA SuDS manual.

On greenfield sites, surface water run off must be managed to achieve at least no increase in run off rates. Where possible, there should be a reduction in rates.

On previously-developed sites, run off proposals should demonstrate a reduction in rates in line with the non-Statutory Technical Standards for Sustainable Drainage Systems (2015) (or any later replacement standards).

In line with Part H of the building regulations, surface water drainage options must be considered in the following order. An option higher in the hierarchy can only be agreed if it can be demonstrated that earlier options are not feasible.

  1. Into the ground (infiltration) - for good practice guidance, see  Soakaway design
  2. To a surface water body
  3. To a surface water sewer
  4. To a combined sewer

Development proposals for critical drainage areas must address and mitigate known risks in the area. A critical drainage area is an area within flood zone 1 which has critical drainage problems and has been notified to the local planning authority by the Environment Agency.

Where surface water management plans require a connection to drains or sewers in the highway, our consent is needed as well as consent from the owner of the drain or sewer pipes. 

Development in a critical drainage area should not result in the loss of open watercourses. Culverts should be opened where possible. We will only permit the culverting of existing watercourses if there is an overriding need.

Proposals must show how watercourses and riverside habitats will be conserved and enhanced.

Surface water management - major planning applications

As Lead Local Flood Authority, we are a statutory consultee for surface water drainage on all major planning applications. To approve an application, we need to be satisfied that:

  • the proposals are appropriate in relation to flood risk and pollution control
  • there are clear arrangements in place for ongoing maintenance 

A development counts as major if it involves one or more of the following: 

  • mineral extraction
  • waste development
  • more than 10 houses
  • houses on a plot with an area of 0.5 hectares or more, if the number of houses isn't known
  • floor space of a thousand square meters or more
  • a site of 1 hectare or more