​​​Sustainable drainage and planning requirements

Information about sustainable drainage in relation to planning permission.

As of April 2015, Local Lead Flooding Authorities (LLFAs) became statutory consultees for all major planning applications, to consider the effects of the development will not impact negatively on flood risk to the development and surrounding area.

The Government has introduced new policies and guidance for Sustainable Drainage for new development and you are advised to design drainage systems that are in accordance with national and local framework as detailed below, without which the LLFA would be unlikely to be able to support the granting of planning permission;

When to consult the Lead Local Flooding Authority (LLFA)

There may be occasions when consultations with the LLFA are required. Some of these occasions include:

  • In Flood Zone 1 for all major development with surface water drainage, consult your lead local flood authority. The LLFA will also be consulted for all development within Flood Zones 2 & 3;
  • A site-specific flood risk assessment should be provided for all development in Flood Zones 2 and 3. In Flood Zone 1, an assessment should accompany all proposals involving: sites of 1 hectare or more; land which has been identified by the Environment Agency as having critical drainage problems; land identified in a strategic flood risk assessment as being at increased flood risk in future; or land that may be subject to other sources of flooding, where its development would introduce a more vulnerable use;
  • This includes householder development, small non-residential extensions (with a footprint of less than 250m2) and changes of use; except for changes of use to a caravan, camping or chalet site, or to a mobile home or park home site, where the sequential and exception tests should be applied as appropriate.

In order to assist in the assessment of planning applications the LLFA would require the information detailed below to accompany any major planning application.

The Tees Valley Technical Guidance Documents Vol 1 & 2 will assist you with the local standards along with other requirements when designing your developments drainage.

Detailed Desktop Study

  • Topographic Survey of the development site;
  • Existing surface water flow routes/ drainage infrastructure and identify any watercourses;
  • Flood risk from rivers/surface water and/or groundwater;
  • Geological and soil types generic to the area.

Flood Risk Assessment (FRA)

  • An appropriate site-specific FRA where specified as a requirement by the Environment Agency (EA) click here to see criteria;
  • Evidence of discussions/agreements with Northumbrian Water.

Drainage Strategy

  • Sustainable drainage proposals (SuDS Hierarchy);
  • Outfall locations;
  • Discharge rates;
  • Storage requirements and supporting calculations;
  • Maintenance Strategy/Plan;
  • Ground investigations (dependant on type of drainage proposal).

The above should be accompanied by:

  • Detailed Drainage Drawings including; Details of inlets, outlets and flow control specifications. Long and Cross Sections of the proposed drainage system should also be provided;
  • Flow paths for the storm events 1 in 1yr, 1 in 2yr, 1 in 30yr and 1 in 100yr + Climate Change (as specified in Tees Valley Technical Guidance – Vol 2);
  • Storm simulation results/reports (e.g. MicroDrainage).

Tees Valley SuDS Guidance and Design Guide

The Tees Valley SuDS Guidance and Design Guide is available to download and view below and provides information regarding reducing damage from flooding, improving water quality, protecting and improving the environment, protecting health and safety and ensuring stability and durability during drainage.

The LLFA is happy to provide pre-application advice free of charge, should you wish to discuss further please contact Lyndsey.hall@redcar-cleveland.gov.uk or telephone on 01287 612343.​