SuDS requirements for new developments

As Lead Local Flood Authority, we act is a statutory consultee for major planning applications. We also review proposals for smaller developments. We check proposals to ensure that surface water drainage and local flooding issues are taken in to account by developers using appropriate SuDS techniques. This means that not only should a site not be at risk of flooding, but that flood risk in other places does not increase as a result of any development proposals.

We recognise that, through historic drainage practices and climate change, a general increase in flood risk has resulted. The proper consideration of surface water as part of all development, and the use of Sustainable Drainage Systems (SuDS), is key to the successful management of both existing and future flood risk.

For the greatest effect, flood risk must be considered at all stages of the development process. Robust design standards must be adhered to, and an allowance for climate change made. Both the volume and routes of exceedance flows, originating from within and outside a development site, must be assessed. Provision for the appropriate maintenance of any drainage systems must also be made.

By using the policies and documents below, you can ensure the correct level of detail is submitted with your planning application to help us properly assess the proposed sustainable drainage and methods to manage flood risk.

Sustainable Drainage Systems (SuDS) Policies

In December 2014, DCLG set out the changes to the planning system that will help to increase the use of the sustainable drainage systems. As a result, amendments were made to the Planning Practice Guidance which accompanies the National Planning Policy Framework. DCLG’s statement sets out how SuDS should be delivered as part of all major development and is accompanied by the Non-statutory technical standards for the design, maintenance and operation of sustainable drainage systems to drain surface water.

Our policies further clarify the requirements for SuDS on all new development:

Shropshire Local Development Framework: Adopted Core Strategy. Policy CS18: Sustainable Water Management
Site Allocations and Management of Development (SAMDev) Plan. Policy MD2: Sustainable Design
Local Flood Risk Management Strategy. Policy 4: the Role of the Lead Local Flood Authority in the Consideration of Proposals for Sustainable Development
SuDS Handbook. This is currently being prepared and is expected shortly. Surface Water Management: Interim Guidance for Developers should be used in the interim

All of the above documents can be found in the related documents section on this page.

Surface Water Management: Interim Guidance for Developers

This document outlines the requirements for the management of surface water for all planning applications made to Shropshire Council. It is used by council officers and members in considering the appropriateness of planning applications in relation to flood risk, as well as being available for the general public to use in formulating responses to planning applications. This document will be replaced shortly by the SuDS Handbook.

‘Urban Creep’ and its effect on Surface Water Discharge Rates

Urban creep is the conversion of permeable surfaces to impermeable over time e.g. surfacing of front gardens to provide additional parking spaces, extensions to existing buildings, creation of large patio areas. Much research has been carried out in to the effect of urban creep and its effect on the drainage systems which cater for urban areas. It has been shown that, over the lifetime of a development, urban creep can increase impermeable areas by as much as 10%.

Whilst we have always considered the impermeable areas proposed on new development sites and accounted for climate change we have not, previously, accounted for urban creep. From 1 February 2015 an allowance for urban creep will now be required as part of the surface water drainage proposals for new development in Shropshire. The requirement is shown below.

The consideration of urban creep should be assessed on a site by site basis but is limited to residential development only.

The appropriate allowance for urban creep must be included in the design of the drainage system over the lifetime of the proposed development. The allowances set out below must be applied to the impermeable area within the property curtilage:

Residential development density, Dwellings per hectare	Change allowance % of impermeable area
≤ 25	10
30	8
35	6
45	4
≥ 50	2
Flats & apartments	0

Note: where the inclusion of the appropriate allowance would increase the total impermeable area to greater than 100%, 100% should be used as the maximum. “Curtilage” means area of land around a building or group of buildings which is for the private use of the occupants of the buildings.

Making an application

When you make a planning application we require you to submit a Surface Water Management Document in the form of Appendix C or Appendix D from the Interim Guidance for Developers (downloadable from the related documents section of this page).

This is required for;

All new build residential, commercial and agricultural developments;
Commercial extensions;
Conversion of agricultural buildings e.g. barn conversions, or;
Any other proposals that may have an affect on surface water drainage or flood risk.

This helps ensure you provide the relevant information so we can approve your application in a timely fashion. If we have any more questions regarding your application we will contact you.

You may also need to submit a Flood Risk Assessment (FRA), in accordance with the National Planning Policy Framework (NPPF), depending on the size and location of your proposed development.

To help you decide which documentation you need to supply with your application, please look at our flow chart.

Further information

Further information is available to download:

For more information about Sustainable Drainage take a look at the Ciria SuDS Manual.