Surface Water Drainage

As of April 2015, all major planning applications have to demonstrate the use of sustainable drainage as part of their development. Northamptonshire County Council, as Lead Local Flood Authority, is now a statutory consultee on these planning applications. This page sets out how sustainable drainage should be delivered in Northamptonshire.

What are Sustainable Drainage Systems?

Sustainable drainage is a way of mimicking natural drainage in a built environment. Instead of surface water being piped underground, water remains at the surface, where it is cleaned and stored, reducing flood risk and improving the quality of the water before it either soaks into the ground or discharges to a watercourse.  This allows for greater biodiversity and amenity to be created.

SusDrain have developed a simple animated video overview of what Sustainable Drainage Systems (SuDS) are, which can be viewed to the right. Case studies of example SuDS schemes can be found on the SusDrain website.

Northamptonshire County Council (NCC) encourages all new development and redevelopment that requires planning permission to use SuDS in order to reduce flood risk, improve water quality and present options for biodiversity and public amenity. This is consistent with existing national guidance and local planning policy.

General SuDS Advice for Developers in Northamptonshire

The demands of each individual development will lead to a wide variety of solutions. Understanding Northamptonshire County Council’s priorities in terms of SuDS will help ensure the solutions are appropriate to our requirements.

It is important that developers establish the geological and hydrological conditions of their site at an early stage through ground investigations, before coming to any conclusions about the suitability of any particular SuDS system.

SuDS incorporate cost-effective techniques that are applicable to a wide range of schemes, from small developments to major residential, leisure, commercial or industrial operations with large areas of hard standing and roof. They can also be successfully retro-fitted into existing developments.

Local Standards and Guidance for Surface Water Drainage in Northamptonshire

We have published local guidance intended to assist developers in the design of all surface water drainage systems, and to support Local Planning Authorities in considering drainage proposals for new development in Northamptonshire. The guide sets out the standards that we apply in assessing all surface water drainage proposals. Please download the Local Standards and Guidance for Surface Water Drainage in Northamptonshire for more information.

Please note that this guidance is a ‘live’ document which will be continually updated and improved, therefore please ensure you are using the most recent version. The current version is: v1.3 August 2016 (Updated September 2017).

Flood Data and Information Requests

NCC can provide the following information to inform and supplement any flood risk/drainage assessment, regardless of the size or nature of the development:

  • A review of surface water drainage constraints from national mapping;
  • A review of site specific flood risk issues;
  • A summary of any historic flood incidents that have occurred on the site or within the related locality;
  • A review of flood related assets that are within the related locality;
  • A statement of any flood related issues you should consider further;
  • Advice on the type and nature of surface water drainage that could be designed into the relevant development; and
  • Information about flood risk consenting that may be required for your proposed development.

This service will provide a written email/letter response at a charge of £250 per site up to and including 5Ha in size. For sites greater than 5Ha in size, a charge of £750 would be applicable. These costs are exclusive of VAT and no VAT receipt will be provided. Please be aware this cost is to cover the time taken to investigate the area in question and to prepare a full response. Where no historic flooding information is available, or where there is no risk identified on the site, this charge will still apply.

Please complete the Flood Data and Information Request Form if you would like to use this service. We will then provide you with a unique reference number with which you will be able to make the required online payment. A full response to the data request will then be provided within 21 days of receipt of payment.

For more information about these data requests please contact the Surface Water Drainage Team at swdrainage@northamptonshire.gov.uk.

Technical Flood Advice Service

NCC can provide technical advice on the surface water drainage design and other local sources of flood risk, for any proposed development in the county.  We also advocate the use of pre-application discussions to ensure SuDS can be incorporated into developments at the early stage of design, and to streamline the planning approval process.

We may provide advice on documents and plans you provide, advice on aligning planning and consenting requirements, and other specific tasks we agree. Furthermore, we may carry out desk based analysis, arrange meetings and make site visits as set out in our agreement with you.

Following receipt of the completed Technical Flood Advice Request Form (see below), an officer will contact you to discuss the advice you want and prepare an agreement that is made up of an offer letter, a programme, and our standard terms and conditions. The programme will specify the tasks we will carry out, giving the approximate timetable and an order of cost for our advice.

We will use a rate of £84 per hour, for our planning advice agreements. These costs are exclusive of VAT and no VAT receipt will be provided.

Please complete the Technical Flood Advice Request Form if you would like to use this service. We will then provide you with a unique reference number with which you will be able to make the required online payment.

For more information about the technical flood advice service please contact the Surface Water Drainage Team at swdrainage@northamptonshire.gov.uk.

Planning Applications: What NCC would like to see

Detailed guidance relating to the information we would like to see in any Flood Risk Assessment or Drainage Strategy is provided in our Local Standards and Guidance for Surface Water Drainage in Northamptonshire.

The Local Planning Authority may have additional requirements for planning submissions so you should contact the relevant District or Borough Planning Authority prior to submitting an application.

Under the revised planning guidance, SuDS must be included in any new development unless demonstrated inappropriate. If a traditional (below-ground piped) drainage system is proposed over a sustainable drainage system, the onus is on the applicant to provide evidence to demonstrate that SuDS would be inappropriate for the development. If we are not satisfied with the evidence provided, we may object to the proposal.

Further information

The SusDrain website, an online community for sustainable drainage, contains a whole host of resources relating to the design and management of SuDS, alongside a range of case studies.