Full Planning Drainage Strategy

A full planning surface water drainage strategy is a highly detailed review of your site. It requires multiple datasets and site surveys to inform the decision-making process of how best to mitigate the runoff of water post-development.

​National Policy in England now requires that all developments should consider the mitigation of surface water from their site and use SuDS where possible.

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Do I need a Surface Water Drainage Strategy for Full Planning?

If you’re proposing a development in the UK that includes constructing a new building or reducing the amount of ‘green’ areas on your site than you’ll likely require a full planning surface water drainage strategy (SWDS). National Policy also states that all developments need to consider how surface water is mitigated on their site and make use of SuDS where possible.

Without a surface water drainage strategy, your planning application could be rejected. You’ll then need to resubmit, costing time and money, or have a retrospective planning application enforced.

A surface water drainage strategy in it simplest form assess the amount of rainfall that could fall on a site while assessing the type of surfaces that will be there, therefore analysing the impacts the runoff rate will have on the site and surrounding area. It then provides mitigation measures (such as SuDS products) to store or move this water elsewhere to prevent flooding.

SuDS (Sustainable Drainage Systems), are devices or products that mimic the natural water mitigation measures, such as ponds or soakaways. All major applications should be accompanied by a site-specific drainage strategy that demonstrates a use of SuDS unless you can show it’s impractical or inappropriate to your site.

A surface water drainage strategy is not just restricted to major developments. It can also apply to minor developments, like house extensions.

Need a Surface Water Drainage Strategy? Our team are ready to support you.

Drainage Planning Experts

Nick Darling-Drewett
Principal Flood Risk Consultant
I’m a Principal Flood Risk Consultant at Aegaea with extensive experience in producing FRAs and drainage strategies. Specialist Subject: FRAs
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Douglas Swinbanks
Principal Flood Risk Engineer and Hydrologist
I’m a Principal Flood Risk Engineer and Hydrologist based in Edinburgh. Specialist Subject: Scotland Policy and Integrated Catchment Modelling.
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Oliver Harvey
Senior Flood Risk Consultant
I am a Senior Flood Risk Consultant at Aegaea with extensive experience in supporting developers and clients by providing flood risk and SuDS reports to ensure they achieve their aspirations for...
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What's needed to support a full planning drainage application?

Full Planning is a detailed assessment and plan for your site. It requires multiple pieces of data to inform the decision-making process of how best to mitigate the runoff of water post development.

With multiple pieces of data to review, each project must be viewed individually; no application is the same. A Surface Water Drainage Strategy is unique, especially the approach and methods applied to each development.

Each assessment is different due to multiple factors driven by the findings of the data, which can include;

  • Environmental conditions – topography, soil type etc,

  • Flood zone,

  • Type of development,

  • Location in the country,

  • Greenfield or brownfield,

  • Ability to discharge water off site,

  • Planning policies etc….

All of these need to be considered, cross referenced, and assessed in order to provide a robust report that supports the future development of the site and remains fully compliant with national guidelines and policy.

There are four key questions listed below, which simplify what needs to be answered to support a planning application.

  1. What is being proposed and how will it impact the runoff of surface water post construction?

  2. How will the increase in surface water runoff be mitigated post development? What SuDS could be used?

  3. Where could the sustainable urban drainage systems (SuDS) be located on the site? and;

  4. How will the runoff be discharged from the site and at what rate (litres per second)?

A Planning Authority require these answers to be provided in the form of a report, with surface water drainage calculations and a detailed, scaled plan demonstrating the potential future arrangement. This will include pipe diameter, pipe length, type of connections, invert levels, manhole covers, and levels etc.

Full planning applications we have supported

  • Minor Development – extensions to residential and commercial properties

  • Major Development – Commercial / Residential / Industrial / Energy / EIA

  • Residential Development 1 dwelling through to 500+

  • Solar Farms and Battery Storage facilities

  • Agricultural buildings – barns, stables , silos

  • Leisure and recreational facilities – hotels, adventure golf, stadiums, leisure centres

  • Schools and more….

Need a Surface Water Drainage Strategy? Our team are ready to support you.

How we can support your planning application

As part of our work, we have simplified what can be viewed as a complex planning document into the 7 steps below;

The SuDS process.

  1. Assess Site location and Data Review.
  2. Policy Requirements (National/Regional/Local)
  3. Undertake scientific engineering calculations of the existing Site against the Proposed Development
  4. Review the findings of the calculations against site conditions (site analysis/data review) to assess what SuDs could be adopted to mitigate surface water at the Site
  5. Outline the SuDS in an order (SuDs train) that provides as many benefits as possible (Water quantity, Water quality, Amenity, Biodiversity)
  6. Identify a point of discharge against the SuDS hierarchy and define the rate, litres per second l/s
  7. Production of a drainage layout drawing to scale and supporting report.

As the project evolves we regularly communicate with our clients on how the project is progressing to identify what is feasible. We’ll make sure that the solutions provided are achievable in terms of site design, cost, and sustainability. We welcome the opportunity to discuss your project, no matter the size or complexity.

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Aegaea work alongside home owners, private developers, planning consultants, architects, local authorities, international development agencies and contractors. Aegaea know exactly how to help you.

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