Pre-Application & Outline Planning Drainage Strategy

What is needed to support an Outline Planning Application?

Outline Planning is focused on the concept and principles of drainage. Due to it being more conceptual, it leads to conditions or more information being requested as planning consent is issued which doesn’t provide permission to start work.

The four questions below simplify what questions need 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, and 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?

Your outline planning report will answer these questions with drainage calculations and a plan demonstrating the potential future arrangement.

It may not be as detailed as full planning or pre-construction, but it still has to be implementable and detailed enough to justify the selection and specific sizing of SuDS devices and products—including the tank size, pond size, green roof usage, etc.

Pre-application and outline planning projects 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.

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 about its progress to identify what is feasible and ensure that the solutions provided are achievable in terms of site design, cost, and sustainability. We welcome the opportunity to discuss your project.