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Sustainable Drainage Systems

We’ve compiled guidance, Local Authority Requirements, FAQs, useful Downloads, Videos and Case Studies. We also organise Continuous Professional Development training events.

What are Sustainable Drainage Systems?

Sustainable Drainage Systems (SuDS) are becoming an integral part of new development planning submissions, driven by Local Authority Water and Flood Management Plans.

SuDS manage peak runoff after a rainfall event to prevent flooding. They try to mimic what would happen if there was no development on site. They can be designed to convey surface water and slow runoff down (attenuate) before it enters watercourses.

Surface water should infiltrate into the soil directly but this may not always be possible as a single solution. This can be due to different soil and rock types, groundwater levels and slope profile.

How does this affect my client?

Local Authorities are now looking for the inclusion of SuDS into new developments. They must now be applied to all major schemes of 10 units or more.

In many instances now, Architects and planning consultants need to demonstrate why a SuDs is not appropriate for the site. If they can’t, then they need to consider how an appropriate SuDS will be integrated to the development so that it does not increase flood risk on site or elsewhere.

Understanding Local Authority Requirements

Planning conditions on SuDS vary considerably across the country. It is crucial that Architects and planning consultants understand these differences, assess the site and design a SuDS scheme that meets planning requirements on behalf of their client.

We have developed a unique catalogue of planning authority SuDS requirements.

Choose your region

Get an Expert View on SuDS

We have many years experience in assessing site drainage and designing suitable SuDS systems as part of Master planning and pre-application submissions.

We have a proven track record of delivering successful schemes through our technical expertise. Our drainage reports provide:

  • an initial view on site infiltration capability for surface water drainage
    more detailed run off calculations
  • Preliminary SuDS design that can be used as part of the pre-planning engagement process
  • We also run a regular series of webinars and can provide in-house seminars

FAQs

Who are SuDS reports are intended for?
  • House builders and developers
  • Property professionals such as architects, planning consultants, and land agents
  • Private individuals
  • Businesses
  • Insurance brokers and lenders
Why is a SuDS Report required?
  • Validating planning applications at Pre-Planning Stage
  • Planning Conditions
  • Building and flood mitigation design
  • Due diligence
  • Code for Sustainable Homes
  • SuDS approval boards (SABs)
  • Lending, mortgages, and pension funds
How do I know what Level of SuDS Report I need?

For initial screening at the conceptual design stage a SuDSmart or SuDSmart Plus Reports typically support developers and regulators with infiltration drainage advice. This is the preferred method for managing surface water without increasing flood risk downstream.

When infiltration drainage cannot be undertaken at a site due to the underlying ground conditions, other more conventional drainage systems are introduced in our SuDSmart Pro Report (Note: infiltration drainage techniques are also considered when possible).

What does a SuDSmart Pro Report contain?

SuDSmart Pro Reports analyse the potential run-off from a site so that it can be managed effectively to ensure there is no increase in flood risk on or off the site. Post development run-off rates are assessed for a range of storm events including an allowance for future climate change.

A drainage strategy is developed to offset the increase in surface water run-off from the new development using the principles of SuDS and the code for sustainable homes. The hydrological context of the site is assessed, along with any potential issues that may affect the SuDS system.

A range of potential options are assessed including discharge to the ground, surface water courses or sewerage. The report provides sizes and flow rates for a range of sustainable drainage options that may be considered.

Will my report satisfy the Local Planning Office or LLFA?

SuDSmart Reports can be used to support a planning application at Pre-Planning Stage, or alternatively address a Planning Condition prior to planning being granted.

SuDSmart and SuDSmart Plus Reports provide a cursory look at infiltration SuDS which is the preferred method for managing surface water. Whether infiltration techniques are feasible or not will determine the suitability of other SuDS schemes going forward. The level of detail required depends on the specific requirements of your local authority.

You should note that our most detailed report, SuDSmart Pro provides alternative options and preliminary scheme layouts that should be subject to more detailed review at the master planning stage.

In our experience, this level of detail is required for more stringent planning authorities or for more complex sites that warrant more detailed assessment.

How do I know what to do next?

All SuDSmart reports include recommendations for next steps. We will always advise on the most cost effective way to move forward and provide details of how to do this whilst meeting in the needs of the planning department.

What if the Local Authority or LLFA request further information to support my application?

GeoSmart are able to provide access to a range of highly experienced senior consultants, suppliers and engineers, who can provide a more detailed review of your site specifics and planning requirements.

Please contact a member of the GeoSmart team to put you in touch when further detailed assessment is required.

What is GeoSmart’s SuDS Infiltration Map (SD50)?

The GeoSmart SD50 map provides an assessment of the capacity of the ground to receive infiltration depending on the nature, thickness and permeability of the underlying material and the depth to the high groundwater table.

  • Allows preliminary assessment of the site without the need for bespoke SuDS design.
  • Use in conjunction with the SuDSmart report range to identify SuDS infiltration suitability and flow/volume design data.
  • Combination may be sufficient to obtain outline planning.
  • Provides customers with clear site risk profile on drainage cost and land area needed.

To discuss the SD50 SuDS screening map and how it can improve your planning submission for your client, contact us today.

See what our customers have to say...

"During the conveyancing process for my current house purchase, I was extremely concerned to find the general search results revealed the house was at 'moderate risk of groundwater flooding'. I was unable to get any further information from anyone until I contacted GeoSmart. The staff I spoke to were friendly, helpful, efficient and extremely knowledgeable. The information provided was very site specific and focused. The staff member who talked me through the information and maps provided was very knowledgeable, answered all my questions and allowed me plenty of time to discuss issues. Thanks to GeoSmart for their great service."
Linda Barton
"We were impressed by the speedy, well-informed service and personal contact that we received. The report was thorough and comprehensive. We will certainly use GeoSmart's services in the future"
Gregory Gray
Gregory Gray Associates
"I would like to say that dealing with GeoSmart was a seamless experience from beginning to end - thank you for that"
Martin Lloyd
Martin Lloyd Associates
"Everyone involved from initial approach to receipt of report was knowledgeable, efficient and focused"
Robert McCall
OeMO Ltd
"Great service! Extremely fast and the report was very detailed and well received by the planners. Many thanks GeoSmart, we will definitely use your services again"
Nigel Slack
Michael Eyres Partnership LLP
"The service was great, fast and efficient. Everyone we talked to was very helpful and the details were well received by the planners"
Ben Thorns
Solid Digital Marketing Ltd
"The service for a Phase 1 Contaminated Land Study was excellent, fast and efficient! GeoSmart were willing to assist despite the extremely tight timescale to work with. We will definitely consider using your services again"
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Hunter Page
"Efficient and friendly service, GeoSmart provided a clear and concise report within the timescales advised. Great service and I would have no problem recommending"
Geraint Harris
Vitec Consult
"We are very pleased with the service provided by GeoSmart. Their reports have been used to assist with numerous planning applications and have always been delivered to budget and on-time, much to our clients’ appreciation. We look forward to working with GeoSmart on future projects"
Alan Gunne-Jones
Planning & Development Associates
"The service provided was efficient and friendly. From the first phone call to GeoSmart they provided a clear, professional approach to my request within the timescales advised. Great service and I would have no problem recommending"
John Childs
Private Developer
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