Designed to control water flow and the distribution of polluted water in developed, urban areas, SuDS work by enabling water to soak into the ground (infiltration systems), slowing down the flow of water into watercourses (retention systems), storing and transferring water from vegetation into the atmosphere (evapotranspiration) and removing pollutants from water (filtration).
Faced with a future of climate uncertainty, SuDS are a far more competent water drainer, container and manager than their traditional counterparts like underground pipe systems, borehole soakaways and drainage bricks.
Sustainable drainage solutions come in several forms, each of which have different purposes and suit a specific type of landscape.
Variations of surface water drainage solutions examples include:
SuDS provide many advantages to people, society, wildlife and the environment alike due to their variety.
Whilst the positives of sustainable drainage systems far outweigh the negatives, there are a couple of downsides to SuDS.
Firstly, the room for further urban development can be difficult where sustainable drainage systems have been integrated as green spaces.
Wetlands and marshland offer a wealth of biodiversity as well as managing water efficiently so being granted permission to build on such areas would be difficult.
Another downside to SuDS outlined by the British Geological Survey (BGS) is the requirement of permeable matter beneath the ground for infiltration drainage systems to function correctly.
According to the BGS, the areas where these types of SuDS are limited to places where gravels, sands and other free-draining mediums are present.
If surface water is unable to soak through the ground, it will cause flooding or could transfer pollutants into local watercourses.
There are several ways that developers and architects profit from sustainable drainage systems.
Firstly, from a financial perspective, the construction and maintenance of SuDS has been proven to be a cheaper alternative to traditional drainage systems.
In addition, SuDS can improve the financial value of land and property with the integration of green, natural spaces which combat flooding and pollution in a more attractive way.
Developments constructed in an area with sustainable drainage systems will also improve their aesthetic value and offer wellbeing benefits to potential occupants.
Furthermore, the presence of SuDS will reduce the time taken for planning permission to be granted, especially in instances where SuDS schemes are key to drainage strategies of local planning authorities.
Most local authorities will require a SUDS report to be undertaken before any construction can take place, even in areas with a relatively low flood risk.
If SuDS are to be incorporated into the layout of your development, you will need to submit plans for them, usually in the form of a sustainable drainage strategy, to your local planning authority.
According to part C of paragraph 167 in the National Planning Policy Framework, local planning authorities should only permit developments if the area “incorporates sustainable drainage systems, unless there is clear evidence that this would be inappropriate.”
In paragraph 169, the policy additionally states that major developments need to incorporate SuDS unless it would be inappropriate to do so. The policy outlines that the SuDS should:
Under the ‘Distinctive & Natural’ chapter of Planning Policy Wales, it is stressed that the Welsh planning system should ensure that SuDS are an “integral part” of a new development’s design, and should be “considered at the earliest possible stage when formulating proposals for new development.”
In cases where new developments of more than one dwelling are planned for construction, or in instances where the area that will be covered by the development equals or exceeds 100 square metres, approval is required from the SuDS Approval Body (SAB) prior to any construction.
The SAB approval will also require developers to demonstrate:
Moreover, in cases where infiltration SuDS are not suitable, the policy states that “consultation with drainage bodies and NRW should be undertaken and relevant evidence and information drawn from Area Statements taken into account.”
The Scottish Planning Policy states that the planning system should promote avoidance of increased surface water flooding through requirements for Sustainable Drainage Systems (SuDS) and minimising the area of impermeable surface.
Proposed arrangements for SuDS should be adequate for the development and appropriate long-term maintenance arrangements should be put in place.
According to the policy, planning should support developments which showcase six qualities, one of which integrates SuDS “to conserve and enhance natural features whilst reducing the risk of flooding.”
Sustainable drainage reports are a comprehensive analysis of a site to determine its suitability for SuDS, the topography of the site land and data relating to sewage systems in the vicinity.
GeoSmart’s SuDSmart Drainage Reports are offered in three variations, each of which are able to support architects, developers, planning consultants and the legal market.
For more information about local planning authority guidance in your area, please visit our unique catalogue.
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
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:
For more information regarding Sustainable Drainage Systems, contact our team today on 01743 562183.
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).
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.
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.
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.
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.
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.
To discuss the SD50 SuDS screening map and how it can improve your planning submission for your client, contact us today.