Conducting a SuDS report on your development is often stipulated as part of the planning approval process, but what are the other key reasons why having a SuDS strategy is crucial for planning approval?
A Sustainable Urban Drainage Strategy (SuDS) is the consideration of managing surface water drainage and flooding at a new development site. Sustainable drainage systems aim to mimic natural drainage while reducing flooding by catching or storing it where it falls.
SuDS are crucial as part of planning because local authorities and the UK Environment Agency are very concerned with the rise of local and national flooding, and the impact that can have on people and their property.
As more sites across the UK incorporate SuDS into their design and construction, we can collectively reduce the pressure on traditional piped drainage and decrease the risk of flash flooding.
Continue this article to discover when to expect SuDS as part of new developments and other key reasons why a SuDS strategy is crucial for planning approval.
When is a SuDS Strategy Stipulated in Planning Applications?
A SuDS strategy is required if a development meets the following conditions:
- A development with more than 10 dwellings.
- Commercial Floorspace over 1000m2.
- Development is within an area at risk of flooding, or within an area identified as having critical drainage problems.
- The specific local authority requires a SuDS report as a part of the validation process.
But what about developments that don’t meet these stipulations? Is a SuDS or Surface Water Drainage Strategy a condition of their planning permission?
Well, it is becoming increasingly important to demonstrate to the Local Planning Authority and the Lead Local Flood Authority that surface water drainage has been considered in most new developments.
A sustainable surface water drainage strategy benefits the environment, reduces the risk of water pollution and flood damage, and also contributes to improving wildlife and biodiversity in urban landscapes.
Why Is A Suds Strategy or suds report Important as Part of Planning?
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The Site Development Has A High Water Table or Clay Based Soil
Although not always deemed an area with a high risk of flooding, regions of the UK with a high water table or clay-based soil can be at risk of flooding.
Heavy clay-based soil impacts the soil infiltration rate, meaning water takes longer to soak away. This can often mean certain elements used in a standard SuDS strategy are no longer effective, so more work is needed to overcome flooding risk.
In such a scenario, it might be an additional aspect to focus on, including connecting your development to the storm drain. In some cases there are sites with heavy clay and therefore deeming infiltration based SuDS unfeasible, and without a storm drain nearby. Therefore the local authority would like to be satisfied that SuDS are feasible at your proposed development site, and should the underlying geology be unsuitable for infiltration, that there is somewhere for restricted surface water run off to be conveyed to.
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Your Specific Lead Local Flood Authority (LLFA) Requires One
A SuDS report or SuDS Assessment is often required due to local planning policy as well as the view of The specific Lead Local Flood Authority (LLFA) and the local planning policy. They can determine drainage as a critical issue in your area, and make a SuDS report a requirement of planning.
The level of detail required can vary for each LLFA, some are happy with a basic SuDS report that provides an outline of SuDS strategy in writing, supported by hydraulic calculations and a desktop infiltration study. Some LLFAs will also request a full Sustainable Urban Drainage strategy to include an outline foul drainage strategy also.
Whereas, some LLFAs also request detailed drainage layouts to include pipe sizes, cover and invert levels of all manholes and SuDS, all provided in proposed layouts and include connections to existing systems.
When we have been instructed on these, we liaise with the client and architect to ensure we can develop the proposed solutions through to the planning condition discharge and construction stage without repeating work or carrying out abortive work, meaning the client does not end up paying for the same service twice.
Due to our many years of experience in this field, we are aware of which local authorities request SuDS reports for planning applications, from minor extensions to larger developments. Therefore we can inform you of this and the level of detail required by each.
On occasions, our clients tell us about a cheaper quote they’ve received elsewhere, but the clients find that their appointed consultant is not aware of the requirements, leading to the planning application being refused or the appointed consultant charging extra to meet the specific requirements of the LLFA.
SUDS REPORT
A SuDS Report containing a viable SuDS strategy is often a crucial element of any new development, even for minor extensions, but there is no need to panic if there are planning stipulations on your development.
In many instances, a Sustainable Urban Drainage Strategy can be implemented into a development easily and at a lower cost than traditional drainage systems, especially when considered in the early stages of a development project.
Choose Nimbus for your SuDS Design
As Civil Engineers and Environmental consultants, we can give you early-stage advice for sustainable drainage designs to practically integrate into your development, allowing you to work around any constraints or risks, in a natural and ecological way.
Nimbus can provide you with SuDS reports and assessments to give you an excellent SuDS strategy, with the required level of detail, to minimise surface water run-off from your proposed development, helping you achieve planning application approval. Talk to us today!