Introduction
We quite often get asked the above question by developers, therefore to save our team having to answer this again and again, we thought we’d explain this here. But first let’s give you a recap of why these SuDS Report or SuDS assessments are required.
Purpose of SuDS Reports
The purpose of a SuDS report or SuDS assessment to support a planning application, or to discharge surface water run off related planning conditions, is to ensure that your development proposals are not increasing flood risk at your site, or elsewhere.
Importance of SuDS in Urban Development
Increased urbanisation, coupled with more frequent extreme storm events, means that the existing surface water drainage infrastructure cannot cope with the peak rate of surface water run off entering these systems. This leads to flooding, not only of these piped systems, but also flooding of the receiving watercourses, rivers and sea.
You have to have been living in a cave if you haven’t seen the news reports of the devastation caused by flooding, to homes, business and infrastructure in recent times.
Therefore the only way this flooding can be reduced is to ensure that all new developments incorporate SuDS (Sustainable Urban Drainage Systems), as well as retrofitting SuDS at existing developments. However, the latter is another blog for another day. I digress.
You have to have been living in a cave if you haven’t seen the news reports of the devastation caused by flooding, to homes, business and infrastructure in recent times.
Therefore the only way this flooding can be reduced is to ensure that all new developments incorporate SuDS (Sustainable Urban Drainage Systems), as well as retrofitting SuDS at existing developments. However, the latter is another blog for another day. I digress.
Why Attenuation Tanks Are Suggested
We appreciate that any form of new development comes at a cost, and the amount of reports our clients are being asked to complete at planning stage, or for conditions discharge, is increasing, as well as buildings materials becoming more and more expensive.
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Therefore we are client focused, and understand the constraints and pressure our clients are under, however at the same time it is vital that we meet the mandatory requirements of the relevant local and national SuDS policies, in order for your planning application to pass, or SuDS planning conditions to be released. As without this approval, you cannot build your development, or sell the site with planning or planning conditions.
Understanding Permeable Paving
If all new developments can slow down the peak rate of the surface water run off entering the existing surface water networks, and the receiving watercourses, rivers and sea, then we are working together to reduce the flood risk and risk to people’s homes, livelihood and lives.
When planning out a SuDS assessment, our team look at the key requirements of the Lead Local Flooding Authority, Local Authority or SAB (SuDS Approval Body), that your project will be reviewed by. With 13 years of UK wide experience of producing SuDS reports, we are aware of the needs of each of these bodies, and that allows us to present you with a solution that will pass, but also works for you.
When planning out a SuDS assessment, our team look at the key requirements of the Lead Local Flooding Authority, Local Authority or SAB (SuDS Approval Body), that your project will be reviewed by. With 13 years of UK wide experience of producing SuDS reports, we are aware of the needs of each of these bodies, and that allows us to present you with a solution that will pass, but also works for you.
How Permeable Paving Works
So, let’s get back to the original question, and specifically let’s discuss permeable paving! Permeable paving is designed to allow water to infiltrate across the entire area that this provided, via a material that is permeable itself, as well as voids allowing surface water run off through these. This surface water is then stored in a gravel sub-base which essentially provides temporary storage from the voids within the gravel, and thereby allowing it slowly to infiltrate into the ground.
Handling Extreme Storm Events with SuDS
Permeable paving is a great solution for dealing with the surface water run off from lower rainfall events and reduces the peak flow rate of surface water run off from these events entering any gullies or slot drains, especially on flat sites.
However, when a high intensity storm event occurs, the permeable paving will only allow some of the rainwater falling on it to absorb, and the remaining surface water run off will flow off this following the gradient of the site.
However, when a high intensity storm event occurs, the permeable paving will only allow some of the rainwater falling on it to absorb, and the remaining surface water run off will flow off this following the gradient of the site.
Combining Solutions for Optimal Results
As SuDS designers, we are required to design to intense storm events, therefore we can not discount the areas of the proposed permeable paving from our hydraulic calculations to use as a part of the SuDS assessment or SuDS report. Therefore you will require an attenuation tank or soakaway (depending on the underlying ground conditions) to ensure that the surface water run off produced as a result of extreme storm events is accounted for, and no flooding is caused at the site or elsewhere.
Conclusion and Further Assistance
We hope this answers your questions, however if you are still unsure feel free to contact us via email on info@www.nimbusengineering.co.uk. For more detailed information, visit our Sustainable Urban Drainage Systems page.