James Parker speaks to Burdens’ national sales director Ken Graham, technical sales manager Andrew Taylor, and director of technical solutions Mark Gillies. They tackle the key questions on how developers can take a more holistic approach to stormwater management, the role of natural and engineered SuDS, and how specialist expertise can help projects save time, cash and carbon.
Why is stormwater management becoming such a critical issue for housebuilders & developers, particularly in the context of the 1.5m homes target & the need to build on flood plains?
Graham: Stormwater management has become critical because of the increasing frequency of severe weather events and the pressure this puts on traditional drainage systems. When those systems are overwhelmed, we see the consequences in the form of serious flooding.
At the same time, development has replaced areas of open land where water would previously have naturally soaked into the ground. We are now dealing with much larger volumes of water entering an ageing drainage system, so every development needs to consider how that water is going to be managed and attenuated.
We are seeing more intense rainfall and heavier downpours, which has increased the need for SuDS and systems that can manage water more efficiently. With millions of properties already at risk of flooding, it really highlights why these solutions need to be planned, designed, installed and maintained properly.
Can you break down what constitutes stormwater management as an overall strategy for a development?
Taylor: There isn’t one single solution. The most common approaches include underground attenuation tanks and soakaways, which store water and release it at a controlled rate. But there are also swales, detention basins, retention ponds, permeable paving, rain gardens, and rain planters.
The important thing is to look at the development holistically – you can have several of those solutions working together. A large underground tank might provide the bulk of the storage, while
rain gardens, permeable paving or smaller soakaways deal with water at the individual plot level.
Even the more natural-looking solutions have an engineered element behind them. There are calculations around how much water each feature needs to store and how it will perform during a storm event. So it’s about combining the right solutions for the site rather than automatically choosing one approach.
How do you decide on the balance between natural and engineered or below-ground SuDS in each development?
Graham: It really comes down to what is right for that particular site. Two contractors looking at the same piece of land could potentially want to attenuate the water in completely different ways.
That’s where we come in. We’re not trying to push one particular solution. Our role is to understand what the developer or contractor is trying to achieve and then offer the right solution for that situation. The site, its topography, available space, cost and the overall design all have an influence.
Sometimes a development will benefit from a larger natural feature, while on another site there simply isn’t the space, and an underground solution makes more sense. It’s about finding the right balance.
How do natural SuDS features help to increase the resident appeal as well as biodiversity of developments, And why is this important in the current market?
Gillies: When SuDS are done well, they can transform the amenity value of a development. Ponds, swales and other green solutions can support biodiversity and wellbeing, while also making a development feel softer and more natural.
There is a real opportunity to create developments that feel more balanced and liveable rather than simply being rows of houses surrounded by hard landscaping. Natural SuDS can help retain some of the character of the land while also providing a genuine drainage function.
For developers, that’s important because these features can become part of the wider proposition of the development. A pond or swale isn’t simply somewhere to put excess water; if it’s designed properly, it can become an attractive and multifunctional part of the environment.
Is it very difficult to incorporate comprehensive natural SuDS in tight urban sites?
Gillies: It can be challenging, particularly where space is constrained, but that’s where taking a holistic approach becomes important. Natural solutions such as ponds and swales can take up more space, whereas underground storage allows developers to make better use of the available land and potentially create more room for plots.
The answer isn’t necessarily to choose natural or engineered solutions. It can be about combining them. You might have a larger underground system dealing with the bulk of the storage while incorporating smaller-scale natural features such as rain gardens or permeable paving elsewhere across the development.
The earlier those decisions are made, the more options the developer has available.
Why is early-stage thinking on SuDS important and who typically takes charge of design?
Taylor: It needs to be considered at the earliest possible stage, ideally during concept design and planning. If you know you want ponds, basins or swales as part of the development, the housing layout needs to work around those features rather than trying to find somewhere to put them once the houses have already been designed.
Looking at it early allows you to consider how much land is required, what the costs are and what you want the development to look and feel like. If you leave it until the end, your options become much more constrained, and you can end up trying to shoehorn drainage features into whatever space is left.
It should be part of the wider design process, with the developer, designer, contractor and relevant specialists working together, rather than treating drainage as something that is added at the end.
What advice would you give to developers who want to take a more proactive approach to holistic stormwater management but are unsure where to start?
Gillies: Start as early as possible.Concept planning, detailed design and construction all need to be considered as part of the same process.
The earlier SuDS are embedded into a scheme, the more cost-effective the whole process can be. If you wait until construction is under way, you may have to go back, make changes and alter specifications, which costs both time and money.
It’s also about getting the right people around the table. If everyone works together from the outset, you can look at the different solutions available and make sure the final approach is practical to install, cost-effective and appropriate for the site.
What about maintenance – who maintainS SuDS INSTALLATIONS, And what happens if maintenance isn’t factored into design?
Taylor: Maintenance is absolutely critical, particularly for systems that are buried underground and out of sight. We’ve seen drawings for attenuation tanks where there isn’t sufficient access for inspection or maintenance. If you can’t get into a system, how are you going to clean it and keep it performing properly?
The same principle applies to above-ground drainage. You can see existing schemes where road gullies or channel drainage have become blocked because they haven’t been maintained. The design may have been perfectly adequate, but if the system isn’t looked after, its performance will decline.
With underground attenuation, silt, fines and oils can build up over time, reducing the available storage capacity and potentially causing problems further down the network. So access for inspection, cleaning and maintenance needs to be considered as part of the original design, rather than treated as an afterthought.
What are geosynthetics and why do they play an important role in SuDS?
Gillies: Geosynthetics are typically man-made polymers used as value-engineered alternatives to traditional construction methods. One of their key functions is filtration, which makes them particularly well suited to SuDS applications.
They’re still relatively underused when people are considering SuDS. For example, grass and gravel pavers made from recycled plastics can provide a permeable surface that allows rainfall to pass through naturally, removing the need for some traditional drainage infrastructure.
They can also be used as part of the layers beneath the surface, alongside geotextiles, sub-base materials and, where required, geogrids. Non-woven geotextiles, for example, provide strong filtration properties.
The wider benefit is that geosynthetics can reduce the volume of traditional stone required, as well as reducing installation time and the need to mobilise heavy plant. That can have a significant impact on time, cash and carbon.
Why is there an issue around products in the market without clear accreditation?
Gillies: Developers need confidence that the products they’re specifying are going to perform as intended. There are products on the market where the information provided may be based on a manufacturer’s data sheet rather than being supported by the appropriate declaration of performance or relevant standard.
That can make it difficult for specifiers to understand exactly what they’re getting and how the product compares with an established standard.
For example, Burden’s Aztex MW100 non-woven geotextile meets the BS 8661 standard. Having the appropriate standards, accreditations and supporting documentation gives designers and contractors greater confidence in the performance and suitability of the product.
What other product types have seen recent innovation that is helping residential SuDS projects achieve success?
Taylor: There have been developments across a number of product categories. With modular attenuation systems, for example, manufacturers have been increasing the void ratio of some products, allowing them to hold more water within the same overall volume. That can help reduce the footprint of a tank.
We’re also seeing more use of rain gardens and planters at individual properties, permeable paving and tree pits. There are developments in crate systems too, including shallower options that can provide greater flexibility where depth is restricted.
The important thing is that developers and engineers don’t necessarily have to accept the first solution presented to them. There may be another product or approach that reduces the footprint, eliminates the need for additional tanks or makes the installation easier.
What is the expertise that Burdens can bring to projects to assist specifiers in saving ‘time, cash & carbon’?
Graham: Our role is to bring together technical, logistical and product knowledge to help contractors find the right solution for the scheme. We’re not simply there to sell a particular product. Sometimes the right solution may actually mean we sell less, but if it’s the right solution for the customer and the project, that’s what we should be doing.
We’ve seen projects where changing the design has dramatically reduced the number of deliveries required, while also reducing cost and carbon. In one example, a design change reduced the number of wagon movements from around 97 to around 17 while achieving the same overall solution.
That’s the value of looking at the whole project rather than simply pricing what’s on a drawing. Andrew and Mark can look at a design and ask whether there’s a different way of achieving the same outcome, whether the footprint can be reduced, whether installation can be simplified or whether the amount of material and site movements can be reduced.
We’re effectively acting as the link between the developer, contractor and manufacturer, bringing those different areas of expertise together. Ultimately, it’s about understanding what the customer is trying to achieve and finding a solution that works technically, commercially and practically.
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