Ecobuild 2015 – Interview with Sue Illman Part 3

How do you approach a SUDS design?

It’s absolutely about just understanding the site. So we’re talking Greenfield site here.

So the first thing you absolutely have to understand is the topography, because strangely enough water flows downhill as fast as it possibly can in the most direct move that it can. So you have to think about how the water naturally flows through the site, because if you put a building in the wrong place, even sites uphill can flood because you put it in the wrong place and the water will go in the backdoor and out the front door, no problem.

So we would look at topography and how we want to collect water across contours and how we’re going to convey it and where we’re going to take it to at the bottom of the site and where we’re going to discharge it. So that’s the simple approach.

As a landscape architect, if I’m master planning, then I’m going to be looking at trees, and hedgerows, and all the natural features, and the elements at the same time. And we’re going to start to allocate areas of the site to what the uses might be, understanding how we’re going to collect the water and how we’re going to store it and where in principle, but also because we want to have a hierarchy of measures in terms of our SUDS. Because if we put water through green systems, then we get improvements to water quality as it comes down the chain, what’s called the management train.

So we want to have a number of interventions that it goes through. And also we want to have a lot of these features and make them as close to where the water is falling on the ground, because the sooner we can intercept it, the sooner we can deal with it. So we’re looking at multiple interventions spread through a site in a hierarchy that all comes down towards the bottom of the site or where it can discharge. So if you’ve got waterfalls running along the site, you might have several or multiple discharge points. If you’ve got a single point where you can discharge or overflow from, then it will be towards the bottom or wherever that is.

All of these designs are completely one-offs for a site. There is not a standard solution. What there is is there’s an approach, and that it’s down to dealing with it on the ground.

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