Pole position

When Silverstone Business Park needed an effective flood protection solution, it turned to GRAF UK

With its main entrance right opposite the famous Silverstone Circuit, the developers of Silverstone Park designed the facility to attract engineering firms and high-tech companies to the area. Comprising a total of four industrial buildings with 12 individual office and warehouse units, contractors Readie Construction were tasked with finding an efficient and compliant stormwater management system – one that would provide longterm protection against flooding.

Having previously worked together on a number of projects, Readie Construction approached GRAF UK for a reliable, futureproof solution that would comply with the strict run-off requirements of just nine litres per second set out by South Northamptonshire County Council.

To do this, the GRAF UK team specified, designed and installed a bespoke 945m3 EcoBloc Inspect Flex system, comprising five tanks made of around 4458 heavy-duty crates. In line with DEFRA and Environment Agency guidelines (outlined in the ‘Rainfall runoff management for developments’ document), the system was also built with enough capacity to resist the kind of extreme storm only likely to appear once in a 100-year period, with an additional 20 per cent contingency buffer for climate change on top of this.

Water management
Matthew Mayfield, Site Manager at Readie Construction, says: “This particular job wasn’t a traditional drainage project. The challenge here was to find a stormwater management solution that would allow us to drain the water through the natural stream that runs through the middle of the site. The EcoBloc Flex crates were ideal for this, as they have a really straightforward, modular design. We also needed a system that would withstand the load of the heavy traffic coming in and out of the site, and prepare us for the eventuality of flash flooding. GRAF’s EcoBloc Flex modules fit the bill.

“It was also handy to work with a local company based just ten miles down the road from Silverstone. As GRAF UK was able to get on site quickly, it meant we were able to stagger the install. We were responsible for all the preliminary excavation work to prepare the ground for the tanks, and installing the hydrobrakes, which regulate the speed of the water flow coming out of the system. The GRAF UK team then came in to install the water management system. They were absolutely first-class, and as a site manager, I couldn’t have asked for more!”

The EcoBloc Flex modules used at the Silverstone Business Park are made in Germany at one of the most modern production facilities in the world. They have a lorry-bearing capacity of 60 tons with an 800 mm (2’ 7.5”) earth covering, making them the obvious choice for the site, which will see a continuous influx of lorries coming in and out of the warehouses. Each crate boasts a gross volume of 205 litres and can be installed at a depth of up to five metres.

Modular blocs
Matthew Rolph, Managing Director at GRAF UK, says: “This project is a very good example of the real flexibility and environmental credentials a well-designed stormwater system can offer. The tanks’ outlet and inlet being at the same level means we were able to install them at a very shallow depth of just 1.78 metres (with a 1100 millimetre earth covering) – considerably reducing the amount of excavation work required, but maintaining durability for heavy traffic overhead. This also allows for extra storage space, as water can back up into the pipework where needed.

“The large void ratio of the modular blocs also means they can hold more water, without requiring as much valuable space. They can easily be stacked inside each other, saving twice the volume per truck, halving transport costs, and reducing carbon emissions in the process. In fact, we were able to load enough blocs to build five tanks in just eight lorries from our factory in Germany direct to the Silverstone site. It’s been brilliant to be involved in such a highprofile project so close to home.”

GRAF UK Ltd (a subsidiary of German-based Otto Graf GmbH) is a European market leader in the water management sector. The company provides innovatively designed rainwater harvesting, stormwater and wastewater management systems that are manufactured in Germany at one of the world’s most modern and sustainable production facilities.

For more information, please see www.grafuk.co.uk