Client: Kybotech timber processing plant
Type of works: installation of sustainable drainage system.

The sustainable drainage system developed by ACO Water Management for Kybotech’s new timber processing facility in Nottinghamshire fully integrates a number of SUDS processes to successfully overcome the site’s many challenges.

Situated in a restricted low-lying position close to the watertable, the system first removes all oil deposits and sawdust carried in run-off from both the handling yard and the building’s roof then attenuates the clean surface water to ensure it can be lifted to an adjacent stream at the specified safe discharge rate that prevents any downstream flooding.

Kybotech is one of the UK’s leading manufacturers of garden sheds and outdoor buildings. Established in 2000 the online retailer has grown rapidly, expanding into a wide range of home, garden and leisure markets. In order to meet demand from its seven online retail stores, the company has invested in the expansion of its manufacturing base in Sutton-on-Trent, Newark.

“The engineers needed to work with our design services team to realise a drainage scheme that could be installed within a severely limited space, be capable of withstanding the direct loading of HGVs and have the ability to handle potentially high levels of surface water contamination,” says Jon Croke, Head of Design Services at ACO Water Management. “ACO’s experience in integrating the processes required proved decisive. The team were able to produce a detailed, value-engineered solution that demonstrated how we could not only meet the specification but achieve it with minimal ground infrastructure and cost.”

A combined total of 400 metres of ACO Qmax® 225, Qmax® 350 and Qmax® 600, all fitted with Load Class F900 edge rails, collects all the run-off generated from the handling yard together with a percentage from the roof. Having passed through an oil separator, the outflow is joined by the remaining run-off from the roof before entering a 600 cubic metre attenuating ACO StormTank located beneath the yard’s concrete pavement.

A ‘silt tunnel’ incorporated within the ACO StormTank captures all sawdust and surface debris that enters the system, alleviating the possibility of any solid contamination passing into the natural watercourse. The tank is also fitted with a level switch that controls an adjacent pumping station which lifts the clean and clear water from the tank at a low flow rate to the discharge point at the stream.

“The hydrological conditions at the site placed tough limiting values on the depth of attenuation tank we could use. To achieve the overall system capacity required we needed to maximise volume within the carrying infrastructure,” says Jon Croke. “The Qmax® system is designed for just such an application as it combines both a high carrying capacity with Load Class F performance. The flared inlet neck of the system is also ideal for situations like those faced at Kybotech where there is a lot of surface debris which can block conventional inlet designs.”

ACO StormTank has a unique ‘open-sided’ cell structure design that uses high strength central pillars and side walls to provide load bearing capacity and structural integrity. A completed tank only requires side panels at its perimeter to provide lateral support. The result is a totally barrier free interior void that can be easily accessed, inspected and cleaned. The free flow of storm water entering the tank also avoids having to use expensive pipe manifolds and additional pipework to distribute flow evenly.