Contractor: F. Espley & Sons Ltd
Type of works: first ACO StormTank installation completed at engine manufacturers site in Stafford.
The first installation of the new ACO StormTank modular surface water attenuation and infiltration system has been completed at Perkins Engines manufacturing facility in Stafford. A key part of a sustainable drainage system (SUDS) designed by ACO Technologies, the 65m3 modular tank system attenuates and controls the discharge of surface water run-off from a new lorry park that has been created to ease vehicle movements across the site.
Installed beneath the new concrete hardstanding, the watertight tank receives run-off (via an oil interceptor) from a single 65m run of ACO S100 heavy duty surface drainage channel situated along one side of the park. From the tank, water is discharged to a nearby stream at a controlled maximum rate of 3 litres/second. During heavy rainfall, excess water held back by a vortex control in the outlet chamber accumulates within the tank, releasing over time as rainfall conditions ease.
The ACO StormTank was installed by Stafford-based contractor F. Espley & Sons Ltd. As Andrew Bramall, Contracts Manager, explains, the modular system delivered particular site benefits: As the system has such a high void ratio, we were able to reduce the total volume of the excavation required to accommodate the tank a significant time and cost saving. It was also extremely easy to handle; the lightweight, modular design meant that we were able to assemble the entire tank in under a day.
ACO StormTank is the first modular storm water infiltration and attenuation system to fully overcome the problems created by silt build up and the provision of tank access for inspection and maintenance. Its unique open-sided cell structure provides access to every part of an installed tank and allows it to be configured to remove the risk of silt build up and blockage, ensuring the long-term performance of the installed system.
Its innovative design uses high strength central pillars 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.
In combination with a suitable geotextile or geomembrane, ACO StormTank can be configured to either infiltrate or attenuate run-off depending on the specific requirements of the location. The tank installed at the Perkins Engines site is set up to attenuate all surface water. To achieve the watertight installation required, the tank is first wrapped in an impermeable geomembrane. It is then covered with a protective ACOTex Plus fleece to achieve a completely sealed and stable structure.
If necessary, additional side panels and non-woven geotextile can be incorporated within the attenuation structure to create a sediment tunnel that directs the first flush of any storm straight through the system to a downstream manhole where larger debris can be captured and removed. This alleviates the possibility of the system becoming blocked by ensuring that sediment is not allowed to accumulate within the system over the long term.