ACO StormTank is the first modular storm water infiltration and attenuation system to fully overcome the problems created by silt build up and provision of tank access for inspection and maintenance. Developed by drainage and water management specialist ACO Technologies, ACO StormTanks unique open-sided cell structure allows access to every part of the installed tank and, in combination with special geotextiles, can be configured to remove the risk of silt build up and blockage, ensuring the long-term, effective performance of the installed system a major issue in securing site development approval.
ACO StormTanks innovative design uses high strength central pillars rather than 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.
Manufactured from a lightweight, 100% recyclable material, ACO StormTank is tested to CIRIA guidelines and is suitable for both landscaped and trafficked areas such as car parks, retail parks and residential developments. Available in three depths (457mm, 610mm and 914mm), ACO StormTank cells can be used to create a storm water storage unit configured to any capacity, discharge requirement, soil condition or land area.
With the frequency and intensity of storm rainfall patterns increasing, surface water management on all new build developments is now a vital issue for the planning authorities, says Neill Robinson-Welsh, Business Manager at ACO Water Management. As the long term viability of ACO StormTank overcomes the barriers that have hindered the adoption of such systems in the past, contractors can now capitalise on the full benefits of its lightweight, modular cells that are easy to handle and install and, with a high 97% void ratio, require less soil excavation to achieve the required capacity.
In combination with a suitable geotextile or geomembrane, ACO StormTank can be easily configured to either infiltrate or attenuate run off depending on the specific environmental and planning requirements of the location.
To act as an infiltration system where surface water is returned directly to the surrounding soil and groundwater, the ACO StormTank should be wrapped in ACOTex - a polypropylene, non woven permeable geotextile. Additional internal side panels and ACOTex can be incorporated around the tank inlet to provide a forebay that contains any sediment build up where it can be easily removed, ensuring the system does not become blinded and ineffective over its design life.
For attenuation, surface run off needs to be released from the ACO StormTank at a controlled rate into the main sewer or watercourse in order to prevent storm surges and subsequent flooding downstream. Encasing the tank in an impermeable ACOWrap geomembrane and covered with a protective ACOTex Plus fleece achieves the watertight, stable installation required.
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.