From March 2023, storm tanks in the UK must adhere to new minimum capacities in order to qualify for discharge permit renewal, which vary according to the site. For some clients this involves replacing tanks with larger ones, or building new tanks that link to, and work with, existing infrastructure.
A site in the North of England required just 12 cubic metres of additional storm flow retainment capacity to reach the new EA storm capacity permit. The first option discussed involved raising the overflow pipe within the tank – as the walls were of sufficient height – but this would have required a more extensive programme involving concrete works and increased the risk, cost, and carbon footprint.
Working together, the client and Stonbury’s designers provided an alternative solution to install a three-sided steel weir box around the tank overflow outlet. Scanning and computer modelling enabled the team to calculate the required dimensions. The resulting box was just 110mm high, holding the equivalent of 12 cubic metres of water – providing the exact volume of additional capacity required.
Fabricated off-site and installed within half a day, the solution for this tank offered a safe, effective and economical way for the client to achieve the new EA storm volume. The client was delighted.