Water & Wastewater Treatment

WWT May 2016

Water & Wastewater Treatment Magazine

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Page 14 of 39

www.wwtonline.co.uk | WWT | MAY 2016 | 15 Project focus Pumps and pumping systems Construction off-site key for Severn Trent pumping station replacement Project focus T he sewage pumping station at The Heage, Sotshole is a relatively small cog in the Severn Trent network, serving around 330 customers living between the village of Heage and the town of Belper, in Derbyshire. The existing station consisted of a ● Derbyshire pumping station needed replacement because of insufficient capacity ● Off-site prefabrication preferred to overcome restricted space challenge ● Innovation design meant only 11 days on site pumping station offered less than two hours of storage at three times dry weather flow and, should pump failure occur, the surcharging system would result in pollution incidents to the brook. Alongside this fundamental issue, the existing mechanical and electrical equipment was deteriorating and was no longer compliant with our own internal standards, further increasing the risk of pollution due to pump failure and blockage. In addition there was a clear risk to our own personnel due to the general decline of the pump station. We therefore received approval to replace the pumping station as a matter of priority. However, it was not a straightforward job for ourselves and for our lead design and build contractor, NMCNomenca. We faced a number of issues: • The existing wet and dry wells had to be abandoned; • Existing mechanical and electrical assets had to be decommissioned to remove any potential hazards; • We were working in a compound that was next to an area of ecological importance; and • The compound itself had limited storage for materials and waste. The last of those problems, the restricted nature of the compound, led to the project team proposing an innovative design that would result in an entirely prefabricated solution that could be liˆed into place piece by piece over the course of just 11 days. It would be manufactured off-site, with an extended design phase ensuring reduced health and safety risks and improved environmental credentials over the construction and future operation of the asset, together with the 20% improvement in efficiency we called for as part of our AMP 6 plans. The new design called for a 3.5m diameter, 4.5m deep chamber to allow wet and dry well topped by a brick superstructure and had an emergency overflow chamber located within the compound, which was made up of a separate storm well with an overflow to the nearby brook. The problem that we, as a company, had was that the existing Frank Thompson, ProgrAMMe DeliverY leADer (eAsT), severn TrenT The Weholite wet well was constrcuted off-site • Drivers ● pumping station needed replacement to boost capacity in wet weather. ● restricted compound and environmental considerations called for off-site construction. ● Concrete cover with access points ensured ease of long- term maintenance.

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