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Caption if needed sdkvjb sdkvjnsdlk dvsdvdvsdvsdvsdv dv skjbdv lskdjvbsdkljvbsdkv W hen Glasgow was hit by severe flooding in the summer of 2002, one city councillor told the BBC: "We've got a 19th century sewer trying to deal with 21st century problems." This summer, a-er nearly two years in construction, a new sewer superstructure – the biggest in Scotland – became operational in the southside of the city. The £100 million Shieldhall Tunnel, which runs 3.1 miles and connects to the existing network at Queen's Park and Craigton, is the crowning glory ONSITE SHIELDHALL TUNNEL 16 WET NEWS SEPTEMBER 2018 | wwtonline.co.uk mitigate flood risk but explored the bigger picture, seeking pos- sibilities to enhance the envi- ronment and boost growth for housing and commercial devel- opments in the southside, which had been slowed by the lack of capacity in the network. The group had initially con- sidered whether to tackle the flooding threat with a series of large-scale, independent solu- tions: an 11,000 cubic metre offline tank, a 1.3km tunnelled outfall to the River Clyde and a new Kinning Park pumping sta- tion with upsized 5km rising main. The Shieldhall Tunnel option – a gravity sewer with minimal ongoing maintenance costs – was ultimately deemed to offer best value and, unlike the alter- native plan, avoided the need for major engineering works around key routes within the city centre. The route for the Shieldhall option certainly had its The Shieldhall Tunnel project cost £100 million Tunnel vision • The Shieldhall Tunnel is Scotland's biggest sewer superstructure. Scottish Water's Dominic Flanagan and Costain's Neil Grosset tell Robin Hackett about the challenges of bringing Glasgow's wastewater infrastructure up to date of Scottish Water's £250 million project to transform the waste- water system in the Greater Glasgow area. Collectively, more than 100 workers spent 1.5 million work- ing hours on the tunnel; the result is a 4.65m diameter tun- nel that provides 90,000 cubic metres of extra stormwater stor- age – equating to more than 108 million litres – while 90 per cent of the effluent that had previ- ously been discharged from the network's combined sewer over- flows (CSOs) into the River Clyde can now be treated at Shieldhall sewage treatment works. As Scotland's Environment Secretary, Roseanna Cunning- ham, said when opening the tunnel in July: "Communities across Glasgow will benefit for years to come from this latest extraordinary feat of engineer- ing which lies hidden deep beneath the city." The 2002 floods had sparked the project into action. A-er dis- cussions as to whether the fault lay with Scottish Water's Victo- rian sewer network or a lack of capacity within Glasgow City Council's storm drains, the two parties came together with the Scottish Environment Protec- tion Agency (SEPA) to form the Metropolitan Glasgow Strategic Drainage Partnership (MGSDP) that year. The MGSDP – which now counts Scottish Canals, Scottish Enterprise and Clyde Gateway among its long list of partners – set about investigating the hydraulic relationship between the city's sewers, storm network and watercourses to gain an understanding of the mecha- nisms for flooding. Over the course of 10 years, the group produced detailed com- puter models of the catchments along with significant survey works, and its 'Glasgow Strategic Studies' formed the basis of the Shieldhall Tunnel plan. "What came from the flood- ing event in 2002 is you can't really place responsibility on one party," Dominic Flanagan, project manager for Scottish Water, says. "It's everybody's responsibility." Making use of the varied per- spectives within the group, the MGSDP did not simply look to Scottish Water's Dominic Flanagan

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