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Caption if needed sdkvjb sdkvjnsdlk dvsdvdvsdvsdvsdv dv skjbdv lskdjvbsdkljvbsdkv Flanagan says. "In Glasgow, the geology is very mixed and can change rapidly. There's not a lot of tunnels in Glasgow and there's not a wealth of literature regarding the ground." In the face of all these chal- lenges, Scottish Water sought outside expertise through a Costain Vinci joint venture that combined UK and European civil engineering specialists with extensive tunnelling pro- ject experience. "There was a recognition from Scottish Water that this project was outwith the skillset of our own internal framework suppliers, so the decision was taken to competitively tender the project," Flanagan adds. Explaining the particular skills of the main contractors, Costain project manager Neil Grosset says: "Vinci's strength is very much in slurry tunnel- ling. Costain, as well as tunnel- ling experience, brought the UK element, dealing with the civil construction work and the interfaces with Network Rail and Transport Scotland." The Costain Vinci JV brought in AECOM to coordinate the design of the tunnel and its ancillaries, while Halcrow – later acquired by CH2M, which has itself now merged with Jacobs – worked client-side with Scottish Water to offer guidance. "It was very much the expe- rience of the teams and the tun- nel machine operators that ensured this was completed successfully," Flanagan says. The Glasgow Tunnel Part- nership, as the group was known, had a co-located office on site and Flanagan adds: "That was a key part for us – ensuring we were all working together. It was all about collab- oration and risk management, making sure we were dealing with issues when they arose." For the rail and road cross- ings, Network Rail and Trans- port Scotland were invited to work at the office. "There was a lot of time spent with Network Rail," Flan- agan says. "We had the approv- als in principle in place but ONSITE SHIELDHALL TUNNEL 18 WET NEWS SEPTEMBER 2018 | wwtonline.co.uk then it was down to the engi- neering capability and how we deliver while keeping the rail- way safe and operational up above us." As Scottish Water had opted for a gravity sewer, the depth at the opening of the tunnel needed to be relatively shallow, which presented particular problems when crossing the first railway line. Grosset says: "The fall between the two connection points is only 4m, so you've got a 4m fall over 5km of tunnel, and the Paisley Canal railway was the point where we had the lowest cover between the crown and the existing ground level. Having a 4.7m diameter tunnel where you've only got 3.7m of cover is quite a challenge. The ground conditions under the railway were also challenging." Flanagan adds: "A lot of work was put into satisfying Network Rail that we had an engineering solution to be able to deliver that piece of work safely." There was a sizeable task in managing disruption to the public, too, but Scottish Water spent three years on a commu- nication campaign to raise awareness and forge links with local community organisations. "One of the key aspects was that very early on we recognised that we were going to be disrup- tive to that local community," Flanagan says. "We actually built a new haul road into the site, which took away a lot of that major traffic problem from the local community. Doing that prior to commencing our work gave us a lot of credibility. "It wasn't just the tunnelling work though. Before the project could get up and running, we spent nine months infilling his- toric mine workings in three dis- parate areas along the route. It was a very disruptive bit of work – noisy, dusty – and that was the first bit people saw. "Trying to get over that hur- dle was difficult, but the record speaks for itself – we've done the largest communications campaign Scottish Water has ever undertaken and had no complaints from the local community." With minimal disruption, the Shieldhall project has – in Rose- anna Cunningham's words – "brought a 19th century struc- ture into the 21st century", and its success owes much to the initial planning phase. "MGSDP set the direction for the project," he says. "It's all of the stakeholders collectively agreeing what is required via value management studies – it's effectively a co-owned solution. "That model of local author- ity working alongside the regu- lator and ourselves is now seen as a blueprint and has been starting to roll out into other Scottish cities as well. "It means there's no question – everyone's bought into the solution and agrees it's the right solution. "That brings about efficient investment for the public pound." Herrenknecht delivered the TBM The route crossed three parklands PROJECT SPECS • Reduce risk of internal and external sewer flooding at approximately 150 locations • Improve spills causing downgrading of water quality in receiving waterbodies at approximately 60 locations • Address aesthetic impacts of sewer debris in receiving waterbodies at 350 locations • Minimise disruption to residents during construction phase • Minimise maintenance costs THE VERDICT "You were having flooding that should occur on a 100-year basis occurring almost every year. The tunnel not only alleviates the flooding, which opens up all those areas in the southside for development, but improves water quality in the River Clyde." Costain project manager Neil Grosset The TBM spent 15 months creating the tunnel

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