Water & Wastewater Treatment

Effluent Pipeline www.wwtonline.co.uk | WWT | march 2015 | 15 Stanton Bonna. "We procured the pipes ourselves, which we think saved us about £1M," says Grimwood. "We brought them upfront, partly because of timescales – if we'd le• it until the start of the contract period, there's no way the contractor would have been able to get the lead-in time to buy them for us to be able to deliver it in 2014. In the process of doing that, we adopted all the risk of pipe supplies, but it saved a significant amount of money." Construction started on April 2014. The 'design and construct' nature of the main contract gave the project team the flexibility to make design changes on site; there was an op- portunity to do this when they realised they could make use of a section of abandoned underground piping near Langford Works which was still in good condition. By tapping into the abandoned pipe at either end, they saved themselves the need to lay a fur- ther 1km of new pipeline, and removed the need to dig along a section of the route which included a conservation area, the churchyard of a 12th century church at Ulting, and private back gardens. "The project team were really in tune with each other - everybody got on really well and was adaptable where needed. Because it was a D&C contract, a lot of the design decisions were being made on site, and every- body really put themselves out to make it work," says Grimwood. River crossings The route included six open-cut road crossings, and two river crossings of the River Chelmer, of 30m and 50m in length. The team were planning to use directional drills for these crossings, but because of the ground conditions, decided on a digger shield method. A sha• of 8m in depth was dug at the river's edge and then 1200mm diameter pipe jack/digger shield machinery, provided by F&B Trenchless Solutions, was used to tunnel underneath the river. With six or seven lorry loads of concrete pipes arriving a day along narrow country roads, communication with local people about the project was important, via letter drops and council liason. The logistics of delivery also provided a challenge, as Gareth Two- hey, national sector manager, utilities at Keyline, explains. "Due to the predominantly single lane country road access, our lorries couldn't park, so deliveries had to be staggered," says Twohey. "We took the • Perspectives Paul Grimwood, Project manager, Essex & Suffolk Water: "It was a successful pro- ject which came in under budget. The project team were really in tune with each other - everybody got on really well and was adaptable where needed." ford site and the estuary, a feasibility study established that a gravity pipeline constructed from concrete was the best solution, which meant that the project team were committed to following the same route as the existing pipeline. "The existing pipeline runs along the river valley, so there was not really much chance of following a different route," explains Grimwood. "There were some slight variations if we were willing to pump the effluent uphill, but once we settled on a gravity solution we were pretty much committed to the line of the existing route." Irish firm Roadbridge were ap- pointed as the lead contractor for the £4.25M project following a tender pro- cess; Turner and Townsend acted as cost consultants and Mott MacDonald were design consultants. Unusually, E&SW decided to procure the concrete pipes for the project themselves, from supplier Keyline and manufacturer above: The 1400mm concrete pipes laid along the route between chelmsford and Langford Gareth Twohey, National Sector manager, Utilities, Keyline: "The length of concrete pipe supplied to the scheme makes it certainly the largest project of its type seen recently. It was a challeng- ing project, with difficult construction sites, which required carefully timed deliveries." Effluent Pipeline

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