Project in focus

Project Category:Infrastructure, Rail
Project Name:Contract C233 Enabling/Advanced Works
Client:Consulting Engineers Bechtel Ltd acting for Crossrail with the Main Contractor J. Murphy & Sons Ltd.
Location:North Woolwich, London
Value:£700k for total project
Project Brief:The McAllister Group was engaged in 2012 by the Project Contractor J. Murphy & Sons Ltd.
Client Brief:A requirement to ensure that all existing and new sewer networks were structurally lined to protect them from potential damage during the nearby construction works on the main tunnel. The linings had to ensure that existing and new pipes were protected against aggressive effluents.
Issues to consider:Both the McAllister Group and J. Murphy & Sons were scheduled to carry out works concurrently which posed difficulties including deep excavations around the lining launch manhole with exposed existing services such as gas, water and electricity. Consideration needed to be given to the request to minimise the impact of works. Temperatures during the work period in May were very high (in excess of 25 degrees) which could potentially damage the liner solution. The sewers were categorised as Category C indicating that the sewer effluent was both aggressive and harmful.
Works preparation:CCTV Investigation and Flow sampling. The McAllister Group had to construct platforms and slides around exposed pipes, mains and cables to avoid damaging them whilst installing the liner.
Our Solution:The design solution agreed was the installation of liners of 1,200mm diameter at all locations on the main trunk and the installation of liners ranging from 225mm to 900mm on a number of branch lines. The use of UV CIPP lining solved the problem of both contractors being on site simultaneously. Each section of 1,220mm liner was installed in a single 12-15 shift. One section of sewer required lining that was a 1,650mm x 1,000mm Elliptical shape. The introduction of a special wheel-set allowed the powerful Blue Tec UV light-train to remain central in the pipe providing an even distribution of UV to heat and cure the liner. The lining manufacturer, Impreg, was able to produce the liner with a vinylester resin and part 1 peroxide which would help cure the outer layers of the liner. Affected by heat, the peroxide liners were staggered to arrive on site in refrigerated trucks and to be installed immediately. The danger of working in Category C sewers necessitated that the McAllister installation teams utilise full body PPE and full breathing apparatus (BA). Working with Thames Water, the McAllister Group addressed the need to divert flows away from the 1,220mm sewers at the site. The existing flows were diverted to a Victorian culvert which was used as a channel. The flows were then pumped back into the main sewer further downstream.
Outcomes:The company’s innovativeness and the use of quality equipment and materials allowed all problems and issues to be addressed and overcome. The project was delivered on budget and on time over a 7-week programme of works. The work undertaken by the McAllister Group involved at the time, the largest liner installation anywhere in the world using UV technology from crown to invert. Management of the communication with residents and businesses was handled successful by the Main Contractor.