By Lynda Myer
In order to excavate a new sewer, the Northern Ireland Water’s Belfast flood alleviation project, which’s value is £7M, required shoring for three excavation pits.
The replacing and upgrading process of a 2km sewer tunnel along Ravenhill Road, Ravenhill Avenue, and nearby streets in south Belfast is undergoing by the main contractor Geda Construction. Consultant Aecom> has provided design and project management support for the scheme.
Being part of NI Water’s Ravenhill Avenue Flood Alleviation scheme, this project has been planned to decrease the venture of out of sewer flooding caused by surcharges of the available Victorian brick-lined sewers during periods of heavy rainfall.
Digging process of a new 2m diameter sewer tunnel beneath the busy Ravenhill Road in order to assist the reduction of disruption over construction, was up to Coventry-based specialist contractor Active Tunneling while presenting shoring equipment to support two launch pits and one reception pit for the tunneling works, were Specialist construction solutions firm Groundforce’s duties.
This new tunnel stretches 75m from the edge of Ormeau Park up Ravenhill Avenue and further this point Geda Construction is recruiting more traditional open-cut methods to build the remaining sewers and manholes.
Due to shaping a dog-leg in the street by the intended tunnel, the tunnel boring machine (TBM) cannot navigate around a sharp bend, hence it was excavated in two drives from startup pits at either end towards a reception pit located at the bend in the middle.
Groundforce Northern Ireland area manager Kristian McKinley said: “We designed the pits so that the tunneling machine could be lifted into the excavation without encountering any obstacles.”
He continued: “We also designed them so that once a 200mm concrete base slab had been cast, the lowest frame could be removed and six of the steel sheet piles could be lifted to allow the tunneling machine to enter the ground under the road.”
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