Portsmouth Transfer Tunnel

Client: Southern Water/Edmund Nuttall
Project Value: £154,000
Scope:

An Iseki slurry machine system was used to install an 8m long x 1500 dia pipe jacked connection between a 6m dia storage shaft and a 10m dia pumping station shaft, both 30m deep,  at the end of a 8km x 2.8m dia sewage transfer tunnel. 57Nm2 fibre glass reinforced concrete “soft eyes” were constructed in each shaft at exit and entry points into the loose sand ground conditions, with a 30m head of water. In addition, to overcome the ingress of water problems, both sealing arrangements were equipped with double diaphragm rubber seals with additional inflatable rubber seals as a precautionary measure. The reception shaft seal was constructed within a “Top Hat”, designed to house the incoming 1.8m OD x 3.5m long, 18t microtunnel machine, which was filled with water to balance the high pressures during entry. The jacking system was equipped with a hydraulically powered band clamp to fit around the machine/pipes to secure them in place during pipes changes and prevent the machine being “champagne corked” back into the drive shaft during installation. The actual tunnelling took two days to complete instead of the programmed five.

Portsmouth Transfer Tunnel

Portsmouth Transfer Tunnel

Portsmouth Transfer Tunnel

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