The TBM has installed a 252-metre-long tunnel and section of water main from Broomloan Road in Ibrox, in the shadow of Ibrox Stadium, to the north side of Bellahouston Park.
The tunnel, which goes below the M8 motorway, Paisley Road West and the Glasgow-Ayr railway line, is part of more than seven miles of new water mains being installed in a project that will connect the water supplies of the Glasgow and Ayrshire areas to increase resilience and protect supplies.
Connecting the networks will provide a two-way water supply between the Milngavie water treatment works (WTW) system in Glasgow and the Bradan WTW system in Ayrshire. In the event of a disruption to water supply in either region, the new system will allow water to be transferred in either direction.
The hand-driven TBM installed the tunnel at a depth of up to 20 metres below ground. It excavated 1,311 tonnes of rock – mostly sandstone and mudstone, which went to landfill – and installed a 100 sections of pre-cast concrete pipes each measuring 2.5 metres in length.
The project is being delivered for Scottish Water by Caledonia Water Alliance, a joint venture of Morrison Utility Services and Aecom, and is expected to be completed in 2024.
The new water main is being installed in the Ibrox, Mosspark, Pollok, Priesthill, Nitshill and Parkhouse areas of Glasgow and will run from Ibrox to a reservoir storage tank in the Parkhouse/Darnley area.
A new pumping station is being built at Ibrox which will push water to the existing pumping station in Parkhouse/Darnley for onward distribution to Ayrshire. This work in the south of Glasgow is the third and final stage of the overall investment, which has already delivered improvements in Ayrshire.
Four tunnels – one at Ibrox under the M8 motorway and the Glasgow-Ayr railway line, another under the Paisley Canal railway and White Cart Water, another under the Glasgow-Barrhead-Kilmarnock railway and one under the Levern Water will form part of the route of the new main. The tunnels under the Glasgow-Barrhead-Kilmarnock railway and the Levern Water have already been completed.
The tunnel at Ibrox, which is the biggest of the four, was constructed out for the Caledonia Water Alliance by Doncaster-based HB Tunnelling.
The hydraulically-operated TBM worked 24-7 and completed its breakthrough when the cutting head emerged at a point in Bellahouston Park. Manually operated by a driver at the front, the TBM’s rotating cutting head cut into the earth and rock and the material was transported along a conveyor belt to a skip on the TBM before being removed by crane to the surface.
A team of six people worked on the tunnelling, including a supervisor and banksman.
After the tunnel was installed, 22 sections of water main made from ductile iron were placed inside it, using a crane to lower the pipe sections down and a winch to pull them through the tunnel and into position before they were grouted and sealed.
Scottish Water delivery manager Dominic Flanagan said: “The installation of this particular part of the new water main using the TBM is arguably the highlight of this project so far and we are delighted to have completed it. Everything went well with this very challenging and complex operation.”