Tunnelling breakthrough on Glasgow water infrastructure improvement scheme

HB Tunnelling has completed work on a 252m long tunnel running under a busy motorway and railway line to form a key part of a new trunk water main for Scottish Water’s multi-million-pound Glasgow Resilience Project.

The Glasgow Resilience Project involves the installation of more than 11.3km of new pipes to connect the Glasgow area’s water network and the system in Ayrshire.

The Caledonia Water Alliance (CWA), made up of Morrison Water Services and Aecom, is delivering the full project.

Working on behalf of CWA, HB Tunnelling has now finished work on the 252m long tunnel from Broomloan Road in the Ibrox area of Glasgow south of the River Clyde, to the north side of Bellahouston Park.

The tunnel boring machine, named Tytana, travelled under the M8 motorway, Paisley Road West and the Glasgow-Ayr railway line before reaching its destination and completing the tunnel drive.

The TBM installed the tunnel at a depth of up to 20m below ground and excavated about 1,311t of rock, including sandstone and mudstone, during the works. The finished tunnel consists of 100 sections of pre-cast concrete pipes, each measuring 2.5m in length, making the total weight of the tunnel about 500t.

The hydraulically operated TBM worked 24/7 and completed its breakthrough when the cutting head emerged within the reception shaft in Bellahouston Park. Manually operated by a driver, 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 working on the tunnelling also included 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.”

Overall, four tunnels will form part of the route of the new main. In addition to one at Ibrox, which is the biggest drive of the four, a tunnel under the Glasgow-Barrhead-Kilmarnock railway and one under the Levern Water have already been completed.

The last tunnel will run under the Paisley Canal railway and White Cart Water.

The aim of the Glasgow Resilience Project is to ensure continuity of water supply for people throughout the Glasgow and Ayrshire areas.

Connecting the networks will provide a two-way water supply between the Milngavie Water Treatment Works (WTW) system, which provides water for more than 700,000 people across much of the Glasgow area, and the Bradan WTW system, which supplies more than 200,000 customers across much of Ayrshire. It will also benefit almost 50,000 customers in East Renfrewshire.

In the event of a disruption to the water supply in either Ayrshire or Glasgow, the new system will allow millions of litres of water to be transferred in either direction, which should then minimise the impact on customers if there is a burst main or other operational issues.

Flanagan said: “This investment in below-ground infrastructure will support the continued development above ground in communities across these areas and will enable them to continue to grow and thrive.”

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.

According to Scottish Water, the design of the new network incorporates carbon reducing construction materials and methods including innovative self-restraining pipe. Solar panels will also offset the power demands at the new Ibrox pumping station, with the new mains using gravity to reduce power use by 60%.

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