Shieldhall Tunnel now operational as Scotland's biggest sewer
Scotland's biggest sewer - the £100m Shieldhall Tunnel which runs under Glasgow - is now operational.
The project took two years to complete and involved 100 workers from around the world.
It is the biggest waste water tunnel in Scotland, with a 3.1 mile (4.8km) underground channel from Craigton to Queen's Park in the south of the city.
Scottish Water hopes the new sewer will improve water quality in the River Clyde and tackle flooding.
Roseanna Cunningham, the environment secretary, performed the official switch-on two years after launching the tunnel's boring machine.
She hailed the feat of engineering as "extraordinary".
"The strategic importance of the Shieldhall Tunnel as part of the ongoing investment across Glasgow by Scottish Water cannot be understated," she said.
"It's a fantastic example of the capital investment programme delivering real long-term benefits for communities to reduce flooding, help deal with the impact of climate change and improve the environment.
"Much of our underground infrastructure for water and waste water dates to the Victorian era when we proudly led the way in introducing massive improvements to deliver positive impact on the health of our communities."
Ms Cunningham added: "Communities across Glasgow will benefit for years to come from this latest extraordinary feat of engineering which lies hidden deep beneath the city."
The tunnel was excavated using a state-of-the-art boring machine (TBM) weighing 1000 tonnes and longer than 14 buses, and named Daisy the Driller by a local schoolboy.
The tunnel will alleviate pressure on the existing waste water network with 90,000 cubic metres of extra storm water storage.
Its completion marks one of the most significant infrastructure projects in the city Glasgow since Victorian times.
Douglas Millican, Scottish Water's chief executive, said: "The city's waste water infrastructure required major improvements to help transform it into a modern, integrated and sustainable system which will improve the environment and biodiversity on the River Clyde and help tackle flooding.
"As the Greater Glasgow area continues to develop, we are modernising our waste water infrastructure to support the needs of both existing and future customers.
"The completion of the Shieldhall Tunnel is a key part of that network modernisation."
A consortium - the Costain VINCI Construction Grand Projets Joint Venture (CVJV) - was set up to deliver the scheme.
Neil Grosset, the project director of Costain, said: "Completing this scheme, one of the most challenging of its kind in history, is testament to the passion, skills and team spirit of everyone involved in the project.
"The Shieldhall Tunnel is infrastructure that will have a huge positive impact, reducing the flooding risk and improving the environment for the people of Glasgow and the River Clyde now and in the future."
- At 4.7 metres (15.5ft) in diameter, the tunnel will be big enough to fit a double-decker bus inside.
- More than 500,000 tonnes of earth, stone, clay and other aggregates have been excavated in its creation.
- Of that, 90% of the excavated material has been or will be recycled.
- The new tunnel will be five times longer than the Clyde Tunnel.
- It will provide 90,000 cubic metres of extra storm water storage - the equivalent of 36 Olympic-sized swimming pools.
- The giant tunnelling drill advanced through the ground at a speed of about 2cm per minute.