SCOTLAND’S biggest sewer has opened after a £100 million construction project.

Water flows have started to run through the Shieldhall tunnel in the south side of Glasgow, which operators say will lead to less flooding and better environmental conditions for residents.

The three-mile long tunnel was constructed over two years by more than 100 workers using a state-of-the-art tunnel boring machine.

It stretches from Craigton to Queen’s Park via Bellahouston and Pollok parks, and Scottish Water said it will alleviate pressure on the waste water network with 90,000 cubic metres of extra storm water storage.

Environment Secretary Roseanna Cunningham visited the Scottish Water control room yesterday and hailed the project as “extraordinary”.

She said: “The strategic importance of the Shieldhall tunnel as part of the ongoing investment across Glasgow by Scottish Water cannot be understated.

“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.

“Communities across Glasgow will benefit for years to come from this latest extraordinary feat of engineering that lies hidden deep beneath the city.”

The tunnel is the flagship project in Scottish Water’s investment in Glasgow’s waste water infrastructure and will reduce the risk of flooding, particularly in Mount Florida and Giffnock.

Douglas Millican, Scottish Water’s chief executive, said: “We are delighted to have completed the Shieldhall tunnel, which is ... the biggest in well over a century.

“The city’s waste water infrastructure required major improvements to help transform it into a modern, integrated and sustainable system that 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.”