A GIANT tunnelling machine was lowered into the ground to start digging at Knighton on Wednesday as work began on the third and final stage to upgrade the link carrying drinking water from the Elan Valley reservoirs to the city of Birmingham.

The three-metre diameter tunnelling machine began work on the final tunnel in Severn Trent Water’s Birmingham Resilience Project modernising one of STW’s most significant supply pipelines, the Elan Valley Aqueduct (EVA) which has been bringing clean water to the homes and businesses of Birmingham and the surrounding area for more than 100 years.

After all those years of service, the need for regular maintenance and refurbishment is becoming ever more frequent and so the time has come to provide extra support for the EVA to make sure that it can continue to provide service for another 100 years.

“At the moment, the EVA is the sole source of supply into Birmingham, and storage at our treatment works at Frankley means we can only turn it off for a few days at a time.

“Obviously as we think to the next 5,10 or 25 years, the kind of maintenance that the aqueduct will need will take longer than that. so we are proposing to build a new pipe from Lickhill, near Stourport-on-Severn, 25km into our existing treatment works in Birmingham.

“At an investment of over £250million, this is the biggest engineering project that Severn Trent has ever embarked on. Once in place, the new pipe will allow us to turn off the EVA for up to 50 days every other year, meaning we can give the aqueduct the care and attention it needs, without affecting the water supply for over a million customers. But even if all goes well with the project, the new pipe won’t be ready for use until 2019. Our checks on the existing aqueduct show that in three places, there was work that we’d rather do before then, but as we can’t shut down the pipe, we’ve had to come up with other solutions,” said Sarah-Jayne O’Kane for Severn Trent Water.

Three new pipes are being built, then connected at either end to effectively form bypasses of parts of the aqueduct.

So far, the two pipes at Bleddfa and Nantmel are complete and the third in Knighton is starting now.