Digging deep for our water - incredible machine completes work on Mid Wales tunnel
It has taken six months but a specialist digging machine has finally finished a multi-million pound tunnel in Mid Wales to bring water to the region.
Workers have been busy using a specialist boring machine to to create the first of three tunnels which will reinforce water supplies to Birmingham and the surrounding area from the Elan Valley Aqueduct (EVA) in Mid Wales.
The pipes are being built at three locations, with Bleddfa complete, and the workers now moving on to Nantmel, before the final tunnel at Knighton.
The work is being carried out to provide alternative pipes to take water to Birmingham so that maintenance work can take place on the Elan Valley Aqueduct, which has been providing water for Birmingham and the surrounding area for more than 100 years.
Paul Dennison, programme manager for Severn Trent, said the work is vital because the EVA is the only water supply for Birmingham.
He said: "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 for maintenance.
"To allow us to turn it off for longer periods, an alternative water supply for the city is being built. Work began this month on a new pipeline from Lickhill, near Stourport-on-Severn, 25km into the existing water treatment works in Birmingham.
"However, our checks on the existing aqueduct show that in three places, there is work that we'd rather do before the new pipeline is completed. As we can't shut down the aqueduct, we've had to come up with alternative solutions."
The three new tunnels are being built then connected at either end to bypass sections of the existing aqueduct.
Each of the multi-million pound projects is huge in its own right, and the machine used to cut the new tunnels is more than three metres in diameter.
Mr Dennison said they have now been able to transfer the supply of water from the 100 year old aqueduct to the new pipe.
He said: "We've been working at Bleddfa since October 2015 and a launch ceremony was held in May 2016 to celebrate the arrival and launch of the tunnel boring machine which then spent the next six months underground digging the 1.8km long tunnel.
"The machine broke out successfully in December 2016 – right on target, completing the first tunnel.
"The last few weeks have been a busy time for us as we've been working on the transfer of flows from the 100 year old aqueduct at Bleddfa into the newly constructed tunnel. We planned the work to coincide with a scheduled shut-down of the EVA, when flow through the aqueduct is suspended for five days to allow inspection and maintenance."
Mr Dennison said it had not been a simple process to switch the supply.
He said: "The new tunnel was flooded by removing the barriers from each end, resulting in the flow being shared between the old aqueduct and the new tunnel. The water was diverted into the new tunnel by placing a series of specially shaped concrete blocks into the aqueduct gradually turning the flows from the old to the new.
"The roof slab sections have now been replaced and we have begun backfilling the two working areas. This is a fantastic achievement by all the team to complete the flow transfer in such a short space of time – just three days. We expect everything to be fully back to normal by the end of August at our site at Bleddfa village, and a month later at our site near Monaughty."
All the tunnelling equipment from Bleddfa has now been transferred to the second site at Nantmel, where the tunnel boring machine is being prepared for its re-launch this month to start work on tunnel number two.
