A 53-tonne tunnel boring machine has been safely lowered into place as part of the £7.1million Ross Flood Alleviation Scheme, spearheaded by Herefordshire Council.
The machine is now to start burrowing out a 400m-long tunnel as part of the engineering works.
Tunnel engineers Morgan Est, led by project manager Ken Henderson, carefully steered the machine as it was lowered into place over the underground shaft by a 50 tonne crane on Thursday (January 31).
Now the machine is underground, another nine gantries will need to be lowered into the shaft and this will be done as work on the tunnel progresses. The gantries will be attached to the tunnelling machine, creating a kind of underground "train".
This "train" will have a conveyer belt on it and will remove the earth which is being tunnelled out. This earth will then be used to build a bund on the A40 as part of the flood scheme.
Ken Henderson said: "This is probably one of the smallest tunnel boring machines that are used and it will only be able to progress at 10m to 12m a day because the mixture of sandstone and mudstone in this area is very hard to break through.
"The tunnel follows the line of the river and will have three curves in it which is why we need to use this machine. We will also be lining the tunnel with segments of concrete as we go along and hope to have completed the tunnel by the end of May," he added.
Councillor Brian Wilcox, Herefordshire Council's cabinet member for highways and transportation, said: "The tunnel is one of the most exciting engineering aspects of this project and it is amazing to think this machine will be tunnelling underground for four months before resurfacing again.
"Work is going well on the scheme and we are on target to finish by July this year," he added.
The Ross Flood Alleviation Scheme, funded by DEFRA, came out of discussions in December 2000 when the town centre was hit by serious flooding and has been developed in close consultation with local businesses and interests.
It has been designed to national standards and will protect areas around Greytree Road, Brook End Street, Millpond Street and the Broadmeadows Industrial Estate from flooding by the Rudhall and Chatterley brooks.