Big Becky breaks down

But Ontario Power Generation says the breakdown shouldnÂ’t further delay completion of the project, which is already four years behind schedule.

The latest problem has cropped up in “Big Becky”, the machine that is chewing out the 14-metre-diameter tunnel that will increase the flow of water through the Niagara generating station.

“There’s a beam that runs through the centre of the boring machine,” said OPG spokesman Ted Gruetzner in an interview.

“Workers discovered a crack in it so they shut the thing down so they could make the repairs.”

They are welding supports onto the cracked beam to reinforce it, he said.

Gruetzner said the break should not further push back the over-all schedule. Other maintenance work had already been planned, and would have forced the machine to shut down in the coming weeks.

That maintenance works now been moved up to coincide with the emergency repairs, he said, so the later shutdown wonÂ’t be needed.

“They should be back up and running by Christmas time,” he said.

Big Becky, which started boring in 2006, was supposed to have completed the job by 2009.

But unexpected geological conditions caused delays and forced the tunnel to take a longer route than planned.

The cost of the project has risen to $1.6 billion from the original estimate of $985 million.

The contractor for the project, the Austrian company Strabag AG, was deemed not responsible for the unexpected rock conditions so the cost overrun is being borne by OPG.

Gruetzner said the tunnel has now progressed 9.1 kilometres, and OPG hopes it will break through the final wall of rock above the falls in the first quarter of the New Year.

A coffer dam has already been constructed to keep the area dry when big Becky emerges.

Although the boring will be completed early in the New Year, the project as a whole wonÂ’t be finished until 2013, as the rough tunnel must be lined before it can be used.

The increased water flow through the tunnel will boost NiagaraÂ’s electricity output by 1.6 terawatt hours a year. A terawatt hour is one billion kilowatt hours. OntarioÂ’s total demand in 2009 was 139 terawatt hours.