One of the three Roadheaders that will be boring through the limestone under Centretown.
The developers of the LRT’s downtown Confederation Line have a lot of dirt on their hands. And they aren’t sure what they’re going to do with it.
Tunnel construction for the light-rail transit megaproject began on Oct. 11, with Mayor Jim Watson hammering one of the last parts of the “Roadheader” machine that will be boring through the limestone under Centretown for at least the next two years.
Roger Schmidt, the LRT’s technical director, says that for the first phase of the project, dirt and crushed stone will come out of the tunnel’s west portal, located near the corner of Bronson Avenue and Albert Street. Later, it will have to be removed from the “central shaft” at Kent and Queen streets, where another Roadheader excavator will start. After that, a third Roadheader will be starting around the University of Ottawa.
But during a technical briefing at the start of the project, Schmidt said the city still wasn’t sure where the dirt was going to go.
“We’re assessing options as to what is to be done with that, and we have a number of things we’re considering.”
Background information provided by the LRT consortium says each Roadheader will move three to five truckloads of dirt per hour, and progress should be about three metres of tunnel per day.
With three Roadheaders operating, this could mean 15 dirt-filled dump trucks roving the streets at any given time.
“Portal construction and excavation will be noisy and will produce dust as well as debris,” the documents states. “
But Schmidt says residents may not notice the 135-tonne machine clawing away dirt and rocks 15 metres below them.
“The noise the Roadheader makes is like a low rumble, but it’s going to be almost imperceptible to people outside the tunnel.”
He also says filters will clean the air before it’s fanned out to the street, and sound dampeners will be used on all the exhaust fans.
The document also notes that the noisiest activities will be scheduled during the day, “when noise sensitivity is at its lowest,” and supervisors will monitor vibrations at surface level.
Christine Leadman, executive director of the Bank Street BIA, says she hasn’t worked out a plan with the city yet, but is sure that “any project of this scale will have an impact across the board.”
Consortium spokesperson Kathryn Keyes says officials will provide updates to the city, in terms of road closures and traffic changes, including expected shutdowns of the transitway.