‘Squirrel’ has finished its job of burrowing a hole under the Fraser River between Coquitlam and Surrey.
The massive tunnel boring machine deployed by Metro Vancouver to drill a water supply tunnel to serve the South Fraser area was hauled out of the river last Friday.
That ends the critical stage of the $240-million project, which will double the regional district’s capacity to supply water to the Surrey area and ensure the flow of drinking water can survive an earthquake.
The one-kilometre tunnel is 30 metres below the river bed and was cut between two 60-metre deep vertical shafts.
The tunnel boring machine, dubbed Squirrel, began work in early 2014.
Drilling was halted last October when the machine ran into trouble beneath the river, but resumed in April after repairs to its cutting head.
Crews now have to install a new 2.1-metre diamete welded steel water main in the tunnel and shafts and connect them to the existing water lines. Work is to be finished in the fall of 2016.
“This complex crossing of the Fraser River by a tunnel boring machine under very difficult ground conditions is a major technical achievement,” said Metro utilities committee chair Darrell Mussatto.
The new tunnel is also expected to be more resistant to river scouring, which knocked the old water main offline in 1997 and forced temporary water restrictions in Surrey.
Inside the new water supply tunnel.