Early breakthrough in British Columbia3 December 2010
A second TBM has achieved breakthrough at Seymour Capilano Water Filtration Project, three months ahead of the revised schedule. The 3.8m diameter Robbins TBMs have spent two years tunnelling, excluding an 18-month suspension due to a dispute over ground conditions with the original contractor. The second contractor was the Seymour Capilano Partnership (SCP) JV consisting of Frontier-Kemper Constructors, Aecon Constructors and JF Shea.
Metro Vancouver required the construction of twin 7.2km tunnels through difficult granitic and metavolcanic rock at rates reaching 29m per day. Overburden reached 600m at maximum. Faulting and shear zones were encountered and overcome with a ground support program.
Ground varied from Class I to Class V with rock left bare for the former but supported by rock bolts, wire mesh and channel straps for the latter. Steel sets were also used every 760mm in poor rock conditions.
“I think we’ve proven here that you can tunnel through the hard granitic rock of British Columbia, even with all its quirks and stress releases. We’ve shown that this is an effective alternative to drill and blast,” said Serge Moalli, project manager of Frontier-Kemper.
The breakthrough struck the first tunnel at an angle at the intended location for a chamber to facilitate drilling of the 270m deep Capilano shaft, which will take two years in total.
The tunnels are intended to transfer either raw or treated water to a new filtration plant. When finished, it will clean 1.8bn litres of water per day to federal standards for drinking water.
“We are quite pleased with the breakthrough. The success of this project can be attributed to having an excellent crew of knowledgeable people, good pre-planning of the work and very good TBMs,” Moalli added.