Tunnel Business Magazine

AUG 2018

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Page 36 of 43

TUNNELINGONLINE.COM F E A T U R E S T O RY 3 7 TBM: TUNNEL BUSINESS MAGAZINE // AUGUST 2018 the first plan was determined as over bud- get, Robbins contacted the city about open- ing up the bid f to microtunneling," said Jean-Sébastien coux, project engineer for joint venture contractor EBC Inc. "The biggest advantage of was the we were able to reduce the number of shafts. We can mine as long t with a micro- tunneling machine we would have been limited to 300 m at a time." e required just six shafts and a series of launches for the contractor EB JV using a 2.2 m diameter Robbins Dou Digging the Tunnel The Robbins machine was initially launche y 2016. The contractor re- moved and reinstalled the machine on its first two drives, which were successfully bored in non-abrasive dolomite rock rang- ing betwe a UCS. Then the machine was removed and re-launched to start at Shaft 5 in December 2016. "We were about 160 m in when our crew could hear water rushing in from the tunnel face," said Tim Cleary, General "The next thing they knew there was a river flowing through the tunnel, about 20,000 liters per minute," said Cleary. The crew was able to safely evacuate, but the same couldn't be said for the equip- ment. "The tunnel was filled to the spring- line within 40 minutes, and the 18 to 21 m deep, 6 m long x 6 m wide shaft was filled within two hours to about 3 m below the surface." The project was halted for about six we eal con- ducted an investigation of the incident. An ROV was employed to take a look at the conditions of the tunnel and the quality of the water, which was crystal clear with no pebbles. Once it was deter- mined that the site was safe, the water was pumped down in stages to monitor if there was any re ccurred and over the course of a week the tunnel was pumped relatively dry. "We had to gut ving just the shell intact. We rebuilt everything, from all electrics to all hydraulics," said Cleary. EB able to source parts locally and complete the rebuild quickly. "Six weeks after that call the tunnel was pumped out and I had an opportunity to go underground to look at the condition of the equipment; after- wards I made a phone call to go ahead and order parts." The team was familiar with taking the machine apart and removing it from the tunnel, and rebuilt it on the sur- face close to the shaft. "Eleven weeks later we were back up and mining." F d to use ribs and lagging in lieu of rock bolts and channels. "We didn't want to hit fractures," said Cleary. "There were no issues. We av- eraged 21 m per day." Three rotating crews worked in two eight-hour shifts, seven days per week, to finish the tunnel—an increase from the previous schedule of two crews working 18-hour days, 5 days per week. For EBC, the smoothness of the opera- tion was remarkable: "I think the Robbins machine was the equipment we needed f ble to get through the conditions; we proved this. We had different rock conditions and dif- ferent problems, but the job went very well overall, coux. "Our guys worked so hard and we're so proud of them and how we got back up to speed quickly," said Cleary. Breakthrough occurred ember 14, 2017, within the originally scheduled estimate for proj- ect completion. This article was contributed by The Robbins Company . Montreal's latest tunnel project, the 4.2 km long Rue Jarry Tunnel completed in November 2017, will be used to operate in parallel with an existing 50-year old water line. Montreal, one of Canada's oldest cities, is devoting CAD $348 million to upgrading antiquated water and sewer systems in 2018. The EBC/McNally JV celebrate at the completion of Montreal's Rue Jarry Tunnel. The crew overcame a devastating flood to finish the project on time.

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