Trenchless Technology

Fall Canada 2018

Trenchless Technology is the premier communications vehicle for the trenchless industry. Through our multiple platforms, readers receive insights into the trenchless industry, as well as keep connected to the latest news, products and projects.

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W W W.T R E N C H L E S S T EC H N O LO GY.C O M/C A N A DA 21 H2S gas concentrations were expected due to high sewer turbulence. In the coming months, crews will commission the new line in advance of handover to the client, months ahead of schedule. To complete the project ahead of schedule, the Ward & Burke team had up to three microtunnel boring ma- chines operating at one time. The team used a combination of two Herren- knecht AVN 1800s, one Herrenknecht AVN 1600 and one Herrenknecht AVN 1500. For long drives and curved drives, Ward & Burke used a VMT SLS LT guid- ance system. In the event that extra power was needed for the longer drives, Ward & Burke installed upward of 20 interjack stations (IJSs), but they were able to keep jacking forces low enough that the IJSs were not employed. Challenges Ground conditions for the Twinning of the East Brampton Trunk Sewer con- sisted primarily of glacial till, which is fairly typical for the Greater Toronto Area. The till consists of a mixture of clays, sands and silts with cobbles, boul- ders and occasional gravels. While the ground itself can be challenging , the GTA-based contactor has a great deal of experience in this type of soil. " We are very familiar with these types of condi- tions," said Grennan. " We were able to maintain low jacking forces over the en- tire job, so the job was very successful from a tunnelling perspective." What did prove to be a challenge was dealing with parties along the project alignment. While verifying utility lo- cations at the north end of the project, the project team found that a 600-mm gas main that feeds a power plant was in direct conflict with the alignment of the new sewer. To remediate the con- flict, a vertical curve was introduced to raise the tunnel path above the gas main, with the gas company requiring 0.6 m of separation between the main and the new sewer. As a result of the change, the revised alignment conflicted with a fibre-optic duct back farther upstream. Because the gravity-fed pipe could not be lower, the utility company had to expose and relocate its infrastructure to allow the tunnel to pass unimpeded. " Dealing with third parties to keep the project moving forward was quite challenging ," Grennan said. " But we were able to get all the stakeholders together and redesign the alignment . The good news is that we were able to find the discrepancies as we were do - ing our due diligence rather than find- ing the conflict with the TBM." Another first on the project was a crossing of Highway 407, a major thoroughfare that is a leased toll road in the project area. Ward & Burke worked with the concessionaire, 407 ETR Concession Co. (Cintra /CPP In- vestment Board/SNC-Lavalin), to as- sure that tunnelling activities did not interfere with roadway operations. Jim Rush is editor of Trenchless Technology Canada .

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