McLoughlin Point Wastewater Treatment Plant outfall Microtunnel

Michels Canada completed a 117m long, 2,121mm diameter tunnel for an outfall at a new wastewater treatment plant.

Michels used a Herrenknecht AVN 1800 microtunnel boring machine (MTBM) to complete a 400 LF single drive of a 25.45m OD lined and coated Permalok steel pipe to provide an ocean outfall for the new wastewater treatment plant. The MTBM was launched from a rock wall shaft below sea level and exited into a rock trench 11m under ocean depth. Mining was completed in granitic rock. Pumps were used to control groundwater inflow of more than 75L per minute in the launch shaft. A Herrenknecht laser guidance system was used. Standard cement grout was installed with a low-pressure pump to fill annulus space.

All work was conducted in a highly confined space. Following the completion of the drive and installation of the bulkhead, an ocean retrieval was conducted to remove the MTBM from the tunnel. Michels is one of the most experienced contractors at successfully executing underwater retrievals of a MTBM.

This project was named the 2019 Canadian Project of the Year at No-Dig North in Calgary, AB