Rebecca Sanitary Trunk Sewer

Highlighted as part of the Region’s Intensification Study, the Rebecca Trunk Wastewater Main project addressed 4.2km of trunk wastewater main from Trafalgar Road and Lawson Avenue to the Oakville SW WWTP in the Town of Oakville. The microtunnel project is comprised of 2.5 km of 1,200mm and 1.7 km of 1,350mm ID pipe.

As the project was completed in a highly congested and affluent area, removing roads and mature trees was not a viable option. The final design showcases the abilities of the microtunnelling method in conjunction with proper planning, design, construction and management. The longest tunnelling drive at 627m incorporated four curves and snaked through an installed 3.0m x 2.4m box culvert grouted with 3.0MPa strength concrete under 14 Mile Creek.

The Rebecca Trunk Wastewater Main project included a total of nine microtunnel drives varying in length from 181 meters to 627 meters. Eight of the drives were curved or composite curves based upon requirements to:

• limit impacts to existing utilities;
• protect trees and existing structures;
• minimize easement requirements;
• maximize clearance beneath environmentally-sensitive creeks; and
• connect locations required to remove existing pumping stations offline.

The nine tunnel drives included 15 total curves, including four curves on one drive which was 626m in length.

The bridge crossing of Sixteen Mile Creek was a significant design challenge to be overcome by sharing the underside of the bridge with existing utilities and suspending the sewer.