Analysis of Microtunnel Data Confirms Geostrata for a Curved Microtunnel in the City of Brantford

The city of Brantford constructed a curved microtunnel in challenging soil conditions to upgrade the existing Greenwich sanitary trunk sewer (STS) in 2018. The new sewer provides additional capacity for future growth in the downtown core and for a new recreational facility jointly developed by the city, the YMCA, and Laurier University. Identified in the 2014 City of Brantford Master Servicing Plan for sanitary sewers, and subsequently confirmed with the city’s sewer modelling consultant, this project includes upgrades to the existing sanitary trunk sewer between Clarence Street South and the Greenwich Street sewage pumping station. The existing Greenwich sanitary trunk sewer (STS) in the city of Brantford was upgraded to provide additional capacity for future growth in the downtown core. The new sanitary trunk sewer was installed via microtunnel construction on a curved alignment (radius 970 m) and crossing an active rail corridor. The final installed length of microtunnel was 430 m proceeding through mixed-face ground conditions. Robinson Consultants Inc., together with Aldea Engineering Services Ltd., prepared the design for the microtunnel that was subsequently constructed by Ward & Burke Microtunnelling. This paper explores the challenges faced during design and construction, and the innovative solutions developed by the contractor and the project team to successfully complete the project on time and within budget. The paper also evaluates the application of a geotechnical baseline report (GBR) in the form of GBR sheets to establish the contractual ground conditions, and how the actual ground conditions were reflected in the data logs recorded by the microtunnel boring machine (MTBM).