The Hanlan Feedermain and Mississauga City Center Watermain is considered one of the largest heavy civil water infrastructure projects in Ontario. The project consists of a 4.4km tunnel for a 2400mm diameter watermain which will carry water from Lakeview Water Treatment Plant to the Hanlan Reservoir and the Mississauga City Centre Watermain, a 4.2km tunnel for a 1500mm diameter watermain which will carry water from Hanlan Pumping Station to the Mississauga City Centre core.

The project consisted of an open cut and tunnel works over 10km in length in Georgian Bay Formation. The tunnels included the installation of a 3100mm and 2260mm diameter steel liner, 410m long underneath 26 lanes of highway 401. Multiple tunnels bored from single shafts. Three different TBMs were utilized at the same time. Tunnel ground supports included rock bolts and steel ribs and lagging. 6 shafts in total, 3 shafts supported with secant piles up to 47 meters deep, which required mobilization of the biggest drill rig in Canada. Installation of 2400mm & 1500 CPP. In total there were 10 cast-in-place chambers on the project, with one requiring an existing 2100mm watermain to be suspended while chamber was built around it. The shafts and open-cut works encountered overburden (glacial till) with frequent cobbles and boulders. Groundwater table was observed at depths ranging from 1.5m to 3.5m. The tunnel works encountered weak to medium strong shale bedrock and limestone layers over 100 MPa. Some sections of shale were weathered and fractured, and had groundwater infiltration. One tunnel heading encountered a buried underground river with gravel. Extensive geotechnical monitoring was implemented on the project, including inclinometers at every shaft, surface monitoring points and convergence monitoring points along all tunnel alignments. Real-time fiber-optic monitoring (OSMOS) consisting of optical strands (accuracy +/- .002mm), temperature probes, and biaxial tilt meters were used on multiple existing bridges in the project vicinity. Noise and vibration monitoring was also used at every construction site. Extensive traffic diversions were required for shaft and open cut works. Careful consideration was required due to close proximity to local residence and businesses. The watermains crossed under many existing utilities (gas, sewer, hydro, etc.) and required relocation of watermain and gas mains.