The R.C. Harris Water Filtration Plant provides 44% of Toronto’s drinking water supply and remained fully operational during the course of construction. The project involved the construction of a residue management facility to treat backwash water produced in the filtration of the lake water at the plant. Due to the historical significance of the site and existing buildings (a 1930’s era Art-Deco structure), the entire new facility was installed below grade.

Settlement and movement monitoring was a key quality assurance/quality control requirement. Among the many challenges of the 110-week project was the geometry of the site. The project site was located on a 30-degree slope between two existing structures. Earth shoring was installed around the entire perimeter of the project to allow for a 10 m to 12 m deep excavation and bulk excavation of 10,000 truckloads of soil that was barged off-site on Lake Ontario.

A diversion chamber was installed to re-direct flow to the new facility. Through a series of constructed thickeners and settling basins, suspended particulate is then removed and sent to a centrifuge for drying.