The Rosehill Reservoir is the largest of the City of Toronto’s eleven storage reservoirs. It is located in a well-established residential neighbourhood. In 1966, the reservoir was expanded from one cell with a volume of 156 ML to two cells with a total storage volume of 270 ML and subsequently enclosed. A portion of the David A. Balfour Park is located over the roof of the Rosehill Reservoir and is greatly valued by the local community. The original park included various features, many of which have been identified as being of heritage significance, including the Rosehill Garden, various water features, a Centennial monument, and a public washroom building.
The City of Toronto retained Associated Engineering to provide multi-discipline design, construction and post-construction engineering services for a 360º upgrade and rehabilitation of the Rosehill Reservoir and ancillary systems to bring it to a state of good repair and meet all current water storage guidelines. This includes the structural rehabilitation of the Rosehill Reservoir cells, Valve House and Access House, installation of a waterproofing membrane over the reservoir roof, replacement of process mechanical, building mechanical, and electrical systems, and conservation of identified heritage elements. Additionally, computational fluid dynamic (CFD) modeling was utilized to identify opportunities to improve stored water quality by reducing residence time and minimize stagnation via the installation of baffle curtains and modifications to reservoir operation.
To accommodate the reservoir waterproofing membrane replacement and also improve overall site drainage, the soil and park features were removed, providing an opportunity to update the design of the park features while considering protection of the water quality stored below and the integrity of the structure. As such, construction staging, soil and traffic management, stakeholder consultation, community engagement and communication throughout the project stages were key to public acceptance and project success.