The City of Toronto is undertaking an ambitious project aimed at rehabilitating midtown’s Rosehill Reservoir, the oldest and largest of 11 such facilities in the city.
Originally built in 1873 as an open-topped reservoir, the facility was expanded and the structure covered in 1966. The concrete structure has not been upgraded since.
A condition assessment conducted in 2014 confirmed the structure requires rehabilitation to ensure it remains waterproof and structurally sound. The city said these upgrades will help to ensure the reservoir's structural integrity, extend its service life and bring the infrastructure to a state of good repair.
"This is essential to ensure safe and secure drinking water," the city said in a flyer to local residents.
The reservoir stores treated drinking water and distributes it to neighbourhoods across the city. The structure is covered with a green roof that forms part of David A. Balfour Park.
That roof will be reinstated once construction is complete.
The project is being undertaken by a city team that includes Engineering & Construction Services, Toronto Water, the Public Consultation Unit, Heritage Preservation Services, Parks, Forestry and Recreation, and the Toronto and Region Conservation Authority.
The consultant team consists of Associated Engineering, Brodie & Associates Landscape Architects and Brown & Storey Architects, acting as heritage consultants.
William Fernandes, the director of water treatment and supply for Toronto Water, said the project is part of a reservoir rehabilitation program that is being undertaken "in a staggered manner."
His division delivers drinking water, collect and treats wastewater and provides stormwater management services.
Currently, waterproofing and structure rehabilitation work is underway at a reservoir near St. Clair Avenue West and Spadina Road.
"One half of the reservoir is in service," Fernandes said. "The second half is now being rehabilitated."
Construction is scheduled for completion in fall 2019.
Fernandes said engineering design has been completed on the Rosehill Reservoir project, which is currently being tendered. A contract is expected to be awarded by the first quarter of 2018.
The estimated project cost is $35 million.
Contractors were prequalified to bid the project, Fernandes said.
Construction will involve the rehabilitation of interior and exterior concrete and refurbishment of expansion joints; upgrades to improve reservoir access for operation and maintenance; and replacement of the reservoir roof exterior waterproofing membrane system.
The project also includes the rehabilitation of the reservoir access house and valve house; replacement and repair of process piping and valves; replacement of soil over the reservoir roof and improvement of surface drainage; rehabilitation of perimeter storm drainage and perimeter footing drain systems; and reinstatement of the reservoir's green roof and park facilities.
Construction is scheduled to get underway in the second quarter of 2018 and be completed by the end of 2021.
Fernandes said the project is not expected to pose any major challenges from a construction perspective. However, some dust and noise is inevitable.
The contractor will be responsible for ensuring the work area is kept clean with weekly sweeping and wetting of the site and adjacent streets.
"I think the big challenge will be traffic," Fernandes said.
Trucks will be required to dispose of soil over the reservoir's roof, which has a high-clay content and is not free-draining. To improve site drainage, soil will be replaced with new, well-draining soil.
Trucks will be required to follow a route from the reservoir to the disposal site that is designed to minimize disturbances to the local community.
Plans for the project were unveiled at a public meeting in mid-September. The city has been working closely with key stakeholders, among them local city councillors and residents' groups.
"I think communication has been the biggest part of this project," Fernandes said, referring to the process of community engagement that has been adopted for the project.