May 7, 2020

The City of Toronto and Enwave Energy Corporation, as co-proponents, have completed an assessment to examine expanding the existing Deep Lake Water Cooling (DLWC) supply. Enwave provides cooling to over 80 buildings in downtown Toronto through its District Energy System.

The City and Enwave operate under an existing Energy Transfer Agreement (ETA) that facilitates the transfer of cooling energy from the City’s drinking water infrastructure into Enwave’s District Energy Supply through heat exchangers.

There is continued growth in demand for cooling Toronto’s downtown core, and Enwave anticipates about 35 per cent increase in its customers’ cooling demands in the near future. There is an opportunity for the City and Enwave to amend the Energy Transfer Agreement and expand the DLWC system to meet the cooling demand in a mutually beneficial way.

Following consultation with the community and key stakeholders, the preferred solution is to expand the DLWC supply. The preferred solution includes the addition of up to two new intakes deep into Lake Ontario at the Island Water Treatment Plant (WTP). Raw water would bypass the WTP and be delivered to the ETS and then the Simcoe Street Cooling Plant to be used as cooling water for Enwave’s District Cooling Loop before being discharged back to the Toronto Harbour.


Notice of Study Completion 2020 September


Executive Summary

DLWC map, please contact Mae Lee at 416-392-8210 or if you need help reading this
Click to enlarge

How the System Works

The City’s Island Water Treatment Plant (Island WTP) draws cold water from three intake pipes that extend deep into Lake Ontario. Before entering the City’s distribution system, the treated water passes through Enwave’s Energy Transfer Station (ETS). There, heat exchangers transfer thermal energy from the district cooling water loop to the cold drinking water. The rechilled cooling water is circulated through a closed loop running throughout downtown to provide cooling to buildings, and then Enwave recycles the heat, returning the warm water to the ETS to repeat the process.

More details are available on Enwave’s website.

Council Direction

December 2019 Toronto City Council Direction

Study Process

Ontario’s Environmental Assessment (EA) program promotes good environmental planning by determining and managing the potential effects of a project prior to implementation. Environmental Assessments identify and consider the potential impacts a project may have on a natural, social, economic, and technical environments.

The assessment has been completed in accordance with the Municipal Class Environmental Assessment (MCEA), Schedule “B” approved planning process under the Environmental Assessment Act.

The process provided members of the public and interested stakeholders with opportunities for input at key stages of the assessment, including an on-line public consultation event that was held on May 21, 2020. The assessment defined the existing problem and opportunity, reviewed potential impacts, evaluated the alternatives and identified the recommended solution.


Recommended Solution

The recommended solution is shown in the Study Area Map, and includes the following:

 – Construction of a fourth intake now and a fifth intake in the future. The new intake pipes would be inter-connected with the three existing deep lake intake pipes at the Island Water Treatment Plant (WTP).
 – Raw water from the new intakes would supply the existing Island WTP and would also bypass the Island WTP and be delivered directly to Enwave’s Energy Transfer Station (ETS) through the construction of a new raw water tunnel – separate from the City’s drinking water.
 – The cold raw water would pass through new heat exchangers at the ETS and Enwave’s Simcoe Street Cooling Plant before being discharged back into Lake Ontario via modifications to the existing connection to the City’s existing stormwater system.

Personal information received in response to this notice is collected under the authority of Part II.1 of the Environmental Assessment Act and s. 7 and 8 of the City of Toronto Act, 2006 for the purpose of consultation, preparation and submission of a Municipal Class Environmental Assessment (MCEA), the maintenance of an associated project file (which shall be a record maintained for the purpose of being available to the general public), reporting to City Council as required, submission to the Ministry of the Environment, Conservation and Parks (MECP) as required, and the execution of the Deep Lake Water Cooling (DLWC) Expansion project.By submitting information in response to this notice, you consent to the disclosure of this information between (and correspondingly authorize the indirect collection of same by one party obtaining information initially collected by the other) Enwave Energy Corporation and the City of Toronto (including the respective consultants and advisors of each) for the purpose of consultation, preparation and submission of a MCEA, the creation and maintenance of an associated project file which is available to the general public, submission (including disclosure of personal information) to the MECP as required, and the execution of the DLWC Expansion project.Questions about the collection of personal information may be addressed to the contact person noted in this notice.