Background
The City of Toronto's Environmental Assessment (EA) to establish preferred alternatives for meeting future wastewater treatment needs within the Ashbridges Bay Treatment Plant (ABTP) service area was completed in 1999, and approved by the Ministry of the Environment (MoE) in 2008. In accordance with the conditions of approval from MoE, the City is now implementing the works approved by MoE. As the first stage of implementation, the City used a 'Schedule B' Municipal Class Environmental Assessment process (Class EA) to determine the most appropriate technology for disinfecting the effluent from the plant before it enters Lake Ontario. This EA has now been completed and submitted to MoE for approval.
More information on the historical background of the original ABTP EA process is found here.
What improvements will be made, and why are they necessary?
Ashbridges Bay Treatment Plant is the largest of Toronto's four wastewater treatment plants. Ashbridges Bay is located in Toronto's east end, at 9 Leslie Street.
Wastewater is the mixture of liquid and solid materials that residents and businesses flush down toilets and empty down sinks and drains. This material flows through a network of pipes that make up the City's sewer system and enters the wastewater treatment plant. Here, the wastewater is treated before it is released through an outfall pipe into Lake Ontario. During heavy rainfall or snowmelt, large amounts of stormwater combine with sanitary sewage in older areas of Toronto that are serviced by combined sewers. Those high flows impact the City's wastewater treatment plants and cause the system to overload (also known as "bypass"). The result is that untreated sanitary sewage discharges into Lake Ontario.
Works that will be implemented in accordance with approvals already received from the Ministry of the Environment (MoE) include a new effluent disinfection system, a new outfall pipe for disposing effluent in the lake, and a new pumping station at the plant, if the disinfection system and outfall pipe require one.
These improvements will ensure all discharges and emissions meet or better all applicable environmental standards, eliminate the need for existing seawall gates in the lake, and maximize protection of fish, aquatic habitats, waterfowl, vegetation and wildlife.
What is Disinfection?
The first improvement to be implemented is a new disinfection system. Disinfection is an essential last step in wastewater treatment before the effluent enters Lake Ontario. Disinfection kills any microscopic pathogens remaining in the effluent after primary and secondary treatment.
The original ABTP EA identified ultraviolet disinfection as the preferred alternative method of disinfection, subject to its applicability to ABTP effluent. Since there have been significant advances in research and technology since this conclusion was reached about 12 years ago, the City recognizes that it is in the best interest of all Torontonians to conduct a new study to review the disinfection methods currently available. This will determine whether UV disinfection is still the best treatment method for both the treated and bypass effluent from the ABTP. The City is therefore currently using a Schedule B Municipal Class Environmental Assessment (Class EA) to determine the most appropriate technology for disinfecting the effluent from the plant before it is discharged.
Get Involved
The public was involved in this Class EA through a public meeting and a steering committee made up of community members.
Notice of Commencement
A Notice of Commencement (PDF) was issued on April 3, 2009.
Public Meeting
The technically preferred alternative method of disinfection and a summary of the information used to inform its selection was presented at a public meeting on December 7, 2009. Materials presented at this meeting are available here:
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Acrobat reader to view PDF files. 
All comments submitted during and after this public meeting were used in finalizing the recommendations of the Project File. Details of this meeting are found in Appendix A of the EA Project File.
Steering Committee
A public steering committee was also involved in this Class EA. The Implementation and Compliance Monitoring Committee (ICMC) will continue to act as a steering committee for future undertakings associated with the original EA. For more information on upcoming meetings, please visit the ICMC web page.
Completion & Project File Report
The Disinfection Class EA study has been completed. A notice indicating this, as well as details of submitting further comments, has been delivered to community members, and appeared in the Beach Mirror on February 25 and March 4, 2010.
The Project File is available for review here, as well as in hard copy at both the Toronto
Reference Library and Beach Library.
Contact Us:
Patricia Halajski
Ashbridges Bay - Approved Undertaking, Community Facilitator's Office
Consumers Road, Suite 201
Toronto, Ontario, M2J 4Z2
Email: abtpea@toronto.ca
Tel: 416-338-1065
