Current status

Environmental assessment: approved, February 13, 2008

Project summary

The purpose of the undertaking is to reduce the environmental impacts of the wastewater treatment plant by improving the quality of effluent from the plant.


City of Toronto




Sewage and water

Reference number



Environmental Assessment and Permissions Branch

Project history

Environmental assessment: approved
Date submitted: December 18, 1997
Expiry of public comment period for ministry review: June 25, 2004
Decision date: February 13, 2008

Environmental assessment

The environmental assessment (EA) deals with reducing the environmental impacts of the plant by improving the quality of effluent from the plant. The improvements which received approval include:

  • a larger-capacity outfall pipe extending approximately 3.7 km into Lake Ontario to replace the current 1 km long outfall pipe
  • an ultraviolet (UV) disinfection system which will replace the present chlorine-based disinfection system
  • a new effluent pumping station so the new outfall and UV disinfection system can handle peak flows at the plant


The project was originally initiated as a Class EA project under the Municipal Class EA by Metropolitan Toronto in 1989, but the City of Toronto and members of the public requested that the project be elevated to an individual EA to ensure that the scope and complexity of the issues were addressed. Metropolitan Toronto voluntarily elevated the project to an individual EA in 1991.

The original EA was submitted by Metropolitan Toronto on December 18, 1997. It sought approval to implement measures to expand the wastewater treatment capacity of the ABTP by 2011 and to improve the effectiveness of the plant at reducing the environmental impacts of the wastewater released from the plant. The EA also proposed the continued use of incineration to deal with biosolids until a study was completed to determine the preferred alternatives for managing and disposing of biosolids.

As a result of numerous public concerns regarding the original EA, the City undertook self-directed mediation with concerned groups and members of the public and requested that the government review of the EA be put on hold. Mediation occurred in 1998 and 1999 and resulted in a 92-page mediation agreement signed by stakeholders and submitted to the ministry as an addendum to the EA on November 17, 1999.

The agreement amended the original EA and reduced it to four projects: the three improvements that the ministry is considering for approval at this time and a tertiary treatment system. The ministry determined that it would be inappropriate for the tertiary system to be included as part of any approval of this EA because studies have not been completed to determine the need for tertiary treatment.

The agreement contained a commitment by the City to undertake studies on the ABTP and the City’s other treatment plants. The studies were to focus on ways to reduce direct discharges of untreated wastewater and stormwater during storm events. The agreement also contained provisions to improve the quality of effluent by introducing new sewer use bylaws and pesticide reduction programs. It also included commitments related to the management and disposal of biosolids, although any required Environmental Assessment Act approvals were to be obtained through the Municipal Class EA, not through this EA. These commitments included: shutting down incinerators at the ABTP, constructing a biosolids pelletization plant, and preparing a long-term biosolids management plan.

The government agency review resumed in 2000, but there were a large number of issues requiring resolution. In June 2002, Ministry of the Environment (MOE) and the City reached agreement on what projects or studies would be subject to this EA approval. MOE, the City and other agencies worked to address any outstanding issues.

The MOE completed its review (see notice of completion of review) of the project. The review was available for public and agency comments from April 26, 2004 to June 25, 2004.

The review concluded that the amended EA meets the requirements of the Environmental Assessment Act. The Review also proposed conditions of approval to address issues that were raised by the public and government agencies and reflects the Mediation Agreement.

The Minister has approved the undertaking with conditions, with the concurrence of Cabinet. The City of Toronto may now proceed with the undertaking, subject to the conditions imposed by the Minister and any other permits and approvals that may be required. All comments received during the ministry’s review were taken into consideration prior to a decision being made on the project.