The City of Torontoʹs Sewer Use By-law and pollution prevention

In 1998, Toronto City Council approved the proposal made by the Commissioner of Works to end the incineration of biosolids1 at the Ashbridges Bay Sewage Treatment Plant. Biosolids, also known as treated sewage sludge, are a nutrient-rich organic material, resulting from the biological treatment of the sludge generated during the treatment of municipal wastewater. The biosolids were to be used partly for spreading on agricultural land with the remainder used as fertilizer in the form of pellets. This necessitated improvement in the biosolids quality so that they would meet or exceed the provincial guidelines. Based on the provincial guidelines for biosolids and the federal quality requirements for certain organics, a list of 38 parameters called “subject pollutants” was created. These subject pollutants were included in the new Pollution Prevention (P2) planning requirements for facilities. This paper outlines the changes in the new City of Toronto Sewer Use By-law and its P2 planning component. It includes the reduced limits on existing parameters, a new list of subject pollutants including 11 heavy metal and 27 toxic organics, and the mandatory P2 planning requirements. A graphical presentation of P2 planning compliance and the impact of P2 planning on the quality of biosolids is made. The paper reviews those business sectors that must complete P2 plans, experiences with various sectors and P2 implementation. It also discusses lessons learned and changes being made in the P2 requirements for certain sectors. The future direction for this unique mandatory P2 planning requirement is also discussed.