Port Lands Pilot Test Program for Don River Renaturalization and Land Redevelopment

As part of its multiyear Port Lands Flood Protection and Enabling Infrastructure (PLFPEI) project, Waterfront Toronto, on behalf of the City of Toronto, will conduct a series of pilot tests to evaluate the performance of innovate technologies for the treatment of soil and groundwater. The broader PLFPEI project will involve excavating a new, re-naturalized channel for the Don River as a flood protection measure. However, 100 years of industrial legacy has left widespread contamination. The pilot tests are therefore intended to develop approaches to manage contamination that will be exposed through the excavation of the new river channel. The pilot tests will assess techniques to manage soil in-place, and to remediate and reuse excavated soil for flood protection measures. These methods could prevent the need for over 200,000 trucks used for importing ‘clean soil’ and exporting contaminated soils to landfill. Several remedial technologies will be assessed (surfactants, in-situ smouldering combustion, ex-situ smouldering combustion, block and adsorb, biodegradation, in-situ geotechnical ground improvements) to evaluate the following benefits: • Risk management through immobilization of contaminants in place, and avoiding the cost and environmental impact of additional excavation. • Soil stabilization through calcification of soil to increase bearing capacity, to enable steeper slope excavations, and to avoid additional excavation resulting from shallow slopes. • Ground improvements to determine primary and secondary settlement and to test strategies to mitigate long term settlement • Pre-excavation remediation to target hot spots of non-aqueous phase liquid (NAPL) and thereby minimize odour issues during excavation, and to minimize excavation water treatment. • Post-excavation remediation to additionally treat soil prior to reuse and avoid disposal and importation of new soil. The pilot project itself will result in the remediation or risk management of 100 m3 of soil, surface water and ground water, as well as the diversion of 200 tonnes of waste from landfill. If successful, the pilot tests will enable the full scale project to achieve the following benefits: • The land made available for use through remediation and risk management will include the Villiers Island Neighbourhood (the island created by the excavation of a new channel for the Don River). Villiers Island will include 35.5 acres of development land with 5.6 million sf of development density, including 4.5 million sf of residential density (4,820 units) and 1.1 million sf of non-residential density. • 29 hectares of naturalized area will be created in the new river valley (wetland and aquatic habitat). An additional 16 hectares of parkland, on Villiers Island and south of the new river channel, will be risk managed. Assuming a contaminated depth of 5m, the volume of parkland soil risk managed will be 800,000 m3. • Approximately 1.2 million m3 of soil will be excavated to create the new river channel. Within the excavation footprint, deeper contaminants over a 200,000 m2 area (or 400,000 m3 volume of material) will likely be risk managed in place. It is estimated that 80% of the excavated soil can be treated for reuse within the Project. • The total soil and groundwater remediated or risk managed will be approximately 2.16 million m3. • Of the soil excavated from the new river valley, Waterfront Toronto expects to divert approximately 1.02 million m3 from landfill. Up to 700,000 m3 will be reused within the project, following pre-excavation and post-excavation remediation approaches. In addition, up to 320,000 m3 of excavated soil may be used in land creation intended to provide flood protection relief along the existing Keating Channel. Furthermore, the project will support the development of a new, livable, mixed-use community that aims to improve climate resiliency. The renaturalization of the Don River will also create new terrestrial and aquatic habitat, and will contribute to the delisting of Toronto as an “Area of Concern” by Environment and Climate Change Canada, and will therefore also contribute to the Remedial Action Plan objectives for water quality and habitat in Lake Ontario. The project also has strong links to the City of Toronto’s Official Plan, its Climate Change Action Plan, and the Waterfront Toronto Sustainability Framework. The net, long-term economic impact of the project will be a positive return on investment that will create an attractive new community in Toronto’s downtown. The project will also protect against the potential loss of human life as a result of a catastrophic flooding at the mouth of the Don River, while mitigating the substantial costs of repairing flood damage. In terms of knowledge sharing, demonstration of viable approaches to remediating, risk managing and enhancing soil stability would offer learnings for future municipal brownfield projects. In addition, Waterfront Toronto has reached out to local colleges and universities to enhance the knowledge exchange from the pilot test program. Waterfront Toronto has also committed to sharing lessons learned with other municipalities through applicable forums, networking and presentations. (Project description from original funding application)