Ontario Line

Potential effects and mitigation measures

Potential effects:

• Disturbance or displacement of wildlife.
• Removal of/damage to trees, terrestrial vegetation and wildlife habitat, including migratory breeding bird habitat.
• Erosion and sedimentation

Mitigation measures:

• Identify opportunities to promote pollinator species and habitat in accordance with the Metrolinx Vegetation Guideline (2020) (e.g., this may include planting or seeding native flowering plants in temporarily disturbed areas).
• Tree and vegetation removal will be kept to a minimum and limited to within the construction footprint.
• Tree and vegetation removal compensation will be provided in accordance with the Metrolinx Vegetation Guideline (2020).
• Temporarily disturbed areas will be restored/re-vegetated.
• Erosion and sediment control measures will be implemented.
• Prior to early works activities, species-specific surveys will be completed to avoid or minimize potential impacts and meet all Species at Risk regulatory requirements.
• Tree Protection Zones will be clearly staked prior to construction using barriers in accordance with local by-law requirements.

Read more - Appendix A1 - Natural Environment Report

Potential effects and mitigation measures

Potential effects:

• Temporary increase in air pollution and odour (e.g., diesel combustion products such as NO2) as a result of construction vehicle emissions and increased traffic due to potential congestion associated with construction activities.
• Temporary increase in dust, silica and airborne particulate matter resulting from earthworks, material handling and transfer, demolition and construction activities.  

Mitigation measures:

• Construction equipment will comply with all applicable regulatory emission standards.
• Contain (e.g., tarp) sources of dust such as soil stockpiles as required.
• Full or partial enclosure of demolition and other activities where possible and necessary.
• Use dust suppressants such as water as required.
• Implement on-site air quality monitoring and apply threshold “Action Level” triggers for implementation of specific and increasing intensity mitigation activities linked to specific construction activities.
• Develop a plan to manage air quality throughout construction to ensure consistent attention to mitigation of dust and particulates from the construction site.
• Develop a communications protocol which includes timely resolution of complaints.

Read more - Appendix A2 - Air Quality Report

Potential effects and mitigation measures

Construction noise

Potential effects:

• Without mitigation, potential for noise level criteria exceedances at a number of nearby sensitive receivers (see Key Findings for details).

Mitigation measures:

• Establish and apply project-specific construction noise criteria/exposure limit.
• Use construction equipment compliant with noise level specifications in the Ministry of the Environment, Conservation and Parks’ NPC-115 and NPC-118 guidelines.
• Keep equipment in good working order and operate with effective muffling devices.
• Evaluate acoustic equipment enclosures for equipment such as compressors and generators.
• Use of upgraded construction hoarding (considering requirements from CSA Z107.9 for noise barriers) between construction equipment and noise sensitive receivers.
• Use of localized noise barriers for specific equipment and operations, including on corridor construction works where applicable.
• Reduce simultaneous operation of equipment where possible.
• Implement a no idling policy on site (unless necessary for equipment operation).
• Restrict construction hours where possible:
  
  • perform construction during daytime hours where possible;
  • if nighttime construction is necessary, activities with the highest noise levels should be conducted during daytime periods; and
  • if construction will occur outside of normal daytime hours, inform local residents of type of construction and expected duration prior to commencing work.
• Undertake noise monitoring and regular reporting throughout the construction phase as required.

Develop a communications protocol for providing advance construction and vibration impact notices and addressing public complaints in a timely manner.

Construction vibration

Potential effects:

• Without mitigation, potential for vibration level criteria exceedances at a number of nearby sensitive receivers (see Key Findings for details).

Mitigation measures:

• Utilize equipment with low vibration emissions where possible.
• Conduct off-site construction of components away from sensitive areas where possible.
• Operate construction equipment on lower vibration settings where available.
• Provide smooth surfaces for trucks to travel.
• Maximize distance between equipment and sensitive receivers.
• Restrict construction hours where possible:
  • perform construction during daytime hours where possible. If nighttime construction is necessary, the activities with the highest vibration levels should be conducted during daytime periods; and
  • if construction will occur outside of normal daytime hours, inform local residents in advance, describing type of construction and expected duration.
• Use alternative construction methods and/or equipment with lower vibration emissions or power settings, where City of Toronto prohibited limits are predicted to be exceeded.
• Conduct monitoring and pre-construction inspections in accordance with City of Toronto Bylaw 514 as required.
• Develop a communications protocol for providing advance construction noise and vibration impact notices and addressing public complaints in a timely manner

Operational noise and vibration associated with increased GO service levels as well as planned Ontario Line operations in the Lakeshore East Joint Corridor are assessed in the Lakeshore East Joint Corridor Noise and Vibration Operations Report included in Appendix C of this Draft Lakeshore East Joint Corridor Early Works Report.  

Read more - Appendix A3 - Noise and Vibration Report

Potential effects and mitigation measures

Potential effects:

• Potential vibration impacts are anticipated to the building at 400 Carlaw Avenue, Queen Street East – Riverside Heritage Conservation District, 6, 8 and 10 Paisley Avenue, Riverdale Heritage Conservation District, and 15 and 17 Tiverton Avenue.
• Encroachment into the Riverdale Heritage Conservation District, 6, 8 and 10 Paisley Avenue, and the DeGrassi Streetscape between Queen Street East and Wardell Street.
• Modifications to the Queen Street East subway may result in direct impact to the Heritage Toronto Plaque located on the sidewalk on the north side of the structure.

Mitigation measures:

• Document (review and establish) the structural condition of the affected buildings to determine if they are vulnerable to vibration impacts from early works.
• Establish vibration limits based on structural conditions, founding soil conditions and type of construction vibration to ensure no damage to heritage structures.
• Implement vibration mitigation measures on the construction site and/or at the building.
• Monitor vibration during construction using seismographs, with notification by audible and/or visual alarms when limits are approached or exceeded.
• Consult with City of Toronto’s Heritage Planning as planning progresses:
  • regarding any physical impact to the Heritage Conservation District, including, if required, the demolition of the non-contributing building of 240 and 242 First Avenue, in order to determine and obtain any approval or permits required, and restoration of vegetative elements;
  • regarding any physical impact to the properties in order to determine and obtain any approval or permits required; and
  • regarding any physical impact to the streetscape and its heritage attributes (i.e. historical plaques) in order to determine and obtain any approval or permits required.
• If removal/relocation of the Heritage Toronto Plaque near the Queen Street East subway can be avoided during early works construction:
  • mark the plaque on detailed design drawings as “to be retained: implement protection measures prior to construction”; and
  • install protection measures such as box or fence hoarding, prior to construction.
• If avoidance of the Heritage Toronto Plaque during early works construction is not feasible and removal/relocation is required:
  • mark the plaque on the detailed design drawings as “remove prior to construction, store, reinstate post-construction”;
  • determine an appropriate removal plan and storage location and remove plaque prior to construction; and
  • reinstate plaque near the bridge postconstruction, preferably in the same location as pre-removal.

Read more - Appendix A4 - Heritage Report

Potential effects and mitigation measures

Potential effects:

• There may be impacts to Eastern Avenue, Queen Street East, Dundas Street East, Carlaw Avenue and Logan Avenue in an effort to keep construction traffic off local roads the community relies on. These impacts could include temporary lane restrictions/closures and construction vehicle traffic causing impacts to traffic.
• Travel time delays for existing transit routes (i.e., TTC bus routes #72 Pape and #143 Downtown/Beach Express and streetcar routes #301 Queen Blue Night, #501 Queen, and #503 Kingston) due to potential lane restrictions and construction vehicle traffic.
• Potential realignment of the existing sidewalks along Queen Street East, Dundas Street East, and Logan Avenue could lead to increased walking distances.
• Potential realignment of the existing on-street bike lanes along Dundas Street East and Logan Avenue.
• Temporary full or partial closure of existing rail tracks may cause temporary reductions or delays of typical rail services

Mitigation measures:

• Develop and implement a transit and traffic management plan as planning progresses.
• Consider scheduling early works activities during off-peak periods and weekends to minimize disruptions to traffic during the critical peak hours.
• Issue notifications and advisory signage to alert traffic and transit users of any upcoming road closures and disruptions as required.
• Coordinate with the City of Toronto to provide pedestrians and cyclists with safe, accessible, and continuous routes during early works activities.
• Consult and coordinate with the City of Toronto to ensure any modifications to pedestrian crossing distances at signalized intersections are reflected in revised pedestrian clearance timing.
• Consult with rail companies (i.e., Canadian National Railway, Canadian Pacific Railway, and VIA Rail) that operate along the rail corridor to assess how track closures would impact their service and coordinate temporary schedules to accommodate all rail services on the open tracks.

Read more - Appendix A5 - Traffic and Transportation Report

Potential effects and mitigation measures

Potential effects:

• Potential for disturbance of shallow and deeply buried archaeological resources due to Lakeshore East Joint Corridor early works activities.

Mitigation measures:

• Complete additional archaeological assessment(s) where required as early as possible and in advance of any ground disturbance.
• If archaeological materials are encountered (or suspected) during early works activities, all work will stop. The site will be protected from impact and additional assessment will be undertaken.

Potential effects and mitigation measures

Potential effects:

• Potential impact on flooding conditions in the Don River floodplain.
• Potential flooding impacts on site during construction.
• Potential change in stormwater quantity and quality due to potential erosion of exposed soil and increased sediment loading which may impact receiving water bodies and/or municipal stormwater drainage system.

Mitigation measures:

• Floodplain impact assessment will be conducted during detailed design following Toronto and Region Conservation Authority (TRCA) guidelines once relevant design information is available.
• Develop a flood contingency plan with specific measures for any proposed work or temporary laydown and staging areas in the Don River floodplain, as project planning progresses.
• Develop the overall stormwater quality and quantity control strategy in accordance with all relevant municipal, provincial, and federal requirements.
• Develop a stormwater management plan and an erosion and sediment control plan, as project planning progresses.
• The following stormwater management best practices will be considered and implemented as required:
  
  • reduce amount of exposed soil;
  • install sediment control measures before grading/land alterations begin;
  • sequence early works activities;
  • protect storm drain inlets to filter out debris; and
  • stabilize all exposed soil areas as soon as land alterations are complete.
• If required, obtain a Municipal Discharge Permit (City of Toronto Private Water Discharge Permit/Agreement) to manage excess surface water/stormwater.
• TRCA, Waterfront Toronto, and City of Toronto will be consulted to avoid potential infrastructure conflicts and impacts to adjacent flood protection measures/ initiatives.

Potential effects and mitigations

Potential effects:

• Potential for disruption to adjacent lands to accommodate early works activities.
• Nuisance effects (i.e., dust, noise and vibration) and potential for light trespass, glare and light pollution effects from early works activities.
• Visual effects from permanent public-facing structures and early works activities.
• Permanent and temporary property acquisition (property requirements will be confirmed as project planning progresses).
• Temporary or permanent relocation or removal of streetscaping materials, furniture, public art piece(s) and landscaping in the public realm.

Mitigation measures:

• Maintain regular (existing) access to businesses during working hours where feasible. Where regular access cannot be maintained, alternative access and signage will be provided.
• Construction lighting will be controlled or mitigated to avoid unnecessary and obtrusive light with respect to adjoining residents, communities and/or businesses.
• Develop an air quality management plan to mitigate potential impacts of dust during early works activities (see Air Quality for further detail and more mitigation measures).
• Develop a plan to manage noise and vibration during early works activities (see Noise & Vibration for further detail and more mitigation measures).
• Reduce the visual effects of bridges, retaining walls and other permanent public facing structures by selecting appropriate building materials and architectural design.
• Provide screened enclosures along early works site boundaries where necessary.
• Provide temporary lighting and wayfinding signage around early works sites as required.
• Provide clearly marked pedestrian and cyclist detours where required.
• Following completion of early works, impacted lands will be restored to current City of Toronto standards wherever feasible.

Potential effects and mitigation Measures

Potential effects

Groundwater

• Settlement of structures in the Zone of Influence* (ZOI) due to construction dewatering.
• Encounter previously contaminated groundwater during early works activities (e.g., dewatering).
• Construction dewatering may impact groundwater dependent natural features (i.e., Don River as a result of decreases in groundwater discharge).

Soil

• Displacement of soils as a result of early works activities may result in ground movement and settlement.
• Early works activities (e.g., excavation) could expose and/or result in the spreading of contaminated materials.

*The Zone of Influence refers to the area where groundwater levels will be lowered due to dewatering.

Mitigation measures:

Groundwater

• As project planning progresses, determine water taking quantities, quality, and resultant dewatering ZOI through a site-specific hydrogeological investigation, construction dewatering assessment and groundwater management plan as required.
• Completion of pre-construction inspections of structures in the dewatering ZOI and implementation of a detailed settlement monitoring program, complete with settlement triggers that result in changes to the dewatering program if surpassed, to mitigate potential settlement impacts to existing structures if anticipated.
• Adhere to source water protection best management practices, where necessary, including the development of a salt management plan and a plan for handling and storage of chemicals.
• Develop and implement remedial action plans, risk assessment and risk mitigation plans for encountering contaminated groundwater.

Soil

• Complete a detailed settlement analysis as project planning progresses.
• Employ excavation support systems as required and/or implement appropriate ground treatment to reduce the risk of ground loss during early works activities.
• Develop management plans for handling, management and disposal of excavated material.
• Develop and implement remedial action plans, risk assessment and risk mitigation plans for encountering contaminated soil.