Yonge North Subway Extension

Key findings

• The YNSE Study Area is highly urbanized with limited natural vegetation cover present, associated mainly with the watercourses and parklands.
• The Study Area provides limited wildlife habitat with low connectivity to nearby natural features.
• The Study Area does not feature any provincially or locally significant wetlands or areas of natural and scientific interest.
• The woodlands and valley lands are designated in corresponding official plans as Natural Heritage Systems (NHS), including York Region Official Plan (e.g., Woodland and Greenland System), Richmond Hill Official Plan (e.g., Natural Core and Greenway), City of Markham Official Plan (e.g., Woodland and Greenway 2014) and City of Vaughan Official Plan (e.g., Core Feature).
• Species of Special Concern including Common Nighthawk, Eastern Wood-pewee, Peregrine Falcon, Wood Thrush, Northern Map Turtle, Snapping Turtle, and Monarch; and Species at Risk including Barn Swallow, Chimney Swift, Butternut and Bat species may occur.
• Fish habitat is limited to three watercourses: East Don River, Pomona Creek and German Mills Creek, with all three watercourses providing habitat for warm, cool and coldwater fish communities. Habitat present includes habitat for migration, spawning, feeding and rearing and is generally non-limiting throughout.
• During construction, wildlife disruptions or displacement will be temporary and reduced via appropriate mitigation measures (see Potential Effects & Mitigation Measures).
• Following construction completion, disturbed areas will be restored. Any in-water works will comply with the Federal Fisheries Act.
• During operations, any wildlife disruptions or displacement during maintenance activities will be reduced via appropriate mitigation measures (see Potential Effects & Mitigation Measures).

Potential effects

Construction phase

• Construction Phase Disturbance or displacement of wildlife and reduced habitat connectivity.
• Disturbance of migratory birds and/or nests.
• Potential introduction and spread of invasive species associated with construction activities.
• Removal of/damage to trees and other vegetation.
• Potential impacts to fish and/or fish habitat.
• Risk of contamination as result of spills (e.g. grease, oils, and/or fuel) from equipment use.
• Erosion and sedimentation.

Operational phase

• Operations may cause disturbance or displacement of wildlife during vegetation maintenance activities.
• Operations may cause soil or water contamination as a result of spills (e.g., grease and/or fuel) from equipment use during maintenance activities.

Mitigation measures

Construction phase

• Vegetation removal will be reduced to the greatest extent possible and limited to the construction footprint.
• Restricting construction activities during sensitive timing windows for wildlife (e.g., removal of vegetation outside of the breeding bird period).
• Tree and vegetation removal compensation will be provided in accordance with the Metrolinx Vegetation Guideline (2020).
• A tree removal strategy/Tree Preservation Plan will be developed during detailed design.
• Temporarily disturbed vegetated areas will be restored/re-vegetated.
• All requirements of the Federal Fisheries Act will be met during all phases of construction.
• Erosion and sediment control measures will be implemented to prevent impacts to the natural environment, including aquatic species.
• Prior to commencement of activities, species-specific surveys will be completed to confirm Species At Risk habitat and presence, meeting all Species at Risk regulatory requirements.
• A Spill Prevention and Response Plan will be developed for construction activities.

Operational phase

• Operation maintenance activities will include nest searches and wildlife surveys prior to maintenance work commencing, as required and appropriate measures taken to avoid impacts.
• Refueling at least 30 m from any watercourse or any other surface drainage feature.

Read Appendix B - Natural Environment Existing Conditions and Impact Assessment Report

Key findings

• Land use designations in the study area include residential, mixed-use areas, employment/industrial, intensification (increase in development and population), utilities/transportation, parks/open space/recreation areas, natural heritage system, and Parkway Belt West Plan.
• The Parkway Belt West Plan aims to reserve land for infrastructure such as transit, hydro and electric power facilities.
• The proposed Subway Extension would effectively connect two Urban Growth Centres that have been identified by the Province of Ontario for transit, and transit-supportive development, in an effort to establish “complete communities” where you can live, work and play.
• Segment 1 is comprised of high-density mixed residential uses (within approximately 100 m of Yonge Street), as well as several parks, parkettes, recreation areas and open spaces.
• Segment 2 consists of low and mid-rise apartments and condominiums as well as single-detached homes. Beyond the Yonge Street corridor and north of Royal Orchard Boulevard, this segment of the Study Area consists of low-density residential neighbourhoods. Commercial uses within this segment consist mainly of low-density commercial plazas. There is also a high concentration of parks, recreation areas and open spaces.
• Segment 3 contains primarily low-density residential neighbourhoods, as well as a series of commercial plazas.
• Potential construction impacts include land use and access disruption, nuisance effects from construction activities, potential temporary road closures, and visual effects from construction activities.
• These impacts will be temporary and are anticipated to be reduced or eliminated by implementing appropriate mitigation measures such as providing temporary lighting, wayfinding signs, detours and cues for navigation around the construction site; maintaining access to nearby land uses where feasible; developing communications and complaints protocols; developing Traffic Control and Management Plan(s); and providing a screened enclosure for the development site(s), where required.
• Potential impacts associated with operations include visual impacts from permanent public-facing structures such as Stations, and light pollution associated with the proposed Train Storage Facility.

Potential effects

Construction phase

• Permanent and temporary property acquisition (property requirements will be confirmed as planning and design progress)
• Nuisance effects (e.g., dust, noise and vibration) from construction activities
• Potential for temporary disruption of access to adjacent lands
• Visual effects from construction areas/activities
• Potential for light trespass, glare and light pollution effects

Operational phase

• Visual effects from permanent public-facing structures
• Potential light pollution associated with overnight maintenance and storage activities at the Train Storage Facility location

Mitigation measures

Construction phase

• Confirm specific property requirements during design, and engage in ongoing consultation with affected landowners to identify appropriate site-specific mitigation measures
• Develop a communications protocol to provide notifications to the community, and address complaints in a timely manner.
• Develop an air quality management plan to mitigate potential impacts of dust during construction (see Air Quality for further detail and more mitigation measures).
• Develop a plan to manage noise and vibration during construction (see Noise & Vibration for further detail and more mitigation measures).
• Maintain access to businesses during working hours, where feasible. Where regular access cannot be maintained, provide alternative access and signage.
• Provide clearly marked pedestrian and cyclist detours where required.
• Provide screened enclosures along construction site boundaries where necessary.
• Develop a plan and apply appropriate mitigation measures to reduce the effects of light pollution.

Operational phase

• Reduce visual effects of project structures by considering their location, building materials, architectural design, and surrounding landscape treatments.
• Develop a plan to reduce the effects of light pollution and comply with all local applicable municipal by-laws and Ministry of Transportation practices for lighting in areas near or adjacent to highways and roadways regarding outdoor lighting for both permanent and temporary construction activities, and incorporate industry best practices provided in ANSI/IES RP-8-18 – Recommended Practice for Design and Maintenance of Roadway and Parking Facility Lighting.

Read Appendix C - Socio-Economic and Land Use Existing Conditions and Impact Assessment Report

Key findings

• Most of the Study Area does not retain archaeological potential.
• Areas that retain archaeological potential include a portion of Hendon Park, north of Hendon Avenue; a parking lot located at the southeast corner of Yonge Street and Newton Drive; sections of grassed areas associated with residential properties south of Steeles Avenue East and east of Yonge Street; sections of grassed areas at 7994 and 8000 Yonge Street; and the section of Royal Orchard Park between Bay Thorn Drive and Thorny Brae Drive.
• Where archaeological potential is present and disturbance is anticipated, further archaeological assessment(s) will be completed prior to construction. The assessment(s) may include test pit surveys and deeply buried investigative techniques, such as mechanical topsoil removal, mechanical trenching, and, if required, construction monitoring.

Potential effects

Construction phase

• Potential for disturbance of shallow and deeply buried archaeological resources due to project construction activities.

Operational phase

• No impacts to archaeological resources are anticipated during project operations.

Mitigation measures

Construction phase

• Complete additional archaeological assessment(s) where required as early as possible and in advance of any ground disturbance. Indigenous Community Field Liaisons will be invited to participate in this work and archaeological assessment report(s) will be circulated to Indigenous Nations for review.
• If archaeological materials are encountered (or suspected) during construction activities, all work will stop. The site will be protected from impact and additional assessment will be undertaken.

Operational phase

• No impacts to archaeological resources are anticipated during Project operations, therefore no mitigation is required.

Read Appendix D - Stage 1 Archaeological Assessment Report

Key findings

• A total of 86 heritage properties, including built heritage resources and cultural heritage landscapes were identified within the Study Area.
• Identified heritage properties include:
• Six properties designated under Part IV of the Ontario Heritage Act: 10 Colborne Street 7780 Yonge Street, Robert West House (subject to Ontario Heritage Trust easement) 7788 Yonge Street, George Munroe House 42 Old Yonge Street, William Walton Armstrong House 8038 Yonge Street, Soules Inn 23 Hillsview Drive, David Dunlap Observatory Lands
• Two Heritage Conservation Districts (HCDs) designated under Part V of the Ontario Heritage Act : Thornhill Vaughan HCD (39 properties within the Study Area) Thornhill Markham HCD (15 properties within the Study Area)
• Three listed heritage properties: 5926 Yonge Street, City of Toronto Heritage Register 5 Patricia Avenue, City of Toronto Heritage Register 7951 Yonge Street, Edwardian House, City of Markham Heritage Register
• One Previously Identified Heritage Property 5925 Yonge Street

Potential effects

Construction phase

• No impacts are anticipated to 29 built heritage resources/cultural heritage landscapes.
• Continued avoidance of these properties is recommended.
• Potential indirect impacts: Vibration damage related to the construction of the Project in the vicinity of a built heritage resource or cultural heritage landscape may occur at 43 properties.
• Potential direct impacts: Above-grade Project components are planned within, or adjacent to, 14 built heritage resources/cultural heritage landscapes.
• Vibration damage may also occur at these properties.
• Operational phase
• No impacts to identified BHRs/CHLs are anticipated as a result of project operations.
• Construction phase - where impacts are anticipated due to potential vibration impacts

Mitigation measures

Construction phase - where impacts are anticipated due to potential vibration impacts

• In all cases, avoidance of the built heritage resources or cultural heritage landscapes is the preferred mitigation measure; only where avoidance was determined to not be feasible were mitigation measures prepared.
• Document (review and establish) the structural condition of the affected buildings to determine if they are vulnerable to vibration impacts from construction activities.
• 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, with notification by audible and/or visual alarms when limits are approached or exceeded.

Where a direct impact such as demolition or alteration to a heritage property may occur

• Complete technical studies, which may include Cultural Heritage Evaluation Reports and/or Heritage Impact Assessments for known or potential BHRs/CHLs where potential direct impacts such as demolition or alteration of heritage structures/landscapes may occur, as required.
• These studies will determine cultural heritage value or interest and provide a detailed impact assessment, conservation guidance, and property-specific solutions to mitigate
• Project impacts. Properties requiring such studies will be confirmed as project design progresses and property-specific impacts are identified.
• Consult with the MHSTCI, OHT, municipalities and other stakeholders as required.

Mitigation measures

Operational phase

• No impacts to BHRs/CHLs are anticipated during Project operations, therefore no mitigation is required.

Read Appendix E - Cultural Heritage Report Existing Conditions and Preliminary Impact Assessment Report

Key findings

• Existing air quality in the Study Area is typical of urban areas in southern Ontario, with background benzene, benzo(a)pyrene, fine dust particles, and nitrogen dioxide air concentrations that are attributed to a variety of sources including industry and transportation.
• Without mitigation, project construction activities have the potential to temporarily increase levels of air quality contaminants near the construction sites.
• Mitigation measures such as watering, engine anti-idling policies, stockpile covering, and others are anticipated to reduce or eliminate these potential impacts.
• The Project is expected to improve air quality in the study area due to the reduction of ground traffic.
• Greenhouse gas emissions are anticipated to decrease as commuters are expected to shift from the use of personal vehicles to the new subway extension, a public transit line powered by Ontario’s energy grid which has one of the lowest carbon intensities in the world.

Potential effects

Construction phase

• The project may temporarily increase levels of air quality contaminants near construction sites for the duration of construction.
• Potential air quality effects would be mainly due to construction vehicle emissions, earthworks, material handling and transfer, and construction activities.

Operational phase

• The project is expected to improve air quality in the study area due to the reduction of ground traffic.
• Greenhouse gas emissions are anticipated to decrease as commuters are expected to shift from the use of personal vehicles to the new subway extension.

Mitigation measures

Construction phase

• An air quality management plan will be developed in advance of construction.
• A complaint response protocol will be developed as part of the construction air quality management plan to assist in timely resolution of complaints.
• Frequent watering of construction zones to decrease dust generation.
• Covering stockpiles of loose materials to prevent dust releases.
• Following anti-idling procedures and controlling the amount of simultaneously operating equipment on-site.
• Limiting simultaneous operation of construction fleet equipment where feasible.
• Using construction equipment with lower emissions where feasible.
• Continuous real-time monitoring of dust and other air quality parameters at construction sites to support effective deployment of mitigation measures.

Operations phase

• As the air quality in the Study Area is anticipated to improve, no mitigation measures are required.
• Some localized activities, such as future maintenance activities in the tunnel or at the train storage facility, may potentially require the development and implementation of Air Quality Management Plans to address potential short term localized air quality impacts.

Read Appendix F - Air Quality Existing Conditions and Impact Assessment Report

Key findings

Construction noise

• The impact assessment conservatively assumed that all construction equipment would operate in a small work area closest to each sensitive receiver instead of being spread throughout a given site.
• Without mitigation, construction sound levels are predicted to exceed construction noise criteria at many sensitive receptors* along the alignment.
• To reduce potential impacts, appropriate mitigation measures (see Potential Effects & Mitigation Measures) will be implemented in addition to the development and implementation of a construction noise management plan before construction begins.

Construction vibration

• The impact assessment employed a conservative approach, where construction equipment was assumed to operate at the edge of a given construction site, closest to sensitive receptors.
• Without mitigation, there is the potential to exceed the vibration criteria at receptors located near (within approximately 9m of) the surface construction sites along the alignment.
• Tunneling using the tunnel boring machines is not expected to exceed the construction vibration criteria.
• Tunnelling support activities (such as the potential use of a temporary railway within the tunnels) has the potential to exceed the vibration criteria at some receptors located near the tunnels.
• The potential for exceedances will be reduced by implementing appropriate mitigation measures (see Potential Effects & Mitigation Measures) and through development and implementation of a plan to manage construction vibration before construction begins.

Operational noise

• The operational noise of the subway is predicted to meet the existing pre-project sound levels. Therefore, no mitigation is needed.
• The subway vehicle passby noise is predicted to meet or be below the passby noise criteria at any sensitive receptor along the alignment. Therefore, no mitigation is needed.
• With proven mitigation measures such as noise barriers, the sound levels from all stationary sources (including stations, ventilation equipment, traction power substations, bus terminals, and train storage facility) are predicted to meet or be lower than the applicable criteria at all assessed sensitive receptors along the alignment (see Potential Effects & Mitigation Measures for more details).

Operational vibration

• Using proven and readily available mitigation measures, ground-borne vibration and ground-borne noise from subway operations are predicted to meet or be lower than the applicable criteria at all sensitive receptors along the alignment (see Potential Effects & Mitigation Measures for more details).
• As detailed design progresses, more detailed studies, including in-field testing, will be completed to define specific vibration control measures.

Operational noise and vibration criteria

Trains

• The noise and vibration criteria for the trains are provided by protocols provided by the Ministry of the Environment, Conservation and Parks.
• As there are no provincial requirements or standards for ground-borne noise, the criteria from the US Federal Transit Administration are used, similar to other recently completed transit projects. Noise and vibration mitigation will be investigated and implemented if a project is predicted to exceed any of the following criteria:

Stationary facilities

The train storage facility (TSF) and facilities such as stations (which include ventilation equipment), traction power substations and bus terminals were assessed in accordance with the Ministry of Environment, Conservation and Parks, Environmental Noise Guideline - Stationary and Transportation Sources - Approval and Planning (NPC-300). Noise and vibration mitigation will be investigated and implemented if a project is predicted to exceed any of the following criteria:

Noise and vibration terminology

Ambient Noise and Vibration: The pre-project background sound and vibration levels. Used interchangeably with background or baseline sound and vibration levels.

dBA: Noise level adjusted to how humans experience different frequencies.

Air-borne noise: Noise transmitted by air.

Ground-borne noise: Noise generated by building/ structure components in response to ground vibration.

Ground-borne vibration: Vibration of building/ structure components in response to ground vibration.

Lpassby: Represents allowable noise level associated with a train passing by.

Vibration Velocity RMS, or Root Mean Square: Measure of vibration amplitude and an indication of vibration energy, also expressed as VdB.

Traction Power Substation: A facility that transforms the utility supply voltage for distribution to the trains.

Potential effects

Construction noise and vibration

• Without mitigation, there is potential for noise criteria and vibration criteria exceedances at some receptors near the surface construction sites along the alignment.

Operational noise and vibration

• Without mitigation, there is potential for stationary facilities noise criteria exceedances as well as exceedances of the ground-borne noise and vibration criteria at many receptors along the alignment.
• There are no predicted exceedances of the air-borne noise criteria from train operations at receptors along the alignment.

Mitigation measures

Construction noise

• Use equipment that meets the Provincial criteria in NPC-115.
• Ensure equipment is kept in good working order and operate with effective muffling devices where required.
• Provide smooth surfaces for vehicles to travel throughout the construction zones to help reduce impulsive noises such as tailgate banging of dump trucks.
• Develop construction staging plans that reduce noise at nearby sensitive receptors.
• This can include: Maximizing the separating distance from stationary equipment (such as generators and compressors) to the extent feasible, Selecting truck staging areas that are as far away from sensitive receptors as feasible, Designing optimal truck routes that minimize on-site movement (especially reversing) and avoiding travel along the quieter residential streets
• Schedule noisy activities during the daytime periods, where possible.
• Consider and erect temporary noise barriers or acoustic enclosures around noisy equipment such as concrete pumps, compressors, or generators and around long-term construction zones (such as the launch shaft), as required.
• Conduct real-time noise monitoring to identify sources of potential criteria exceedances and to implement additional mitigation measures to minimize the noise and vibration impacts, if required.
• Develop a communications protocol to provide notifications to the community on upcoming noisy activities, nighttime construction and their duration, and address complaints in a timely manner.

Construction vibration

• Implement vibration isolation solutions such as resilient fasteners for the temporary tracks used by the temporary service locomotives during tunneling or use of rubber-tired service vehicles, as required.
• Minimize the gaps between adjoining rail segments in the temporary tracks.
• Conduct regular inspection and maintenance of the temporary tracks, service trains and railway cars to minimize noise and vibration during tunneling operations.
• Schedule vibration intensive activities such as vibratory compaction during the daytime periods where possible.
• Complete pre-construction condition surveys and conduct monitoring in accordance with City of Toronto Bylaw 514-2008 as required.
• Maximize distance between equipment and sensitive receptors, where possible.
• Select construction/maintenance methods and equipment with the least vibration impacts, where possible.
• Operate construction equipment on lower vibration settings where available.
• Heavy equipment traveling over bumps or inconsistencies in the surface can generate higher vibration levels.
• Maintain smooth surfaces throughout construction zones to reduce vibration levels from such activities.

Operational noise

• Deploy vehicle and track technology and related maintenance measures.
• These include regular wheel maintenance (to ensure smooth and round wheels) and rail grinding (which ensures smooth rails).
• For the stations, traction power supply substations and portal structure, implement the following mitigation:
• All tunnel ventilation fan systems are to be provided with silencers, as required, to minimize noise and comply with the criteria outlined in MECP’s noise guideline for stationary and transportation sources (NPC-300).
• A 5.5m tall noise barrier at the Clark Station bus terminal, subject to further detailed design of the terminal.
• For the train storage facility, implement the following mitigation: A 5.5m tall noise barrier along the western extent of the train storage facility, subject to further detailed design of the TSF.
• Implement quiet special trackwork such as moveable point frogs.
• Select facility (stations, TPSS, and TSF) mechanical and electrical equipment to minimize sound levels and meet NPC-300 criteria.

Operational vibration

• Implement mitigation measures such as floating slab track, ballast mats, resilient fasteners and moveable point frogs, subject to further detailed design and studies, such as in-field measurements of the soils ability to transmit vibration.
• Implement regular vehicle and infrastructure maintenance such as rail grinding and wheel maintenance.

Read Appendix G - Noise and Vibration Existing Conditions and Impact Assessment Report

Key findings

• The Study Area includes a substantial road network and is served by both local and regional transit networks through a range of train, subway (currently limited to southernmost portion), and bus options, including the TTC, GO Transit and VIVA commuter lines.
• Freight trains operated by Canadian National Railway and Canadian Pacific Railway are also present. Existing means of transportation/transportation networks (including personal vehicles, transit, walking, cycling and rail) have the potential to be temporarily impacted during construction activities.
• Appropriate mitigation measures (see Potential Effects & Mitigation Measures on next slides) to be implemented during construction are anticipated to reduce or eliminate the potential impacts to the transportation network users.
• During project operations, minimal short-term impacts associated with maintenance activities (e.g., temporary lane/sidewalk closures) may occur.
• Consultation with local transportation agencies will occur should any potential modifications to the local transportation network, such as adjustments to transit service schedules, be required.

Potential effects

Construction phase

• Potential for temporary road lane, sidewalk, or bike lane closures.
• Potential re-alignment of road, sidewalk, or bike lanes in the area.
• Potential for access restrictions to local bus routes.
• Potential disruptions to rail services (e.g., CN Freight services) in the impacted area.
• Potential changes to special traffic lanes (e.g., removal of HOV lanes).
• Potential implementation of turn prohibitions at intersections.
• Potential changes to on-street parking regulations in the area. Potential changes to transit services schedules and routes.

Operational phase

• Minimal short-term impacts associated with maintenance activities (e.g., temporary lane/sidewalk closures) may occur.
• Potential for modifications to the local transportation network, such as adjustments to transit service schedules.

Mitigation measures

Construction phase

• Traffic Control and Management Plan(s) will be developed prior to construction.
• Access to nearby land uses will be maintained to the extent possible.
• Potentially affected residents, tenants and business owners will be notified of upcoming construction work and potential traffic impacts.
• In the event closures of sidewalks or bike lanes are necessary, safe alternative paths will be provided.
• Consult with rail operators with current service along the rail corridor (i.e., Canadian National Railway) to assess how track closures, if necessary, would impact their service and co-ordinate temporary schedules to accommodate all rail services on the open tracks.
• Ensure public is notified of the changes to turn prohibitions at intersections via additional signage.
• Ensure public is notified of changes to curbside lane regulations (e.g., parking, HOV lanes) via additional signage.
• Ensure that the public is notified in advance of any potential public transit service disruptions.

Operational phase

• Provide signage and detours in advance of temporary lane/sidewalk closures during maintenance activities, as required.
• Consult with local transit agencies regarding the potential changes to the local transportation network.

Read Appendix H - Transportation Existing Conditions and Impact Assessment Report

Key findings

• Construction activities, including tunnel construction and excavations at the launch, extraction shafts, below grade stations and emergency exit buildings will extend below the groundwater table but construction methods will be selected to minimize construction dewatering.
• Where groundwater is extracted, the groundwater will be treated, as required, to meet the relevant municipal sewer discharge by-laws.
• The potential for groundwater impacts will be further reviewed and documented in the Soil and Groundwater Management Strategy to be developed prior to construction, and appropriate mitigation measures implemented during construction (see Potential Effects & Mitigation Measures).
• As the tunnels, stations, and emergency exit buildings will be designed and constructed to resist pressures exerted by groundwater, permanent groundwater dewatering systems are not anticipated to be required for these structures.
• Accordingly, the structures are not anticipated to interrupt long-term existing groundwater migration pathways.
• Without mitigation, there is potential for impacts to soil (e.g., ground movement and settlement as a result of excavation).
• The completion of geotechnical investigations during detailed design, completion of soil management plans as planning progresses, and implementation of appropriate mitigation measures during construction are anticipated to minimize potential impacts (see Potential Effects & Mitigation Measures).

Potential effects

Construction phase

• Dewatering, if required, may cause local and temporary drawdown of the water table.
• If extensive dewatering is required, for example at underground stations and some emergency exit buildings, drawdown of the water table has the potential to impact the recharge of local natural surface water features, if within the dewatering Zone of Influence (ZOI; the area where the groundwater level is lowered by the dewatering activity).
• The potential for foundation settlement as a result of dewatering at the existing structures adjacent to the new alignment that have foundations built below the local water table.
• Displacement of soils as a result of construction activities may result in ground movement and settlement.
• Construction activities (e.g., excavation) could expose and/or result in the spreading of contaminated materials.

Operational phase

• On-going dewatering is not currently anticipated during operations.
• No impacts to soil are anticipated during operations.

Mitigation measures

Construction phase

• Prior to construction, conduct hydrogeologic assessments at dewatering locations to estimate/confirm groundwater flow rates, predict impacts (e.g., lowering groundwater table and features potentially impacted) within the dewatering ZOI, and evaluate treatment/discharge options.
• A Groundwater Management and Dewatering Plan will be developed to guide the handling, management, and disposal of groundwater encountered during construction and in accordance with applicable regulatory requirements.
• Best Management Practices (BMPs) will be implemented for managing groundwater, and contaminated groundwater will be managed in accordance with applicable legislation and regulations, such as O. Reg. 347 (as amended), O. Reg. 387/04, O. Reg. 63/16 and municipal discharge bylaws, in addition to the Project Groundwater Management and Dewatering Plan.
• 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 construction.
• 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.

Operational phase

• As on-going dewatering or impacts to soil are not currently anticipated during operations, no mitigation measures are required.