5. effects assessment and proposed mitigation during...

Horizon Hydro Operations Ltd. - Trout Lake River Hydro Project Environmental Report

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5. Effects Assessment and Proposed Mitigation During Project Construction This section documents the sources of effect, the potential environmental effects, and the mitigation measures that can be used to minimize/eliminate adverse effects during project construction on valued ecosystem and valued socioeconomic components (VECs and VSCs). Any net effects (i.e., residual effects remaining after implementation of mitigation) were then identified. Those net effects are then carried forward into Section 7 for further assessment for their significance.

Accidents and spills during construction can also potentially have negative effects on a number of VECs and VSCs. The potential sources of effect during construction, the potential negative effects and mitigation measures to minimize the potential effect of accidental spills are also assessed under each environmental component in this section.

5.1 Assessment Methodologies The assessment methodology utilized the steps outlined below:

1. Identifying the sources of effects associated with the Project (e.g., the Project construction methodology or Project components).

2. Identifying the potential effects on the VECs and VSCs that could potentially occur as a result of the sources of effects.

3. Identifying the mitigation measures that are proposed to prevent or minimize the potential adverse effects.

4. Identifying the net effects that would remain after the implementation of the specified mitigation measures.

The OWA Class EA Potential Effects Identification Matrix (Table 5.1) was used as guidance concerning the potential effects of the Project on the environment and the potential for mitigation. Accidental spills were also identified as a potential effect and included in these tables. These tables do not provide a detailed account of all potential effects and required mitigation measures but were included since they were considered the starting point for the assessment in order to identify potential areas where more information was required and mitigation may be necessary to address potential effects, with additional information derived from specific investigations taken into consideration in the subsequent sections, and then condensed in the summary table at the end of the section (Table 5.3), which summarizes all potential effects, mitigation measures and net effects following the implementation of mitigation.

The potential level of effect (positive or negative) in Table 5.1 is based on the guidance in the OWA Class EA (OWA, 2011) and the MNR Class EA (MNR, 2003). Accordingly, the following definitions of effect (OWA, 2011) were utilized:


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• a ‘nil’ effect would be assigned where there is no effect on that criterion,

• a ‘low’ potential effect would be assigned where the potential impact and/or benefit is considered low or minimal,

• a ‘high’ potential effect would be assigned where the potential impact and/or benefit is believed to be considerable,

• a ‘unk’ would be assigned where the potential effects are unknown or there is insufficient information to assign a potential level of effect with reasonable certainty,

• a ‘-‘ means a potential negative effect, and

• a ‘+’ means a potential positive effect.

The potential effects are identified as occurring before the implementation of mitigation measures, which would be enacted to prevent or minimize the adverse effects identified in the tables. The ‘Comments, Rationale’ column in the table identifies the potential effects that could occur, and the ‘Mitigation Measures’ column identifies the measures proposed to prevent or minimize adverse effects.

5.1.1 Potential Effects Potential effects due to the Project were determined via a variety of means including:

• review of published data from peer-reviewed studies of effects in scientific journals,

• review of published data from monitoring results of hydroelectric facilities in Canada,

• review of guidance documents from regulatory authorities, including Pathways of Effects diagrams,

• through consultation with stakeholders including Aboriginal communities, government agency personnel and members of the public regarding their understanding of potential effects,

• through the knowledge and past experience of the environmental assessment (EA) authors on similar types of projects in Ontario and throughout Canada, and

• through information collected during the various studies within the project area.

For every VEC and VSC, each activity of the Project is reviewed to determine if that activity has the potential to have a positive or negative effect on the VEC or VSC. This activity was completed using the Potential Effects Identification Matrix from the OWA Class EA document.

5.1.2 Mitigation Measures Mitigation measures are actions that are taken to prevent negative effects from occurring, or to minimize the impact of negative effects by decreasing the magnitude, geographic extent, timing, duration or frequency of the net effect.


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Table 5.1 Potential Construction Effects Identification Matrix

Criteria Potential Level of Effect Comments, Rationale Mitigation Measures -H -L Nil Unk +L +H

General Natural Environment Considerations Air quality, including noise and green house gas (GHG) offsets

X

• Potential adverse effects during construction due to noise from heavy equipment and blasting operations. Air quality effects will include equipment exhaust, smoke from burning waste materials, and dust emissions including those from the rock crusher machine.

• Standard construction site best management practices to minimize noise and air emissions due to exhaust and dust. Waste burning would apply to clean wood waste materials only.

Water quality or quantity (surface water)

X • Potential adverse effects on water quality during construction due to erosion and sedimentation and accidental spills.

• Standard construction site best management practices to control erosion and sedimentation and prevent accidental spills from occurring.

• Short transmission line and access road will minimize potential effects. Winter construction would be preferred to minimize impacts.

Water quality or quantity (groundwater)

X • Potential adverse effects on groundwater quality during construction due to accidental spills.

• Potential decreases in local groundwater quantity during construction due to groundwater leakage into project excavations.

• Standard construction site best management practices to prevent accidental spills and manage groundwater.

Species at risk or their habitats X • A number of bird species (bald eagle, common nighthawk, olive sided flycatcher, Canada warbler and rusty blackbird) are present or have suitable habitat conditions within the general project area.

• Short term disturbance is possible due to noise and construction activities, but no long term adverse effects are anticipated.

• Timing of forest clearing undertaken in accordance with Environment Canada guidelines to avoid effects to breeding birds

X • Woodland Caribou and Wolverine are present within the regional area, but not likely present within the zone of influence of the Project. Studies on the island at Big Falls have found no evidence of use by Caribou. No adverse effects are anticipated on Woodland Caribou or Wolverine since the site is in close proximity to an existing forest access road and use of the Project area is likely minimal due to fragmented/disturbed habitat in general area.

• No specific mitigation is required.

X • Snapping Turtle may be present in project area, particularly in the wetland within the proposed head pond. Snapping turtle are not anticipated to use the portions of the project area that will be affected during construction. Turtle nesting areas are not known to be present within the inundation zone for the proposed head pond, but head pond inundation will occur outside the Snapping Turtle nesting, incubation and hatching period, so no effects on reproduction are anticipated. Flow will not be disrupted in the river upstream from Big Falls during construction, so no negative effects on areas that could potentially be used as over-wintering habitat are anticipated to occur. However, some disruption could occur to any turtles that do utilize areas within the project footprint, or do cross project access roads or South Bay Road during construction.

• Head-pond inundation will not occur during the turtle nesting, incubation and hatching period.

• Construction staff will be made aware of the potential for turtles, as well as other wildlife, crossing project access roads and will be instructed to drive carefully and avoid turtles that are observed.

Significant earth or life science features

X • No significant earth or life science features designated by MNR are known to exist in the Study Area.

• N/A

Land subject to natural or human-made hazards

X • No significant natural hazards are known to have been identified within the Study Area.

• N/A

Terrestrial wildlife (including numbers, diversity and movement of resident or migratory species)

X • Terrestrial wildlife could be affected by loss/fragmentation of habitat (associated with construction of site facilities and associated infrastructure including transmission line and access roads, as well as head pond creation, etc), and disturbance associated with construction of the proposed facilities.

• Habitat loss associated with the Project will be minimized to the greatest extent possible.

• Short transmission line and access road minimizes potential for interference with wildlife habitat features.

• Vegetation removal and head-pond filling will occur outside of the nesting seasons. Natural vegetation and terrestrial habitat linkages

X • Natural vegetation and terrestrial habitat linkages will be affected by clearing associated with construction of site facilities and associated infrastructure, including transmission line, head pond creation, etc), accidental spills/malfunctions.

• Extent of clearing associated with the Project is minimal. • Short transmission line avoids significant wildlife habitat features. • Other best management practices will be employed to minimize potential impacts.


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Soils and sediment quality X • Soil and sediment quality could be adversely affected by excavation and removal, compaction, loss due to fugitive dust or erosion or accidental spills during construction.

• Construction site best management practices will be implemented for erosion and sedimentation control, dust management and prevention/containment of accidental spills to limit the potential for adverse effects on soil and sediment quality.

Significant natural heritage features and areas

X • No significant natural heritage features are known to be present within the study area.

• N/A

Other (specify) X • No other components identified. • N/A Aquatic and Riparian Ecosystem Considerations Shoreline dependant species X • Shoreline dependant species may be impacted by the creation of the project head

pond, which will inundate existing shorelines.. • Head pond inundation timed to minimize potential impacts on shoreline dependant

species (e.g., furbearers), if possible. Guidance will be sought from local First Nations and/or local trapper on preferred method of movement/relocation.

• Natural regeneration of shoreline habitat will eventually restore these areas for use by shoreline dependant species. The amount of shoreline length is anticipated to increase as a result of head pond creation.

Wetland dependant species X • A small wetland in the embayment immediately upstream from the proposed dam location is classified as W5 (Marsh: mixed: mineral substrate, while the deeper open water area adjacent to this is classified as W1 (Open Water Marsh: mixed: mineral substrate. However, extensive wetland habitat is present upstream from the zone of influence of the Project and will not be affected by construction, thereby providing extensive similar habitat types as the small wetland that will be inundated during head-pond filling.

• No mitigation possible to prevent inundation of wetland upon filling of the head pond, but over time it is anticipated that open water/shoreline wetland conditions will develop along the shorelines in the area.

Fish habitat X • Fish habitat will be temporarily affected by in-stream construction for the overflow weir and tailrace, including cofferdam installation and associated dewatering, head pond inundation, and adverse effects due to sedimentation and potential spills (the permanent effects of the facility are assessed in the operations section (Section 6) and are not considered further in this section.

• Construction and in-water work best management practices to minimize potential for erosion and sedimentation and accidental spills.

• In-water work timing windows will be followed to prevent impacts during reproductive periods.

Fish migration X • The base of the South and North Channels of Big Falls is considered to be a barrier to upstream fish movement, so there is no migration upstream through Big Falls. MNR and DFO agree that Big Falls is a barrier (see agency correspondence in Appendixes C8 and C9). Fish are anticipated to migrate downstream through Big Falls to any significant degree, given that downstream movement represents a permanent loss to the upstream population, although some downstream movement could occur periodically. Although structures will be in place across the river during construction, downstream from will be maintained at all times through various passage means, therefore fish would always be able to move downstream through Big Falls. Upstream migration from Bruce Lake to Whitefish Falls (a known migratory pathway) and to the base of Big Falls will not be negatively affected during construction, since there will not be any significant changes in flow in the Trout Lake River due to construction.

• Head-pond filling will be restricted to 10% of the instantaneous river flow to limit short term changes during the short head pond filling period (2 to 3 days), which will prevent changes in river flows in the Trout Lake River downstream from Big Falls, which includes a known migratory pathway from Bruce Lake to Whitefish Falls. Given the low gradient of the Trout Lake River, minor changes in flow are not anticipated to cause any change in water level that would affect the ability of fish to migrate upstream in this area.

Fisheries X

• Fisheries could be affected during construction by minor disturbance due to in-water work, flow diversion, temporary loss of habitat associated with Project footprints (e.g., cofferdams and working areas) and minor alterations in water quality due to erosion and sedimentation.

• Construction and in-water work best management practices to minimize potential for erosion and sedimentation and accidental spills.

• In-water work timing windows will be followed to prevent impacts during reproductive periods.

Erosion and sedimentation X • Potential for erosion and sedimentation due to construction activities (e.g., ground disturbance, stormwater management, flow diversion, head pond filling).

• Standard construction site best management practices to minimize erosion and sedimentation potential during construction.

Fish injury or mortality X • Potential for fish injury due to blasting in or near water. • Blasting will follow DFO requirements for protection of fish and fish habitat to minimize potential risk of fish injury or mortality.

• In-water blasting, if necessary, will not be conducted during reproductive periods. • Non-ANFO blasting products will be utilized.


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Drainage, flooding and drought patterns

X • Minor changes in local drainage could potentially occur due to presence of facilities, laydown and work areas, access road and transmission line.

• Drainage measures will be installed around Project components that have the potential to significantly alter local drainage including ditches along access roads.

Water temperature X • No changes in water temperature anticipated to occur during construction. • N/A Other (specify) X • No other components identified. • N/A

Aboriginal Community Considerations Spiritual, ceremonial, cultural, archaeological, or burial sites

X • Disturbance to spiritual, ceremonial, cultural, archaeological or burial sites could occur during construction activities.

• Stage 1 and 2 Archaeological Assessments found no features that would be affected by construction of the project. MTCS has issued letters confirming these findings. Response protocols will be in place should previously undiscovered sites or artifacts be unearthed during construction.

Traditional land or resources used for harvesting activities

X • Effects to the aquatic and terrestrial environment (discussed above) may result in negative effects to traditional lands and resources used for harvesting activities.

• Inundation of small wild rice bed along east shore of head-pond area immediately above dam. Bed is not part of a licensed wild rice harvesting area and there is no known harvester of the rice.

• Potential loss of traditional medicinal plant species due to Project development.

• Mitigation measures to minimize effects to terrestrial and aquatic environments to minimize potential effects on traditional land or resources used for harvesting activities.

• Identify appropriate area within proposed head pond and develop plans for replacement habitat during final design.

• The Project area will be walked with an expert Aboriginal community member to identify traditional medicinal plants. If necessary, a mitigation plan will be developed jointly with Aboriginal communities for implementation prior to construction.

Employment X • Construction of the project will potentially result in opportunities for employment of Wabauskang, Lac Seul and Grassy Narrows First Nation community members.

• N/A

Lands subject to land claims X • The Project area lies within an area that has been used for traditional purposes by the Aboriginal communities of the area. These include the Lac Seul First Nation, Grassy Narrows First Nation, Wabauskang First Nation and the MNO. Trout Lake River is part of a traditional travel route to Trout Lake. The Project area also lies within the boundaries of Treaty 3 (1873).No land claims are known to exist in the area.

• N/A

Economic Development X • The Project will provide income to First Nations communities should they decide to enter into partnership agreements with Horizon and potential employment opportunities to the local communities as well.

• N/A

Other (specify) X • No other components identified • N/A Land and Resource Use Considerations Access to inaccessible areas (land or water)

X • The site is close to (within 200 m) and readily accessible from South Bay Road via the trail used to access the Water Survey of Canada gauge located above Big Falls. Access to the area by water will remain via portage routes.

• Public access to the construction area will be prohibited to ensure public safety. Portage routes around the sites will be constructed/restored to ensure safe passage during construction.

Navigation X • East shore portage route at Big Falls will be affected by the proposed development. • Existing portage route on the west bank will be unaffected. Signage will be posted to advise that the east side route is not available during the construction process.

Riparian rights or privileges X • The Project Area, including the head-pond shoreline is on provincial Crown land. No riparian rights or privileges are known to exist.

• N/A

Recreational use (land or water) X • Some limited recreational use of the area (angling) is known to occur and there is an interpretive trail created by MNR is present adjacent to the north channel of Big Falls.

• Access to downstream area unaffected. West side Portage will be maintained to ensure safe passage around the work area during construction.

Angling and hunting opportunities X • Angling and hunting opportunities within the local area during construction will be restricted due to worker and public safety concerns.

• Appropriate mitigation measures are being currently discussed with the BMA holder.

Trapping activities X • The Project is located within a licensed trapping area. Trapping activities may be affected during construction.

• Appropriate mitigation measures (if needed) will be determined through consultation with licensed trapper.


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Baitfish harvesting activities X The Project is located within one licensed baitfish harvesting area (BHA), although current harvesting sites are unknown. If the Project area is a harvesting site, some effects could occur during construction.

Appropriate mitigation measures (if needed) will be determined through consultation with licensed harvester.

Views or aesthetics X Construction of the Project will result in a change to aesthetics of the area due to vegetation removal, presence of construction workforce and machinery and work in water (e.g., cofferdams). No concerns from the stakeholders have been raised regarding effect during construction.

No mitigation possible to prevent short term changes in aesthetics during construction.

An existing land or resource management plan

X The Project area is located within Land Use Policy Atlas Report G2514: Red Lake, which is a general use area. The identified management directions for this area indicate that commercial hydro development will be permitted. In particular reference to renewable energy generation. Therefore, the Project is consistent with the land and resource use intent of the area.

N/A

An existing water management plan X There is no existing water management plan for Trout Lake River. Simple water management plans will be prepared for the facility. Protected areas X Provincial Parks and Nature Reserves in the vicinity of the Project include Bruce

Lake Conservation Reserve, Bruce Lake Forest Reserve, Pakwash Provincial Park, Trout Lake Conservation Reserve, and Trout Lake Provincial Nature Reserve. None of these Provincial Parks and Reserves is within the zone of influence of the project.

N/A

Other (specify) X No other components identified. N/A Cultural Heritage Resources Considerations Archaeological sites X The Stage 1 and 2 Archaeological Assessments did not identify any archaeological

sites. N/A

Buildings or structures X No buildings or structures are present within the zone of influence of the Project. N/A Cultural heritage landscapes X There are no built heritage features in the zone of influence. N/A Other (specify) X WSC gauge station within area that will become the project head pond. Horizon has been in contact with Water Survey of Canada and arranged and paid

for the relocation of the station to an alternate location further upstream.

Social and Economic Considerations The location of people, businesses, institutions, or public facilities

X Construction of the Project will have no effect on the location of people, businesses, institutions, or public facilities.

N/A

Community character, enjoyment of property, or local amenities

X Construction of the Project will have no effect to community character, enjoyment of property and local amenities.

N/A

Employment X The construction of the Project will require local and non-local employment based on qualification.

N/A

Public health and/or safety X Public safety risks/concerns normally associated with run-of-river hydroelectric stations will be present during construction.

Prevention of public access to the construction site through use of signage, gates and fencing among other security procedures as required.

Local, regional, or provincial economies

X Economic benefits will include employment, expenditures on materials, equipment and services, contribution of renewable energy to the Provincial supply mix.

N/A

Tourism values X Big Falls provides a scenic view, and the Project Area is known to provide tourism use.

N/A

Water supply X The Trout Lake River within the Study Area does not provide a water supply for local communities.

N/A

Other (specify) X No other components identified. N/A Energy/Electricity Considerations Reliability (e.g., voltage support) X No effect during construction. N/A Security (e.g., black start) X No effect during construction. N/A Electricity flow patterns X No effect during construction. N/A


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Mitigation can take several forms ranging from mitigation implemented during planning stages of the Project to mitigation measures that are implemented and are physically “in-place” (i.e., such as silt fencing) during the Project. The general types of mitigation considered for this Project include:

• modifying the types of construction activities,

• modifying the Project components or the way in which those components operate,

• modifying the schedule of Project activities so they occur outside of sensitive time periods,

• installing treatment technologies (e.g., erosion and sediment control measures), and

• compensating for the effect by enhancing or creating a positive benefit elsewhere (e.g., creating new fish spawning beds to compensate for loss of an existing spawning bed).

The hierarchy of the preferences for mitigation are to (i) attempt to prevent the effect from occurring, (ii) minimize the impact of the effect to acceptable levels, and finally, least preferred, (iii) compensate for the effect elsewhere. Mitigation strategies for each identified net effect were reviewed with this hierarchy in mind, although technical or economic constraints may also influence this process.

Mitigation measures have been identified using existing documentation (e.g., Mitigation of Aquatic Ecosystem Impacts for New Dams and Waterpower Facilities in Ontario: A Summary of Existing Knowledge (Marshall Macklin Monaghan, 2007), standard industry best management practices (BMPs), based on similar past experience on other Projects by Hatch, and through discussions with stakeholders including Aboriginal communities, regulatory agencies and members of the public. In addition, the OWA has recently published a manual of ‘Best Management Practices for the Management of Impact of Waterpower Facility Construction’ (OWA/Genivar/NRSI, 2012), which will be referenced in contract documents for this project.

5.1.3 Net Effects Net effects are the positive or negative effects that are anticipated to occur following the implementation of the identified mitigation measures. The determination of net effects takes into consideration the ability of the specified mitigation measures to prevent a potential effect from occurring or to minimize the characteristics of the effect. Net effects are determined based on the known or predicted effectiveness of mitigation.

Where possible, the net effect has been quantitatively evaluated (e.g., areas of habitat impacted), although in some cases, it is not possible to quantify the effect, and a qualitative assessment has been made.

Net effects include effects that are anticipated to occur, as well as effects that have a risk of occurrence (i.e., they may or may not occur).


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5.2 Sources of Effect Construction of the facility is anticipated to occur over approximately a 12 to 18 month period. The following are the major construction to be undertaken in the implementation of the project:

• access roads,

• site preparation, including clearing/grading of lay down and works yard,

• overflow weir (including temporary diversion sluices and permanent compensation flow valve),

• water conveyance features (intake channel, intake structure and steel penstock),

• powerhouse and tailrace,

• switchyard and transmission line,

• head-pond clearing and filling,

• waste management, and

• site rehabilitation and cleanup.

These activities that are anticipated to be source of effects are described below.

Access Roads Access to the site will be via the existing South Bay Road, which runs northward from Highway 657 in the Town of Ear Falls (approximately 30 km away), passing immediately to the east of the project area (Figure 1.1). South Bay Road is a multi-use public access road located on Crown land. It is currently in good condition. No upgrading will be required for this project.

New access roads will be required to the intake and powerhouse areas to facilitate construction and permanent access to those facilities (Drawing 327203-SK-001 in Appendix A). The section of new road from South Bay Road to the intake structure will be approximately 200 m long and the road to the powerhouse (which branches off from the intake access road) will be 80 m long. The road to the powerhouse will utilize the transmission line ROW. A parking area sized to accommodate a mobile crane will be constructed at both the intake and powerhouse.

Temporary access will be required to overflow weir and intake channel working areas. Temporary roads will be constructed to a standard capable of handling the proposed construction equipment (i.e., hard pack dirt with granular topping, if required), and will be decommissioned following the completion of construction in these areas.

Steps in the construction of the new access roads include: clearing a 14-m wide corridor, grubbing, grading/rock removal (blasting if required), placement of granular and grading. The final road will have a surface width of 6 m. No water crossings will be required along any of the access road sections. Ditches will likely be constructed along each side of the access road to provide surface drainage.


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Construction mobilization and site preparation will be the first activity followed by construction of the new access roads to the intake and powerhouse sites. A crusher will be set up on site to turn excavated rock into aggregate suitable for road construction.

Site Preparation Including Laydown Area and Works Yard Site preparation will occur following installation of access roads to the intake, overflow weir and powerhouse areas. These will include clearing of trees, grubbing (e.g., removal of stumps) topsoil stripping, grading and potentially blasting in the working areas.

It is estimated that approximately 5000 m2 of land will be cleared for temporary facilities such as works and laydown areas (features will be subject to the final design of the contractor). A primary laydown area will be established to the east of the worksite to provide an area for storage of equipment, supplies, materials, rock crusher, and construction facilities such as temporary trailers and washrooms. Several smaller areas may be provided near each structure. It is estimated that approximately 25,600 m2 of land will be cleared for permanent works. Of this amount, approximately 10,500 m2 of land will be cleared for the main work area and access roads. Working areas will also be cleared at the overflow weir (350 m2), intake (450 m2), intake channel (6500 m2), penstock (2000 m2), powerhouse (1000 m2), and transmission lines (4800 m2) to facilitate construction of these components.

Overflow Weir The general layout, longitudinal profile and cross section for the proposed weir are shown on Drawings 327203-SK-002 and -003 (Appendix A). The construction methodology for the overflow weir will be a two-step process in which flow is diverted to one side of the river while one section is constructed, and then switched to the other side to complete the remaining portion. A rock-fill cofferdam with an impervious barrier will be installed along the left bank (looking downstream) to construct the left side of the spillway, including diversion bays, in the dry. Flow in the river will be directed toward the right side of the channel (see Figure 5.1). Once the left hand side of the structure is complete, the cofferdam will be removed and a similar cofferdam will be installed on the right-hand side of the river channel. At that point, construction access to the west side of the river will be gained over the diversion structure, and all flow in the river will be diverted through the diversion bays in the east section of the weir. Once the overflow weir is complete, the west side cofferdam will be removed.

Water Conveyance Features and Associated Components The intake channel will be constructed in the dry behind an earth/rock plug at the entrance to the intake on the east shoreline. A small sand bag cofferdam may be required at the upstream end of the channel to prevent submergence during an extreme high water event in the Trout Lake River during the construction period. Installation of any required erosion protection will be done prior to the removal of the plug. Removal of the plug will be undertaken at low river flow before raising of the head pond. Excavation of the intake channel will generate a total of approximately 2100 m3 of waste rock, which will be crushed and reused for local road construction/erosion protection materials.


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The intake structure (located at the east end of the intake channel) and the penstock will be constructed completely in the dry without any requirement for cofferdam construction.

Powerhouse and Tailrace Powerhouse construction will occur behind a rock plug at the shore of the Trout Lake River. Some topping of the rock plug with rock fill or sand bags will be required to ensure adequate freeboard during flood events. No in-water cofferdam will be required to construct the powerhouse. Excavation of the powerhouse will generate approximately 2600 m3 of waste rock and 800 m3 of earth.

The tailrace will be constructed downstream from the powerhouse draft tube to convey flow back to Trout Lake River. The first 3-m long section of tailrace will be constructed behind a rock plug (i.e., the existing bedrock along the shoreline). Excavation and grading of the remaining portion of the tailrace will be done in the wet behind turbidity curtains.

Switchyard and Transmission Line The station switchyard and main transformer will be installed to the southeast of the powerhouse within an approximately 20-m by 10-m (200-m2) enclosure, with a crushed stone filled basin to contain spills and provide fire protection. The area will initially be cleared/ graded during site preparation, and finish graded/fenced once powerhouse construction is completed.

The transmission line corridor (up to 38-m wide ROW) will be cleared during site preparation. No stream crossings are present along the proposed route and no grubbing (i.e., removal of stumps) is required, other than within the access road corridor.

Other Components A sediment settling pond will be required on site to treat water collected from construction activities and excavations, as well as any stormwater runoff that requires treatment. The settlement pond will be used for dewatering excavation sites behind rock plugs and/or cofferdams. Any treatment of wastewater being discharged to a watercourse will require approval through an ECA. Further details will be provided during the permitting stage.

It is anticipated that all concrete for the overflow weir, intake channel, intake structure, penstock anchor blocks and powerhouse will be sourced from a local, off-site ready-mix batch plant and delivered to the site by truck. Concrete trucks will be rinsed at a designated rinsing location in the work yard. Rinse water will be contained and treated (as required) prior to release to the watercourse. Some dry cement storage (i.e., in bags) may occur on site.

A washroom facility may be installed in the proposed powerhouse and a small wash sink will be present. Non-potable water will be drawn from the river for use at the facility if required.

Trout Lake River Hydro ProjectHorizon Hydro Inc.

River Diversion Stages

Stage 1 Diversion

Stage 2 DiversionScale 1:750

30150 Metres

Figure 5.1


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Back of figure


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Head Pond Clearing and Filling Clearing of vegetation within the proposed head-pond area (6.3 ha) and removal of downed woody debris will be undertaken prior to filling. All trees and shrubs greater than 0.05 m diameter located within the proposed full supply level (to elevation 368.8 m) will be cleared and removed from the area. No grubbing will take place. Stumps will be left at a maximum of 0.30 m above grade to provide erosion control and shoreline protection. Clearing will take place by chainsaw and/or feller-bunchers. Skidders may be used to haul the cleared timber from the inundation area. Merchantable timber will be provided to Domtar (SFL holder) and non-merchantable timber will be piled above the maximum inundation elevation of the head pond (to decompose or be burned at a later date).

After completion of the intake and overflow weir, filling of the head pond will raise the upstream water level to a normal elevation of 368.8 m. This will increase the wetted surface area of the 1.7 km long reach upstream of the overflow weir from approximately 9.5 ha (river surface area at average flow) to approximately 15.8 ha (6.3 ha additional area). Head-pond filling will be one of the final project implementation activities. During head-pond filling, the river flow will be restricted by no more than 10% of the instantaneous river flow.

Waste Management It is estimated that approximately 5500 m3 of waste rock and approximately 27,000 m3 of earth, including both topsoil and subsoil will be generated during construction of the facility. Much of the rock will be reused during access road construction, while the remainder will be used for erosion protection (i.e., riprap) along the dam embankments. A rock crusher will be located at the laydown area to turn excavated rock into aggregate suitable for road works. Soils will be reused to the extent possible, with the remainder transferred to a disposal area along the access road (if required). Topsoil and organic materials will be stockpiled for reuse in site restoration activities.

All by-products from the clearing will be reused. This includes any merchantable timber, non-merchantable timber and brush. All wood that cannot be sold will be chipped and used as mulch during project restoration activities or burned. Burning (if undertaken) will be completed in accordance with applicable regulatory requirements.

Industrial liquids to be used on site during the construction process include fuels, lubricants, hydraulic fluids, paints, sealants and others. All liquids will be properly stored in designated areas away from the watercourse. All waste industrial liquid will be transported off site, by a designated waste hauler registered to transport the appropriate class of hazardous waste to a designated waste disposal site approved to receive the appropriate class of hazardous waste.

Solid wastes generated during construction will include domestic waste such as food and sanitary waste, and construction waste such as material packaging and scrap material. Sanitary facilities on site will include several portable self-contained toilets and washroom facilities in a crew trailer. All solid and sewage wastes will be contained and hauled off site by a designated hauler throughout the construction period. Any waste that can feasibly be reused or recycled will be. All municipal waste will be transported to an MOE licensed landfill by an MOE licensed hauler.


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Site Cleanup and Rehabilitation Upon completion of the construction phase of the project, the contractor will be required to rehabilitate the site. The purpose of site rehabilitation is to minimize the potential for soil erosion, provide improved wildlife habitat and improve aesthetics of the area. Rehabilitation will include removal of all construction materials and wastes, and grading and revegetation of all exposed areas that may be prone to erosion. Where natural erosion protection measures may not be possible or practical, suitable physical erosion protection methods will be used.

5.3 Effects and Mitigation – Natural Environment

5.3.1 Terrain and Topography Terrain and topography refers to the elevation of the land surface and the type of surficial materials present on that surface. Terrain and topography are physical characteristics of the land that can affect a number of other environmental components including vegetation communities, surface water drainage, groundwater recharge, flow or discharge, and wildlife habitat.

Construction activities will result in the excavation of approximately 5500 m3 of bedrock from the various construction areas, and redistribution of those materials around the project site (primarily used for access roads, base materials for construction laydown, switchyard and parking areas, and some for erosion protection materials). Bedrock excavation will result in a decrease in the bedrock resource of the study area and will alter the bedrock topography in the vicinity of the excavations. However, the local bedrock features are not known to exhibit any significant geological or landform characteristics and the redistribution will not significantly affect local landforms. Blasting that will be undertaken in a controlled manner to prevent adverse effects on adjacent rock formations (e.g., stability, creation of faults, etc). A licensed blasting contractor will be retained to design and implement the blasting program.

An estimated 27,000 m3 of surficial soils are planned to be removed from the site and/or relocated during project construction. All subsoils that are not required on site will be moved off site to a suitable location. All stripped and excavated topsoil will be temporarily stockpiled on site until site restoration needs are established, and restoration activities completed. Any excess topsoil or organic materials will be transferred off site. Removal of this material will result in the need to re-establish local drainage patterns on site, and restoration activities will re-establish vegetation communities, and eventually wildlife habitat. While site excavation, construction and restoration activities will change the physical characteristics at the site, the site area is small compared to the surrounding area, and will mostly re-establish (with the exception of permanent structures) over time.

5.3.2 Soil Quantity and Quality As noted above, an estimated 27,000 m3 of surficial soils are expected to be removed and/or redistributed during project construction. Stripped and excavated topsoils will be stockpiled on site until ready for use during site restoration activities. In addition to excavation, surficial soils will be disturbed throughout the construction process due to vegetation clearing, topsoil and subsoil stripping, grading and use of heavy machinery.


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5.3.2.1 Erosion and Sediment Transport Soil disturbance, exposure and stockpiling have the potential to increase soil erosion and sediment transport due to the effects of water (rain, river flow) or wind. In order to mitigate this potential, a number of construction best management practices related to sediment and erosion control will minimize the amount of soil disturbance occurring on site. These measures will be included within a sediment and erosion control plan that will be prepared by the proponent’s contractor following completion of detailed design. Measures to reduce adverse effects related to erosion and sediment transport include:

• minimizing the size of the cleared and disturbed areas at the construction site, particularly those adjacent to the watercourse,

• phasing of construction to minimize the time that soils are exposed,

• restricting work areas to minimize the overall amount of soil disturbance during construction,

• providing an adequate supply of erosion control devices (e.g., geotextiles, revegetation materials) and sediment control devices (e.g., in-water silt barriers, silt fences, straw bales) on site to control erosion and sediment transport, and respond to unexpected events,

• inspecting erosion and sediment control devices on a daily basis and during high runoff events to ensure they are functioning as intended,

• providing adequate training in the deployment and maintenance of erosion and sediment control devices to ensure they are properly installed and maintained (i.e., excess materials removed from behind silt curtains and/or check dams),

• diverting work area runoff through vegetated areas or into properly designed and constructed sediment traps or a drainage collection system to ensure that exposed soils are not eroded. Runoff velocities in ditches or other drainage routes, or along slopes, to be kept low by the construction of flow check dams, offshoot drainage channels or other suitable mitigation measures, as described in the Environmental Guideline for Access Roads and Water Crossings (MNR, 1990). Runoff outfall locations to be protected with erosion resistant material, if required.

• use of a settling pond for treatment of effluent from dewatering operations within excavations or behind cofferdams. Dewatering activities will require a PTTW if the rate is in excess of 50,000 L/d. Dewatering effluent treatment operations will require an Environmental Compliance Approval (ECA) for Industrial Sewage Works under Section 53 of the Ontario Water Resources Act (OWRA).

• use of only clean materials (i.e., free of fine sediment) for in-water (e.g., cofferdam construction, fish habitat enhancements), or shoreline works (e.g., embankment riprapping),

• undertaking in-water work within a cofferdam (i.e., in the dry),


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• grading disturbed slopes or stockpiles to a stable angle as soon as possible after disturbance to eliminate potential slumping,

• revegetating or stabilizing exposed sites as soon as possible after they have been disturbed, using quick growing grasses or other vegetation. Where revegetation is not possible other erosion protection methods, such as riprap, bioengineering, or erosion matting to be used, and

• stockpiling of excavated materials in suitable designated areas away from the river (i.e., outside the floodplain, away from drainage channels). Install silt fences around the stockpiles to limit the transport of sediment.

Tree clearing within the proposed head pond, particularly on steep slopes, could potentially result in soil erosion, with adverse impacts on surface water quality. MNR (1991) indicated that slopes over 40% gradient are generally not able to be cleared with conventional forest harvesting equipment and that slopes between 10% and 40% have a high potential for erosion if the surface organic layers are removed. Therefore, in order to minimize the potential for slope erosion in areas to be cleared adjacent to watercourses and in the proposed head pond, the following mitigation measures will be applied:

• using extra long winch cables,

• careful selection of skid trail locations,

• skidding along the slope contours where safety allows,

• avoiding repeated use of the same skid trail,

• following slope contours when using heavy site preparation equipment, and

• time clearing of steepest and/or most erosion prone areas, such that it occurs shortly before head-pond filling so that these areas are not exposed to rainfall, runoff and wind for a long duration.

Implementation of these mitigation measures is anticipated to be effective in minimizing soil erosion as well as off-site transport from the construction area. Monitoring is to be conducted throughout the construction period to assess the effectiveness of mitigation measures and remedial requirements (see Section 9 – Environmental Monitoring Programs). However, mitigation is not likely to be 100% effective in preventing/controlling erosion and sediment transport throughout the duration of the construction period. Therefore, it is necessary to assume that some small amount of soil erosion and transport may occur periodically due to failure of erosion/sediment controls. It is anticipated that the monitoring program described in Section 9 will be effective in identifying such failure and ensuring that remedial actions are initiated as soon as possible to limit the magnitude and spatial scale of any erosion and associated sediment transport.

5.3.2.2 Stockpiling of Soils Stockpiling of soils has the potential to have an adverse effect on the health of the soil within the stockpile, which could affect its ability to support biological life, including vegetation and


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wildlife, once it is spread for reuse during the restoration period (Abdul-Kareem, A.W. and S.G. McRae. 1984). Effects on soil health could include compaction, creation of anoxic conditions and changes in soil texture or structure in the topsoil or subsoil, particularly if the different soil types are mixed in stockpiles. Stockpiling to depths >1 m may result in adverse effects on the health of the soils at the base of the stockpile (Harris and Birch, 1989; cited in Strohmayer, 1999).

It is recommended that the following mitigation measures be implemented by the contractor to minimize adverse effects on soil (e.g., mixing, compaction, etc) during the construction period:

• topsoil and subsoil is to be stockpiled separately to avoid mixing, which could adversely affect the quality of topsoil,

• the duration of stockpiling is to be minimized to the greatest extent possible through appropriate phasing of construction, and

• the height of topsoil stockpiles should be limited to the greatest extent possible, with heights of <1 m being preferred.

Mitigation is anticipated to be effective in minimizing the adverse impacts on soil, although some minor deterioration of the quality of stockpiled topsoil may occur. Monitoring will be conducted following site restoration to ensure that revegetation was successful, and will reduce any site erosion concerns (see Section 9.3). Remedial action will be undertaken as deemed necessary to ensure that revegetation is successful in preventing erosion within areas disturbed during construction.

5.3.2.3 Soil Compaction Soil compaction may result from the use of heavy equipment, loading with heavy materials (e.g., excavated rock) or additional of granular fill to temporary work areas. Soil compaction occurs when heavy equipment or material causes the soil particles to be pushed together, thereby increasing soil density and reducing the pore space within the soil structure (DeJong-Hughes et. al., 2001). Excessive soil compaction can result in inhibited vegetation growth by impeding root penetration within the soil, reducing aeration, and altering moisture intake (i.e., decreased infiltration and due to decreased pore space within the soil structure) (DeJong-Hughes et. al., 2001). Decreased water infiltration into the soil could also potentially result in an increase in surface runoff which could increase soil erosion along the runoff route and decreased groundwater recharge, which could potentially affect groundwater levels, vectors and discharge points.

In order to minimize the amount of compaction that occurs around the construction site, all equipment and stockpiles must remain within identified work areas. Monitoring will be undertaken prior to site restoration to identify areas of extensive compaction that could potentially inhibit revegetation. Monitoring would involve visually assessing the work area for the presence of rutting due to heavy equipment tracking or flat areas of topsoil that may have undergone compaction due to stockpiling or equipment storage (see Section 9.2 – Construction Phase). Remedial efforts (e.g., sub-soiling or other soil loosening methods) will


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be undertaken as required to prevent significant long-term impacts due to excessive amounts of compaction. No significant long-term change in soil structure is anticipated following implementation of site restoration and associated mitigation to remediate significantly compacted areas, although minor amounts of compaction may persist in localized areas.

No long-term change in native soil texture (i.e., the relative proportion of different grain sizes within the soil matrix) within the construction area is anticipated to occur.

5.3.2.4 Bank Stability Shorelines and riverbanks at the locations of the proposed overflow weir, intake and powerhouse/tailrace will be disturbed during construction. Riverbanks in the overflow weir area are a mixture of bedrock, rocky material and clay. Riverbanks in the vicinity of the intake channel entrance are predominantly clay. The riverbank at the powerhouse/tailrace location consists predominantly of exposed bedrock at the water’s edge with clay on the backshore slope. Bank disturbance in areas of clay could result in localized erosion and/or bank instability.

The construction area for the overflow weir will be dewatered behind a cofferdam throughout the duration of construction in that area (first the east shore, then the west). This will provide the opportunity to ensure that banks are stable before the cofferdam is removed and the area is exposed to river flow. At the intake, work will be mostly above the normal water level, and side slopes within the intake will be graded to stable angles and protected from erosion (where required). Similarly, side slopes in the powerhouse area will be stabilized during the construction process to ensure that they are stable and not prone to erosion.

Shoreline stability will be ensured through compliance with the sediment and erosion control plan (Section 5.3.2.1). Monitoring of shorelines will be conducted throughout the construction period to assess stability and the requirement for remedial measures (see Section 9 – Environmental Monitoring Programs). Any bank areas disturbed during construction will be stabilized as quickly as possible with native plant material or other bioengineering/structural methods (e.g., riprap).

5.3.2.5 Soil Contamination Soil contamination could occur due to accidental spills6 (e.g., due to improper handling and storage of chemicals, or due to unanticipated events such as equipment leaks) of pollutants7

6 A spill is defined in the Ontario Environmental Protection Act as “a discharge into the natural environment, from or

out of a structure, vehicle or other container, that is abnormal in quality or quantity in light of all the circumstances of the discharge: (MOE, 2007b).

such as fuels, lubricants, paints, solvents, form oils and other chemicals associated with the construction process. The contractor will be required to develop and enact spill prevention and contingency plans prior to commencement of construction activities at the site. The plan will specify roles, responsibilities and appropriate procedures for chemical handling, spill

7 A pollutant is defined in the Ontario Environmental Protection Act as a “contaminant other than heat, sound, vibration or radiation”, where a contaminant is defined as “any solid, liquid, gas, odour, heat, sound, vibration, radiation or combination of any of them resulting directly or indirectly from human activities that causes or may cause an adverse effect” (MOE, 2007b).


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response, reporting and cleanup, with reference to relevant legislative requirements. In addition, any spills must be reported to MOE’s Spills Action Center 1-800-268-6060.

5.3.3 Air Quality and Noise Air quality refers to the chemical composition of the air. A negative effect is considered to be an increase in the concentrations of airborne pollutants such as fine particulate matter (e.g., dust) or other chemical pollutants that would adversely affect human health, local wildlife and/or vegetation. Work activities that could affect air quality during the construction phase include:

• exposure of soil (e.g., vegetation removal, soil excavation, stockpiling),

• rock crushing or drilling activities,

• vehicle and equipment travel on access roads and in working areas,

• equipment and vehicle use and corresponding air emissions, and

• burning of vegetation/clean wood waste.

It is not anticipated that the construction process will contribute to the formation of fog, thermal effects on air, icing or micro-climate. Therefore, these potential effects are not discussed in this section.

Impacts on air quality during the construction phase could occur due to fugitive dust emissions, emissions of combustion by-products from equipment and vehicle use and/or the burning of waste.

Fugitive Dust There are no permanent residents in proximity to the project area (Ear Falls is located 30 km away). Dust from vehicle traffic on South Bay Road (gravel surface) is anticipated to be the largest source of fugitive dust emissions associated with the project. No significant generation of dust from vehicle traffic on site access roads is expected (short, and vehicles will travel at slow speeds). Drilling, blasting and rock crushing at the site will also generate some fugitive dust.

There are no human receptors in the vicinity of the project. Fugitive dust could adversely affect surface water quality and aquatic habitat if it were to be deposited in watercourses in sufficient quantity. Extremely high levels of dust may also result in the smothering of vegetation, which results in mortality as it blocks photosynthesis and/or increases susceptibility to disease. This is of particular concern along main travel roads (South Bay Road), where roadside vegetation may be subject to dust smothering.

Mitigation measures to be used, as required, to control dust include:

• use of dust suppression on exposed areas including road surface, stockpiles and works/laydown areas,


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• if required, dust suppression will be with water or non-chloride based chemical dust suppressants. If water is withdrawn from the river for dust suppression purposes at a rate >50,000 L/d, a PTTW from the MOE will be required,

• hard surfacing of heavy machinery working pads and parking areas,

• phased construction, where possible, to limit the amount of time soils are exposed, and hence, susceptible to wind-generated erosion,

• earth-moving works not to be conducted during excessively windy weather. Stockpiles to be worked (e.g., loaded/unloaded) from the downwind side to minimize wind erosion,

• stockpiles and other disturbed areas to be stabilized as necessary (e.g., tarped, mulched, graded, revegetated or watered to create a hard surface crust) to reduce/prevent erosion and escape of fugitive dust,

• blast mats, utilized during blasting activities to control fly rock, will also help to control the release of airborne dust,

• dust curtains to be used on loaded dump trucks delivering dust-prone materials to and from off site, and

• workers to utilize appropriate personal protective equipment (e.g., masks, safety goggles).

Mitigation measures such as dust suppression or hard surfacing will be implemented if dust generation becomes a problem, based on visual assessment of the construction site by the site inspector (or his delegate).

An Environmental Compliance Approval will be required for the operation of a rock crusher. Dust and other emissions from the crusher will need to be assessed and meet with regulatory requirements for the Approval. The application will be submitted once the details of the crusher have been determined (i.e., type, operational capacity, location, etc) during the detailed design process, and will specify mitigation and monitoring required to ensure that air and noise emissions meet provincial requirements.

It is anticipated that, with the implementation of appropriate mitigation measures, adverse impacts on air quality due to fugitive dust will be localized in the construction area, low magnitude and short term in duration.

Combustion By-Products A variety of construction, haulage and personnel vehicles will be used on site during the construction period. Use of such equipment will result in the release of combustion by-products, including carbon monoxide, nitrogen oxides and sulphur oxides. This will deteriorate local air quality in the immediate vicinity of the emission source.

The relatively small size of the workforce and the corresponding small increase in localized airborne contaminants anticipated due to vehicle/equipment exhaust levels will not result in any measurable change in regional air quality. The effect is not anticipated to be measurable beyond 500 m from the project, will be temporary, very low in magnitude and localized in the


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construction area. As a BMP, vehicles should be run only when necessary and exhaust equipment (e.g., pollution control devices) inspected regularly. The contractor is encouraged to limit idling of construction equipment to periods of no longer than 5 minutes, although exceptions will occur when idling is required to provide heating or to avoid cold starting.

Waste Burning The burning of slash has the potential to affect local air quality. Slash is the accumulation of miscellaneous residue such as tree tops and limbs that are left over from timber harvesting and forest clearing. Only slash that cannot be chipped will be incinerated on site, as smaller pieces will be chipped and utilized during site restoration. The remaining slash not suitable for chipping is to be placed in manageable piles and either incinerated on site during safe burning conditions, in accordance with an MNR burn permit, or allowed to naturally decompose. Some particulate matter will be emitted to the air that may result in exceeding the expected baseline maximum 24-hr concentrations (22 ppb; Hoffer 1990) for Total Suspended Particulate (TSP), but the affected area will be small and localized, and the disturbance will be temporary. Appropriate safeguards and precautionary measures will be employed during burning. Burning will not be conducted within 120 m of the Trout Lake River in order to minimize the potential for deposition of ash within the river. No other wastes, including municipal, domestic or construction wastes, are to be burned.

The Contractor is required by MNR and the Forest Fires Prevention Act to have on hand appropriate fire suppression equipment. In addition, the contractor must develop communications, notifications and reporting protocols, as well as initial response procedures. All mechanical equipment shall be equipped with spark arrestors and be kept free of any accumulation of flammable materials.

Noise and Vibration Construction activities such as blasting and heavy equipment use can generate high levels of noise and vibration which may adversely affect sensitive receptors within 1000 m of the work area. The closest receptor to the area is a trapper cabin that is located 1.2 km downstream and to the southwest. Given the distance to this receptor and prevailing wind direction being westerly, no adverse effect is predicted. Construction equipment will comply with the relevant MOE NPC guidelines for emissions from equipment. Standard muffling devices will be used on equipment.

5.3.4 Groundwater Infiltration of groundwater into the intake channel, intake structure, penstock, powerhouse and tailrace excavations may result in temporary, localized alterations in groundwater flow and level as it is pumped/removed from these areas. There are no known uses of groundwater locally, and these would be short-term temporary events. It is not anticipated that this will have an impact on the overall groundwater resources in the local area.

Groundwater quality could be impacted by accidental spills during the construction phase if pollutants infiltrate the soil and/or bedrock to the water table. Mitigation measures discussed in Section 5.3.2.5 to prevent/minimize impacts on soils due to accidental spills would assist in preventing/minimizing impacts on groundwater as well. These mitigation measures are


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anticipated to be effective in minimizing the magnitude, geographic extent and duration of any spills that do occur. Therefore, the likelihood of a spill being large enough to infiltrate to the groundwater table is low. Monitoring will be conducted throughout the construction period to ensure that the contractor is adhering to the terms and conditions of the EA, tender specifications and relevant permits and approvals, and that mitigation measures are having the intended end result (i.e., preventing/minimizing the potential for spills and associated groundwater impacts).

5.3.5 Surface Water Hydrology and Hydraulics Facility Construction Construction activities will result in minor changes to local water levels and velocities within the project area. Temporary diversion structures (i.e., cofferdams) will shift the main flow path first to the west side and then to the east side of the river at the overflow weir location as the structure is constructed (see Figure 5.1). Velocities within the diversion areas are anticipated to be higher and upstream levels may be slightly higher as flow is passed through a narrower opening. Flow distribution through the falls (i.e., into the North and South channels) will not be affected during this period.

As noted in Section 2, construction of the powerhouse, a portion of the tailrace and the entire intake channel, intake structure and penstock component of the facility will proceed in the dry behind plugs that will be retained at the shoreline. Excavation of the tailrace will occur in the wet behind silt curtains with no cofferdam. No effect on hydrology and/or hydraulics will occur during the approximate 12 months required to complete those works.

As discussed in Section 2, construction of the overflow weir will proceed in a phased manner during the seasonal low flow period. Phase 1 will involve construction of a cofferdam around the proposed diversion sluiceway on the left (east) bank, which extends far enough upstream to allow the training wall to be constructed and far enough into the river to allow the sluiceways and a portion of the overflow weir to be built. Excavation of the river bottom in front of the sluiceway is required to provide adequate flow passage capacity. The Phase 1 cofferdam will be in place for an 8-month period, subject to final construction scheduling.

Once the diversion structure is complete, the Phase 1 cofferdam will be removed and work will begin on the installation of the Phase 2 cofferdam (west side). Access to the west side of the river will be over the diversion structure. As the cofferdam is installed, river flow will transfer to diversion sluice, and the Phase 2 cofferdam will be completed upstream and downstream from the work area. This will allow the work area to be dewatered and construction to proceed in the dry.

Some low magnitude, short-term alteration of the flow rate of the river may occur as the Phase 2 cofferdam is installed until the entire river flow is diverted through the diversion sluiceway. No overall change to river hydrology would occur as a result of this activity. Hydraulics in the Big Falls reach immediately downstream from the diversion sluice will be altered since all flow will be entering the reach from the east side of the river instead of being spread across the full river width/cross section. This will result in low magnitude, localized changes in flow velocity, vector and wetted surface area in the upper reaches of the falls, and


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may result in more flow being directed into the North Channel for the duration of this diversion. It is anticipated that construction of the remainder of the overflow weir (i.e., requirement for Phase 2 diversion), will require approximately 5 months.

Changes in local hydrology (i.e., surface runoff rate and vector and water storage patterns), may also result from ditching along the new access roads, vegetation clearing, land grading and the increase in impervious surfaces at facilities during construction. These activities have the potential to somewhat increase the rate and quantity of surface runoff to the Trout Lake River. Mitigation measures (rock-fill check dams, hay bales, in-line sediment traps, etc) will be used to address these potential adverse effects. Given the very small affected area and the implementation of effective mitigation, these changes are considered to be very low magnitude.

Head-Pond Filling Head-pond filling will be accomplished by restricting flow through the sluiceway structure. Flow will be restricted by no more than 10% of the flow rate occurring in the river during the filling period. For example, if river flow is at the annual average flow (16.8 m3/s), flow in the river will be restricted by no more than 1.68 m3/s to minimize adverse effects on downstream hydrology. At this rate, head-pond filling will take approximately 3 days, adding approximately 428,000 m3 to the head-pond volume. Therefore, a short-term low magnitude effect on downstream river hydrology will occur due to flow restriction during head-pond filling. Once the head pond is filled, the hydrology of the river will remain unchanged. Therefore, head-pond filling will only have a very minor short-term impact on river hydraulics. Head-pond filling will also result in changes to river hydraulics as the cross sectional area of the river channel upstream from the overflow weir increases and flow velocity decreases. The filled head pond will extend approximately 1.7 km upstream, and water levels immediately upstream of the new dam will be elevated by approximately 4 m to the FSL of 368.77 m. This will increase the surface area of the reach from the new overflow dam to the upstream end of the head pond from approximately 9.5 ha (surface area of existing river channel) to approximately 15.8 ha (river channel plus cleared shoreline area). These changes in hydraulics will occur over a short time period as the head pond is filled. Once the FSL is reached, the hydraulics of the river through the head pond will be permanently altered as per the long term operational regime of the facility. The discussion of changes to river hydrology and hydraulics as a result of facility operation is presented in Section 6.

5.3.6 Surface Water Quality Construction activities have the potential to adversely affect surface water quality by increasing turbidity (associated with the release of soils into the watercourse or mobilization and downstream transport of existing sediments),by increasing metal and/or nutrient concentrations, and/or by accidental discharges of pollutants such as fuels, lubricants and other hazardous materials. Surface water quality could also be affected by construction debris, sewage effluent, use of treated wood products, releases of alkaline cement leachate and acid rock drainage.

No treated wood products are expected to be used during the construction process. Also, no human sewage effluent will be released as portable toilets will be provided at the site.


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Therefore, the potential effects on surface water quality, in the absence of mitigation, could include:

• increased turbidity due to erosion and sediment transport,

• increased concentrations of metals and nutrients due to erosion and sediment transport,

• increased pH due to use of concrete and grout,

• increased ammonia due to blasting residues,

• increased concentrations of construction debris, and

• decreased pH and increased metal leaching due to acid rock drainage.

There is also a risk of potential negative effects on surface water quality due to accidental spills during construction. Surface water quality could also be adversely affected by deposition of fugitive dust generated from the construction site, which could result in increased turbidity. Mitigation measures to prevent/minimize fugitive dust (Section 5.3.3) are anticipated to be effective in minimizing the potential for dust deposition in the watercourse.

5.3.6.1 Turbidity from Erosion and Sediment Transport Construction activities could increase the rate and/or quantity of sediment transported to or within local watercourses (i.e., the Trout Lake River and/or the local drainage network) including:

• activities associated with new access road construction (e.g., vegetation clearing/ grubbing, stockpiling of slash, grubbed material or road base materials, ditching, and placement of road base/work area materials);

• clearing and removal of vegetation at the overflow weir, intake and powerhouse areas and along the new transmission line and access road ROWs;

• stockpiling of soil associated with excavation and clearing activities;

• blasting and excavation during construction of the intake and tailrace channels;

• cofferdam installation and removal of the overflow weir; and

• dewatering operations head-pond clearing and exposure of terrestrial soils to erosive forces of water flow.

Mitigation measures to be followed by the contractor during construction to minimize the potential for adverse environmental effects associated with erosion and transport of sediment include:

• an approved sediment and erosion control plan will be developed by the contractor to define proper construction methods and prepare for unexpected occurrences (see Section 5.3.2.1),

• construct all roads according to MNR’s ‘Environmental Guidelines for Access Roads and Water Crossings’ (MNR, 1990),


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• where possible, vegetated buffer strips greater than 15 m wide should be maintained between construction areas and watercourses,

• cofferdams will be used at the overflow weir location to allow construction to proceed “in the dry” to minimize the disruption and release of riverbed sediments,

• cofferdam dewatering activities will transfer seepage water from the work areas to temporary on-site settling pond(s) constructed in accordance with a CofA for Industrial Sewage (MOE),

• only clean material should be used for rock-fill cofferdams (e.g., pre-tested, washed or otherwise certified as being free of fine sediment and acid-generating constituents),

• rock-fill cofferdams should be installed in the river channel as quickly as possible such that the amount of fine sediment (from the river bottom) being washed downstream is minimized (if flow velocity is sufficient to mobilize cofferdam material),

• use of impermeable geotextile membranes in cofferdams is preferable to use of silt, clay, till or other loose materials such as loam, organic soil and vegetation in order to prevent seepage of water through the cofferdam or downstream transport of fill materials during cofferdam installation,

• spill response and emergency equipment and material (e.g., fill for cofferdams, gravel bags, oil absorbents) should be kept in close proximity to cofferdams, such that repairs can be conducted quickly to prevent erosion and transport of sediments from the dewatered working area behind the cofferdam, and

• all cofferdam material should be removed from the riverbed and reused elsewhere or properly disposed of upon decommissioning of the cofferdam. No cofferdam material should be discarded within the watercourse or on the riverbanks, unless otherwise approved by MNR and DFO (e.g., for shoreline stabilization or aquatic habitat enhancement).

The contract documents will reference and/or incorporate environmental protection standards for construction work in and along waterbodies, including:

• Ontario Provincial Standard Specifications (OPSS) 577 – Construction Specification for Temporary Erosion and Sediment Control Measures,

• OPSS 182 – General Specification for Environmental Protection for Construction in Waterbodies and on Water Body Banks,

• OPSS 517 – Construction Specification for Dewatering, and

• OPSS 518 – Construction Specification for Control of Water from Dewatering Operations.

It is anticipated that development of an effective sediment and erosion control plan which includes the above-noted mitigation measures in conjunction with diligent construction monitoring will eliminate adverse effects on local surface water quality. It will be the responsibility of the contractor to monitor the sediment and erosion control devices and local


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surface water quality conditions during construction and take appropriate actions if unacceptable levels of turbidity are observed (see Section 9.2 – Construction Phase). Work activities may need to stop until corrective measures can be taken to control releases, so as to prevent any adverse effects.

5.3.6.2 Metals and Nutrients An increase in erosion of soil and/or transport of soil particles into a watercourse could potentially increase the concentrations of metals or nutrient in the watercourse if metals or nutrients are bound to the soil particles and then mobilized into the water column. This could result in an increase in the concentration of metals or nutrients in the water column, with adverse effects on water quality.

Mitigation measures described above to eliminate erosion and sediment transport from terrestrial and aquatic environments during construction will mitigate this potential adverse effect on water quality.

5.3.6.3 Concrete and Cement Use Concrete, grout and associated materials (e.g., cement, mortars) typically have high pH values (i.e., highly basic or alkaline), which, if they enter a watercourse, could create conditions that are toxic to fish (Province of British Columbia, 2007). Concrete will be used in the construction of weirs, the powerhouse (behind cofferdams) and the intake structure and will not be directly exposed to surface water in Trout Lake River. However, precipitation falling within the cofferdam area does have the potential to come into contact with concrete and grouting products during construction. Water accumulating within the cofferdam areas will be pumped out to the settling pond. If this water does have high pH, it will be treated prior to discharge to Trout Lake River.

There are a number of construction BMPs to prevent adverse impacts on surface water quality and biota due to the use of concrete (Province of British Columbia, 2007). They are as follows:

• pre-cast structures will be used, where possible, to minimize the use of concrete on site,

• no alkaline cement products will be deposited directly or indirectly into or adjacent to any watercourse,

• concrete materials that are cast in place will remain inside formed structures, isolated from the flow of any watercourses until fully cured (i.e., a minimum of 48 hours if temperature is above 0°C or a minimum of 72 hours if air temperature is below 0°C),

• a designated concrete truck rinsing facility will be established at the site. All wastewater arising from truck rinsing will be contained, treated in the settling pond to meet pH requirements and discharged back to the river. An Environmental Compliance Approval will be obtained from MOE as required.

• the pH of the Trout Lake River immediately downstream from the work site will be monitored through the duration of the overflow weir construction period. If pH values change more than 1 pH unit from background concentration, measures will be


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implemented to assess the source of alkalinity and prevent further releases from occurring.

• the pH of settling pond discharge water will be monitored on a regular basis to ensure it remains within the MOE limit (6.5 to 8.5). If pH is found to be outside the allowable limit, a contingency plan would be implemented (see below).

• cement bags are to be stored indoors, where possible. If outdoor storage is required, cement bags should be covered with waterproof sheeting and raised from the ground surface (e.g., on wooden palates) to ensure no contact with surface water runoff. Impervious material will be placed under the elevating mechanism to collect any spills (e.g., due to ripped bags). Empty cement bags are to be collected as soon as possible after use and spills of cement or concrete cleaned up as appropriate.

Monitoring will be conducted throughout the construction period to ensure that the contractor is adhering to the terms and conditions of the EA, tender specifications and relevant permits and approvals, and that the mitigation measures are having the intended outcome. If elevated pH is an issue in the settling pond(s), the following contingency plans will be implemented:

• At the first occurrence of high pH (during monitoring) dilute acid will be mixed into the discharge flow into the settling pond to neutralize high pH levels. Acid for use would be maintained on site throughout the duration of settling pond use.

• If high pH is a continuing issue with the settling pond discharge, the contractor would use a tanker truck to pump CO2 into the settling pond to neutralize high pH. The piping and distribution system for CO2 injection would be considered during the detailed design such that any infrastructure required to distribute the CO2 would be planned during the design.

With these contingency plans in place, high pH would be quickly neutralized to ensure no adverse effects on surface water quality at the settling pond discharge location.

5.3.6.4 Ammonia Due to Blasting Residues If Ammonia-Nitrate Fuel Oils (ANFO) are used during blasting operations, the residue, if transported into surface water could either directly or indirectly (via settling ponds) result in an increase in ammonia levels, which if high enough, could be toxic to aquatic biota. Therefore, non ANFO-based blasting products will be used to prevent water quality issues associated with blasting residues.

5.3.6.5 Construction Debris Construction waste such as metal debris, sawdust, concrete cuttings/debris and other fine waste materials could potentially be transported into surface waters. In order to prevent this occurrence, the contractor is required to adequately contain all debris materials within the construction area, and remove all debris as soon as possible to prevent movement into watercourses or the surrounding environment.


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5.3.6.6 Acid Rock Drainage Excavated rock will be reused around the construction site where possible (e.g., road base, work and laydown areas, riprap). Acid generation occurs when rock containing sulphide and elemental sulphur are exposed to the weathering effects of oxygen and water. Acidity is generated from the oxidation of sulphur and precipitation of ferric iron. Acid rock drainage (ARD) occurs when the resulting acidity is entrained by water. If ARD were to occur, it could potentially impact water quality of receiving waterbodies, resulting in more acidic conditions, with corresponding effects on aquatic biota, depending on the magnitude of pH change.

The proposed site is located within an area of Precambrian rock consisting of several main rock types including granitic and volcanic rocks around the Big Falls area. The potential for acid rock drainage from the granitic rock type, consisting primarily of diorites and granodiorites is generally low since these minerals are alumino-silicate based, and typically do not contribute to forming acid conditions. The potential for acid rock drainage from the volcanic rock types, consisting primarily of felsic to intermediate volcanic rocks is lower to intermediate. In addition, as with all rock masses, given the variability with depth and surface extent there may be small pockets of slightly different mineralization (e.g., sulphides), which may be leachable and have a very small contribution to forming acidic conditions.

The bedrock in the project area has not been tested for ARD potential at the present time. To assess the potential for ARD, samples of bedrock from the excavations will be collected and submitted for a modified acid base accounting (ABA) test on the start of construction (see Section 9.2 – Construction Phase). The sampling and testing or excavated rock will follow protocols recommended by Environment Canada, namely:

• representative sampling of rocks to be disturbed will be undertaken using an appropriate sampling protocol,

• leachate potential and net acid generating potential will be assessed on representative samples by an accredited laboratory, and

• an assessment of the potential impacts of ARD on surface water quality will be made following receipt of the test results.

Should these samples reveal a high potential for acid generation potential, appropriate plans will be developed, in consultation with regulatory authorities to deal with this situation. Generally accepted industry standard mitigation measures typically involve disposing of rock with ARD potential in an engineered containment structure with a drainage collection system to prevent potentially acid drainage from freely infiltrating the soil into groundwater or leaving the containment area via overland flow. The drainage collection system could potentially funnel all drainage through a reactive barrier wall to neutralize acid constituents prior to release from the containment structure. This is one conceptual method of addressing potential ARD issues.

5.3.6.7 Treated Wood No treated wood is anticipated to be used in or near water during construction. No wooden penstocks, wooden bridges or wooden in-water structures will be required. If treated wood is


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used on site during construction, the following mitigation is recommended to prevent leaching of toxic materials to the surrounding watercourse:

• use non-arsenic, non-chrome based treated wood in accordance with Canadian Standards Association (CSA) standards,

• clean up sawdust and wood debris from any treated wood immediately after generation and dispose at an approved location,

• do not burn pressure-treated wood at site, and

• seal pressure-treated wood with paint, stain or sealant.

5.3.6.8 Fuels, Lubricants and Other Hazardous Materials Fuels, lubricants and other hazardous materials will be used at the site throughout the duration of the construction period. Activities during the construction phase that could potentially result in transport of these materials to the watercourse, with subsequent adverse effects on water quality, include:

• refuelling and maintenance (e.g., oiling, addition of hydraulic fluid) of equipment (e.g., accidental spills, improper disposal of waste fluids),

• use of equipment containing fuels, lubricants or other materials within, or in the vicinity of watercourse (e.g., leakage from machinery, washing of materials from surface of machinery), and

• storage of hazardous materials, including cement (e.g., accidental spills, leaching and/or runoff of materials).

Mitigation measures to be followed by the contractor during construction to minimize the potential for adverse environmental effects associated with the storage, use and disposal of fuels, lubricants and other hazardous materials include the following:

• Establish designated refuelling and maintenance areas at least 5 m from flowing watercourses and away from drainage ditches, channels or other wet areas. The refuelling of small equipment (e.g., Airtrack Drills, compressors and lighting) will be undertaken on site (behind cofferdams) with a small service truck equipped with a spill kit.

• Locate designated hazardous material storage areas at least 10 m away from watercourses, for all hazardous materials to be stored outside. Storage areas should be above ground and enclosed by an impervious secondary containment structure (e.g., berm or container) capable of holding the entire volume of the stored material, as well as some additional volume of rainwater. Bermed areas are to be pumped out as required to remove accumulated precipitation. Pumped liquids are to be properly disposed of by a licensed hauler. Bermed areas are to be monitored throughout the construction period to ensure their integrity. The contractor will be instructed to consider the guidance provided in MOE’s Guidelines for Environmental Protection Measures at Chemical and Waste


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Storage Facilities (MOE, 2007c) during design of temporary material storage areas for use during the construction process.

• Only machinery/equipment that is clean and well maintained (e.g., no leaks or fluid residue on surfaces) is to operate near watercourses or drainage areas. No equipment is to be operated directly within watercourses, except with MNR, MOE or DFO approval of the in-stream works (i.e., cofferdam installation and removal). Backhoe buckets are to be cleaned prior to use in the watercourse. No washing of equipment is to take place within or near watercourses.

• A barrier will be erected around the storage area to prevent accidental damage to containers.

• Provide adequate spill clean-up materials/equipment (e.g., absorbents) on site. The contractor will prepare a spill clean-up procedure/emergency contingency plan, prior to commencement of work at the site. The plan will be forwarded to relevant agencies prior to commencement of works on site.

• Any accidental spills likely to cause the following impacts should be immediately reported to the Ontario Spills Action Centre (1-800-268-6060):

impairment to the quality of the natural environment - air, water, or land,

injury or damage to property or animal life,

adverse health effects,

safety risk,

making property, plant, or animal life unfit for use,

loss of enjoyment of normal use of property, or

interference with the normal conduct of business.

(Source: Queen’s Printer for Ontario, 2007).

It is anticipated that implementation of these mitigation measures in conjunction with construction monitoring will be effective in reducing the potential for spills. However, as with all construction projects where potentially contaminating fluids are used, the potential for accidents and other unforeseen events possibly leading to a spill will remain throughout the duration of the construction period. These mitigation measures are anticipated to be effective in minimizing the magnitude, geographic extent and duration of any spills that do occur.

5.3.7 Aquatic Habitat Aquatic habitat refers to the physical conditions of the aquatic environment (e.g., substrate, woody debris, channel bed topography, shoreline topography, in-stream vegetation, riparian vegetation, flow velocity and vector) that provide habitat for aquatic biota, including fish and benthic invertebrates. Critical aquatic habitat supports biological functions that are necessary to maintain existing levels of biological productivity (e.g., benthic invertebrate biomass, fish biomass and growth). Types of critical habitat include specialized spawning areas (e.g.,


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cobble shoals used for Walleye spawning), nursery areas and significant foraging habitats (e.g., foraging areas at base of rapids where fish may seasonally congregate to forage and/or spawn).

Changes in aquatic habitat have the potential to increase or decrease the suitability of that habitat to support specific species (i.e., some habitats may not be suitable for some species) and/or to increase or decrease productivity within that habitat patch (i.e., benthic invertebrate biomass per m2 of habitat). Significant negative changes in habitat could result in the loss of some species from that area or a decrease in productivity resulting in decreased fish populations.

During the construction phase, impacts to aquatic habitat could result from:

• in-stream construction associated with:

cofferdam installation/removal and associated dewatering,

tailrace excavation,

• near-shore construction:

clearing, grading and excavation for powerhouse, intake channel and overflow weir,

head-pond vegetation clearing,

• changes in flow or water level associated with:

diversion requirements,

head-pond filling,

• blasting in or near water,

• sediment transport and deposition, waste debris (e.g., sawdust) or toxic chemicals.

Mitigation measures to address fugitive dust and water quality issues were discussed in Sections 5.3.3 and 5.3.6, respectively. It is anticipated that implementation of appropriate mitigation, as identified in those sections, will prevent or minimize impacts on aquatic habitat. Monitoring will be conducted throughout the construction period to verify that mitigation measures are implemented as specified, are having the desired effect, and that no unanticipated impacts are occurring (see Section 9.2 – Construction Phase).

The remainder of this section discusses the potential effects of construction activities on aquatic habitat. The potential effects include:

• temporary loss of aquatic habitat due to cofferdam installation and dewatering,

• permanent loss of aquatic habitat within the footprint of the overflow weir,

• alteration of aquatic habitat at the entrance to the intake and within the tailrace channel, and

• alteration of aquatic habitat during head pond preparation and filling.


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Effects of aquatic habitat alterations on specific aquatic biota (i.e., lake whitefish and walleye) are discussed in Section 5.3.8.

5.3.7.1 In-stream Construction In-stream construction activities (e.g., cofferdam placement/removal, machinery tracking, placement of permanent structures, excavation for tailrace channel) have the potential to directly affect aquatic biota (e.g., fish, benthic invertebrates) by temporary and permanent disturbance and/or loss of habitat, by the creation of barriers to movement, or by impacting habitat suitability during sensitive life stages. MNR’s Northwest Region timing restrictions for in-stream construction activities state that in-water work shall not be conducted from September 15 to June 20, in order to protect the fall lake whitefish reproductive period and the spring walleye reproductive period (i.e., spawning, egg incubation, and immediate post hatch fry development) in the Trout Lake River. This timing restriction will also protect the reproductive period of northern pike, white sucker and other small forage species within the study area.

In-water construction activities predominantly include the installation and removal of cofferdams used to isolate the overflow weir work sites, tailrace excavation and removal of the rock/earth plugs at the tailrace. Therefore, these in-water construction activities must be conducted between June 21 and September 14 unless otherwise approved by MNR/DFO. Adherence to this timing restriction will ensure that there is no disruption to fish, eggs or early-phase larvae during the sensitive reproductive period. Monitoring will be conducted throughout the construction period to verify that contractor strictly adheres to this timing restriction (see Section 9.2 – Construction Phase).

5.3.7.2 Loss of Aquatic Habitat Due to Cofferdam Installation and Dewatering Construction of temporary cofferdams and associated dewatering within the isolated work area has the potential to result in an adverse impact on aquatic habitat due to loss of habitat area within the footprint of the cofferdam and dewatered area. Cofferdams will be installed in two phases, with the first phase being along the east shore to allow construction of the section of the weir that contains the flow diversion structures. During Phase 2, flow will be diverted through these sluiceways, and cofferdams will be installed on the west side of the river to complete the construction of the overflow weir.

Phase 1 and 2 Cofferdams at the Damsite The Phase 1 cofferdam will be constructed around the proposed diversion sluice work area on the left (east) bank at the proposed overflow weir location. It will begin on the east shoreline 50 m above the weir location, extend 35 m into the river, and extend 20 m downstream (see Figure 5.1). This work area will allow the sluiceways, upstream training wall and a 45 m segment of the overflow weir to be built. The footprint of the structure will cover 1500 m2 on the river bottom and east shoreline, and will be constructed to a crest elevation of 367.4 m, which provides adequate freeboard for a 1:20-yr flow event. It is anticipated that the cofferdam will be installed in July and removed in September of Year 1. The cofferdam and dewatered area between them will occupy a footprint of approximately 2700 m2. The footprint of both the cofferdam and dewatered work area is located in an area of high velocity rapids (~ 2 m/s) at the crest of the falls. Substrate in the area is dominated by


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bedrock and large boulders with isolated pockets (<5% of total area) of smaller particles (cobble). Two benthic sampling areas (near-shore locations that could be accessed by wading and pockets of smaller particles that could be sampled for invertebrates) were located just below this work area. Locations USB3 and USB4 consisted of 20 to 60% bedrock, 20 to 40% boulder, and 20 to 40% cobble (Hatch, 2011e).

The area downstream from the cofferdam also consists of high velocity rapids at the crest of the falls dominated by bedrock and large boulders, with similar habitat values. The downstream falls/rapids are an impassable barrier to upstream fish movement.

The Phase 2 cofferdams will extend across the west half of the river and will isolate the remainder of the overflow weir work area to allow construction to proceed in the dry. The Phase 2 cofferdam will connect to the west end of the new section of overflow weir (that contains the flow diversion structure). It will begin on the west shoreline 60 m above the weir location, extend 60 m across the river to the newly completed weir section, and extend 20 m downstream (see Figure 5.1). The footprint of the structure will cover 1400 m2 on the river bottom and west shoreline, and will be constructed to a crest elevation of 368.9 m, which provides adequate freeboard for a 1:20-yr flow event. It is anticipated that the cofferdams will be in place for 8 months, and will be installed in early September Year 1 and removed after June 20, Year 2. The cofferdam and dewatered area between them will occupy a footprint of approximately 2900 m2. The affected footprint will be in an area of high velocity rapids (~ 2 m/s) dominated by bedrock and large boulders with isolated pockets of smaller particles (<5% of total area) scattered within the larger area, and mostly adjacent to the shoreline. Two benthic sampling areas (near-shore locations that could be accessed by wading and pockets of smaller particles that could be sampled for invertebrates) were located just below this work area. Locations USB1 and USB2 consisted of 60 to 80% bedrock and 20 to 40% cobble (Hatch, 2011e).

The cofferdams and dewatered area will result in the loss of aquatic habitat for benthic invertebrate and fish use and will result in a decrease in local productivity, and benthic invertebrates within the footprint of the cofferdam structures/dewatered area will be lost. However, Trout Lake River immediately downstream from the work area contains an abundance of similar habitat types (as well as rapids in the upper portion of the proposed head pond) which will continue to provide this function. While overall aquatic habitat (primarily benthic invertebrate production) in this section of the river will decrease somewhat as a result of this habitat loss, no measurable effect on fish productivity is predicted. Any fish found within the area during dewatering operations will be collected and transferred to the upstream reach (see Section 5.3.8).

5.3.7.3 Permanent Habitat Loss within Footprint of Overflow Weir The construction of the overflow weir will result in a permanent loss of aquatic habitat within its footprint area (approximately 520 m2 at the crest of Big Falls). The weir’s footprint will be in an area of high velocity flow (~ 2 m/s) dominated by bedrock and large boulders with isolated pockets of smaller particles (<5% of total area) scattered within the larger area and along the shoreline. The installation of the weir will result in the permanent loss of aquatic habitat for benthic invertebrate and fish use and will result in a decrease in local productivity,


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and the loss of benthic invertebrates within the footprint of the structure. However, Trout Lake River immediately downstream from the work area contains an abundance of similar habitat types (as well as rapids in the upper portion of the proposed head pond) which will continue to provide this function throughout the construction process. While overall aquatic habitat (primarily benthic invertebrate production) in this section of the river will decrease somewhat as a result of this permanent habitat loss, no measurable effect on fish productivity is predicted. Any fish found within the area during dewatering operations will be collected and transferred to the upstream reach (see Section 5.3.8).

5.3.7.4 Altered Habitat at the Intake Entrance and in the Tailrace Channel As noted in Section 2 (Subsections 2.1.2 and 2.1.3), the intake channel and a portion of the tailrace channel will be constructed in the dry behind a rock/soil plug at the shoreline. The intake channel will transfer flow to the powerhouse once the head pond is filled. The present elevation of the river during the 2-yr flow event is approximately 3765.4 m, while the invert of the intake channel ranges from 366.10 m (at river’s edge) to 365.62 at the intake structure. As such, there is a small chance that the intake work area could be affected by a significant flow event. If the contractor chooses to install a cofferdam at the intake entrance, it will be above the normal river water level. Work at the intake channel will take place within the confines of sediment control devices and will not affect any aquatic habitat at that location.

Work at the tailrace channel will involve excavation into shoreline and the existing river channel to create the path for the transfer of flow back to the lower river. The channel will be 5 m wide at the invert (343.3 m) followed by a 15 m long transition at a 25% slope to the natural riverbed. The altered area is approximately 48 m2 and consists of fine sediments on the river bottom overlaying bedrock with very low velocities under most flow events (even to 2-yr event). Shoreline in the area is predominantly exposed bedrock, with a thin layer of soil and shrubs/small trees near the waterline. Construction of the tailrace is proposed in the wet within the confines of a silt curtain. This disturbance of aquatic habitat during the construction period is not expected to reduce the productivity of the downstream reach.

5.3.7.5 Head-Pond Preparation and Filling Head-pond preparation involves the clearing of trees with a diameter greater than 0.05 m up to the elevation of the crest of the overflow weir (368.8 m el). Downed woody debris will also be removed from the proposed head-pond area to remove a potential source of organic material that could contribute to production of methyl mercury. Removal of shoreline trees will result in a short-term negative effect on aquatic habitat as the trees and overhanging branches provide shading for the local benthic invertebrate and fish communities, while shoreline vegetation provides allochthonous inputs of organic material to the watercourse, provides bank stability, and buffers surface water runoff volume and helps to maintain quality (by filtering runoff water through root systems and by preventing erosion). Removal of this cover will expose the area to increased erosion potential, and reduced functionality in terms of water filtering and retention. The net effects of vegetation clearing will be a minor alteration to the functions provided by shoreline trees including shading, erosion and sediment control, and allochthonous inputs of organic material to the watercourse (which


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provides forage to the benthic invertebrate community). Sediment and erosion control measures to be implemented during shoreline clearing are discussed in Section 5.4.1.1.

Once the head pond is filled, shoreline trees will start to naturally develop and will once again (in 10 to 20 yrs) be present to provide shading and allochthonous inputs, while woody debris within the inundated area and along the new shoreline will provide new aquatic habitat areas, colonization surfaces and a source of nutrients for primary producers. No other net effects to aquatic habitat are anticipated to occur during the head pond preparation activities.

Head-pond filling is anticipated to occur in Year 2. This will result in the conversion of riverine habitat between the weir and the top end of the rapids approximately 1.7 km upstream into a wider, deeper, slower flowing reach. The surface area of this approximately 9.5 ha reach will be increased by approximately 6.3 ha under typical flow conditions, creating a total surface area of 15.8 ha at FSL.

Water depth and flow velocity will also increase in the head pond reach during the filling process. Pre- and post-project flow velocity, water level and water depth at four flow rates (16.8, 24.5, 42 and 117 m3/s, representing the average annual flow, the facility power flow, the 2-yr flow event and the 100-yr flow event) are provided in Section 6.

Water depth in the head pond reach will increase from 0.21 to 0.76 m at the dam location pre-project to 3.9 to 5.1 m post-project, depending on river flow. Water depth will increase by approximately 3 m over the first 700 m of the head pond above the weir (to 6-8 m deep - see Figure 6.5a), and will then change from 0.4 to 2 m over the remainder of the length of the head pond reach pre-project, to 0.4 to 4 m post-project, declining as one moves upstream. At the upper extent of the head pond, pre- and post-project water levels will be the same (see Tables 6.7 and 6.8). Water velocity in the lower 700 m of the head pond presently ranges from 0.2 to 0.3 m/s in the deepest portion of the existing channel (~500 m upstream from weir location) to 1.8 to 2.4 m/s at the proposed weir location and at a second location approximately 580 m upstream (see Figure 6.5b). Post-project water velocities will be substantially lower, ranging from 0.02 m/s to 0.22 m/s within the same 700 m reach.

Based on the physical changes that will occur in the river reach upstream from the proposed waterpower facility, the following changes are anticipated during the head pond filling process.

• Greater and more consistent water depth will provide more deep water refuge habitat for the fish community within the head pond. The head pond will have an increasingly larger surface area as its volume increases.

• Loss of high velocity habitat in the upper 1000 m of the head pond when filling reaches the NOL. This habitat is used in the spring for spawning by white sucker and walleye (spawning confirmed in spring 2008 and 2012).

• During the filling process, riparian zone vegetation (mostly herbaceous, some woody) and remnants of upland forest after clearing (organic forest floor cover and some woody debris) will be inundated. Any small terrestrial organisms (grubs, beetles, etc) present within the area will be lost and are likely to become forage for fish expanding into the


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larger area. Some release of nutrients into the water column is expected, but this is generally a longer term process that will occur during the operational period. Shallow littoral zone areas will be created in locations along the periphery of each head pond, which will be available to various organisms for their life purposes throughout the year. As these areas mature and become vegetated, they will provide significantly more high quality shallow water habitat than was present prior to project development. These areas are expected to provide spawning grounds for Northern Pike and Yellow Perch, high quality nursery grounds for Walleye (the primary recreational and subsistence angling target species within this river system) and other spring spawning species, as well as abundant cover and foraging habitat.

During head-pond filling, flow in Trout Lake River will be restricted by approximately 10%. At this filling rate with the average annual flow of 16.8 m3/s, the head pond will take approximately 3 days to fill. Higher river flows would allow the head pond to be filled in a shorter time period.

The accumulation of water within the head pond during filling will result in a small reduction in downstream flows. Water levels, flow velocity and the corresponding wetted area will decrease by a small amount during the period of restricted flows, but a 10% reduction in flow is minor and well within the range of natural variability. In addition, the reduction in flow will occur over a very short time period (3 days at the annual average flow rate). During head-pond filling, the majority of flow in the river will pass through the facility or over the weir, depending on the flow rates in the river at the time of filling. Based on the low magnitude and the short-term nature of this event, head pond filling will not have a measurable effect on aquatic habitat in the downstream reach.

5.3.8 Aquatic Biota During the construction phase, direct effects on aquatic biota (e.g., fish, benthic invertebrates) could include:

• physiological or behavioural impacts caused by adverse levels of suspended sediment, waste debris or chemical pollutants in surface waters,

• direct disturbance and/or mortality of biota due to in-stream construction (e.g., cofferdam construction and dewatering, placement of permanent structures), and

• disturbance and lethal or sub-lethal physiological impacts associated with blasting in or near watercourses.

Permanent or temporary changes in aquatic habitat due to project related activities (e.g., temporary cofferdams, water management during construction, structure footprints, head-pond creation) have the potential to impact aquatic biota.

It is anticipated that implementation of appropriate mitigation (as documented in this EA, in contract specifications and as conditions of permits and approvals) will be effective in preventing or minimizing adverse effects on aquatic biota due to air quality and surface water quality impacts (as discussed in Sections 5.3.3 and 5.3.6). However, implementation of mitigation may not be 100% effective in preventing adverse effects on water quality for the


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entire duration of the construction period. However, in the event of an effect occurrence, mitigation as proposed in this EA is anticipated to be effective in limiting the magnitude of such an effect. Therefore, although the potential for adverse effects on aquatic biota due to impaired surface water quality exists, the likelihood of such an effect and the magnitude of effect are both anticipated to be low. Monitoring will be conducted throughout the construction period to verify that mitigation measures with respect to surface water quality are implemented as specified and having the desired effect and that no unanticipated effects are occurring.

The effects of direct disturbance due to in-stream construction and blasting in and/or adjacent to surface water are discussed in the following sections.

5.3.8.1 In-stream Construction Biological sampling in the proposed work area above the falls was undertaken during the low flow event in late September 2011 (Hatch 2011e), and found that the benthic community was dominated by Trichoptera (66.8%) and Ephemeroptera (17.4%) and Diptera (9.1%), with lesser representation by Coleoptera, Bivalvia, Plecoptera, Gastropodia, Hirudinea and Odonata (<2% relative abundance). It should be noted that sampling was undertaken within pockets of smaller particles (cobble, gravel) within the predominantly bedrock substrate in this area, and these results should not be considered representative of the entire area. Productivity in bedrock dominated, high velocity environments is typically lower than the environments sampled. Fish community within the area would be predominantly bottom dwelling species (sculpins, darters and dace) that are adapted to high velocity environments. Larger fish with limited swimming ability (i.e., northern pike) that enter this area would likely be passed over the falls.

In-water construction activities will therefore result in relatively short-term disruption to local fish/benthic invertebrate populations in the vicinity of each work area. However, the work areas do not provide critical reproductive (e.g., spawning habitat) or non-reproductive habitat (e.g., critical foraging areas that are not found elsewhere). Fish within the area will be forced to move to adjacent areas during the cofferdam installation and removal periods and will be restricted from using the habitat within the footprint of the cofferdam and dewatered area during the time that it is in place. No disturbance to fish adjacent to the work area will occur once the cofferdams are in place. The actual in-stream work associated with cofferdam installation and removal is anticipated to be short term in duration, and will be a low magnitude occurrence with no measurable impact on fish productivity.

No mortality of fish is anticipated as a result of the in-stream work associated with cofferdam installation and removal (see Section 5.3.8.2 for mitigation to prevent stranding). Benthic invertebrates under and within the area dewatered behind the cofferdam will perish. No mitigation is possible to prevent this occurrence. Once the cofferdams are removed, benthic invertebrates will recolonize the area above the weir. No significant impact on the benthic invertebrate community is predicted due to cofferdam installation and dewatering.

In-stream work associated with excavation of the tailrace will include mechanical dredging of existing riverbed sediments and potentially blasting of underlying bedrock (if required) (see


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Section 5.3.8.3 for effects and mitigation associated with blasting). During the dredging activities, fish will typically vacate the area due to the in-water disturbance, and invertebrates within the dredged material will likely perish. The tailrace area was not specifically sampled for invertebrate community, but is a depositional area with soft sediments. The benthic community is likely to consist mainly of Oligochaetes (Tubificids), Isopods, Gastropods, Pelecypods and others that live within or on/near the surface of soft sediments. Tailrace excavation will be a low magnitude, short duration event which will be undertaken with appropriate mitigation (i.e., silt curtain installation, clean dredging equipment). This will ensure that there are no significant adverse effects on surface water quality and/or aquatic biota.

5.3.8.2 Dewatering and Stranding Effects Fish and benthic invertebrates could potentially be stranded in the zone behind cofferdams with mortality/injury resulting from entrainment into dewatering pumps or isolation and/or desiccation in dewatered areas. Mitigation to be utilized to prevent injury/mortality to fish during cofferdam construction includes:

• a contingency plan for fish removal will be prepared by the contractor prior to the commencement of cofferdam construction,

• the cofferdam area should be dewatered using a shrouded pump (Clemons Clearwater Screens, Model CW2400 or equivalent screening) to prevent entrainment of fish into the pump, and

• dewatering should occur until the area behind the cofferdam is dewatered to a depth of approximately 0.5 m. Fish should then be removed from the area by netting or electrofishing. Captured fish should be transported immediately to the water body closest to the construction. A License to Collect Fish for Scientific Purposes will be required from the MNR prior to implementation of fish collection and transfer activities.

Implementation of these measures will ensure that there are no long-term adverse effects on fish. Monitoring will be conducted during the cofferdam dewatering period to verify that mitigation measures are implemented as specified above, are having the desired effect, and that there are no unanticipated impacts (see Section 9.2 – Construction Phase).

5.3.8.3 Blasting Blasting in and around water has the potential to result in disturbance, injury or death to aquatic biota (including incubating eggs), or the HADD of aquatic habitat, including impacts on water quality (Wright and Hopky, 1998). Therefore, in order to protect fish and fish habitat, all blasting should be conducted in accordance with the Guidelines for the Use of Explosives in or near Canadian Fisheries Waters (Wright and Hopky, 1998). These guidelines specify that:

• no explosive should be used in or near fish habitat that could produce an instantaneous pressure change greater than 100 kPa in the swim bladder of a fish (appropriate setback distances or charge burial depths are specified in the Guidelines to ensure this is satisfied),


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• no explosive should be detonated if it is likely to produce a peak particle velocity greater than 13 mm/s in a spawning bed during the period of egg incubation, and

• no ammonium nitrate fuel oil mixtures should be used in or near water, as this could potentially result in surface water quality impairment.

To ensure that these requirements are satisfied, the project contract documents will note that prior to implementation of any blasting in or near water, the Contractor will be required to contact DFO with the details of the blasting operation in order to determine applicable approval requirements under the federal Fisheries Act. Monitoring will be conducted during blasting operations in or near water to verify that the overpressure and particle velocity requirements noted above are satisfied. It is anticipated that most blasting will occur outside of the water, on land or behind a cofferdam. Limited in-water blasting may be required to excavate the tailrace. Given this, and the implementation of these mitigation measures described above, only low magnitude, localized disturbance of fish is anticipated due to blasting. No mortality of fish is predicted to occur as a result of blasting.

Marshall Macklin Monaghan (2007) identifies additional mitigation measures to prevent or reduce the impacts of blasting on aquatic biota and habitat. These measures, which will be considered during design of blasting activities, include:

• utilizing alternative excavation methods (such as hoe-ramming) where possible,

• blasting activities in or near water should be conducted within the MNR Northwest Region In-stream Construction Timing Window (i.e., blasting may occur between June 21 and September 14),

• limit energy released by blast charges by avoiding release of energy beyond that required to have desired effect on rock, place stemmed charges in drilled holes as opposed to surficial charges, limit charge size, maintain low particle velocities, in accordance with DFO specifications,

• increase time delays between successive charges and direct force of blast away from fish habitats (e.g., toward land),

• maximize the charge setback distance from watercourses to the greatest extent possible,

• promote fish dispersion from area slated for in-water blasting (e.g., sonic or electric shock or set off scaring charges prior to main blast),

• utilizing methods to minimize turbidity associated with in-water blasting (if required) such as use of turbidity curtains or other methods to cover, shield or enclose blast area, and

• blasting, including initial site surveying, establishment of blasting procedures, recording of blast parameters, monitoring of blasts for vibration and overpressure, should be conducted by a qualified blasting consultant.


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5.3.9 Terrestrial Environment

5.3.9.1 Terrestrial Vegetation Clearing of trees and brush will be required along the new access road, at the laydown/works areas, at the intake, dam, powerhouse and switchyard, along the new transmission line and in the head-pond area. Estimates of the amount of clearing required, as well as an indication of the predominant species to be cleared within each area, are provided in Table 5.2.

The vegetation species and community types to be cleared are typical of the local study area and the Ontario Boreal region in general; no ‘species at risk’ or significant community types have been identified. Clearing is to be conducted according to requirements outlined in approvals/permits to be obtained from MNR. In addition to those requirements, best management practices are to be employed to prevent damage to remaining vegetation communities, such as:

• all areas to be cleared, including the reservoir, are to be clearly identified (e.g., site fencing, flagging tape along the edge of the clearing zone) and all activities of the contractor restricted to those specified work areas,

• in locations where the zone to be cleared is small, such as the upper extent of the reservoir, individual trees to be cleared will be flagged,

• materials disturbed from clearing and grubbing activities are not to be pushed up against remaining vegetation stands,

• equipment and material storage areas and stockpiles will be kept away from residual trees in the study area to prevent damage to root zones due to soil compaction,

• all trees are to be felled into cleared areas to minimize damage to the remaining stand,

• where overhanging trees exist, standard clearing practices are to be employed to minimize the risk of trees falling into the river,

• clearing and grubbing are to be minimized to the greatest extent possible, and

• the existing forest floor vegetation mat is to be left in place wherever possible.


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Table 5.2 Vegetation to be Cleared

Location Area Cleared (ha)

Dominant Vegetation Forms/Species

Temporary Clearing 0.5 Mixedwood Forest (Poplar, Spruce), Riparian shrubland (Red Osier Dogwood)

Permanent Clearing 8.6 New access road 0.5 Mixedwood Forest (Poplar, Spruce) Intake, works, overflow weir

1.1 Mixedwood Forest (Poplar, Spruce), Riparian shrubland (Prickly Rose, Balsam Willow, Speckled Alder)

Head pond 6.3 Overstorey Trees (Spruce, Poplar, Paper Birch), Shrubs (Speckled Alder, Prickly Rose), Herbs (Blue Bead Lily, Wild Strawberry, Wild Sarsaparilla, Naked Mitrewort, Rose Twisted-Stalk, Fragrant Bedstraw)

Powerhouse and switchyard

0.2 Overstorey Trees (Poplar, Spruce), Shrubs (Speckled Alder, Red Osier Dogwood), Herbs (Woodland Strawberry)

Transmission line 0.5 Mixedwood Forest (Poplar, Spruce) Total 9.1

All merchantable timber to be cleared is to be provided to Domtar Pulp and Paper Products Inc., the sustainable forest licence holder (see Section 4.2.4.1 for more details). Non-merchantable timber is to be cut and stockpiled in an accessible location for local use as firewood. Stockpile locations are to be located at least 30 m away from the watercourse in a location that will not damage present groundcover. Slash and non-salvageable timber is to be chipped and used around the site; materials that are unsuitable for chipping are to be stockpiled in a suitable location away from the watercourse (>30 m) and burned when appropriate weather conditions exist (i.e., low winds) (see Section 5.3.3). Any burning of slash would be conducted in accordance with the MNR burn permit.

Subject to agreement with MNR, reservoir clearing will involve:

• all trees and shrubs greater than 0.05 m diameter will be cleared and removed from the area to the upper limit of the head pond normal operating level (368.8 m elevation),

• no grubbing will take place in this area; stumps will be left no less than 0.15 m above grade, and

• the majority of clearing will occur in shrub and forest edge communities located directly along the river, though forest communities in low-lying areas will also require vegetation clearing.

Impacts to vegetation could also occur due to accidental spills of hazardous materials. Mitigation measures discussed in Section 5.3.3 will also reduce potential impacts on vegetation.


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Increased traffic along South Bay Road may increase the spread of non-native species along the roadside. However, given the existing levels of traffic along the roadway and the temporary nature of construction activities, the effect on spread of non-natives is expected to be negligible.

The generation of dust from movement of vehicles along unpaved roads, excavations, earth-moving activities or other construction activities my result in reduced growth or senescence in plants where significant levels of dust accumulate on photosynthetic surfaces (Hirano et al, 1995, Sharifi et al, 1997). Mitigation measures identified in Section 5.3.3 for mitigating effects of dust on air quality will be effective at minimizing potential effects of dust on plants.

Following construction, rehabilitation of disturbed sites is to be conducted using native vegetation species suitable for this area of northern Ontario. The introduction/use of invasive non-native vegetation species (e.g., birdsfoot trefoil, creeping red fescue) for restoration of disturbed areas will be avoided. In order to confirm success of rehabilitation, an operational monitoring program is proposed in Section 9.3.

5.3.9.2 Wetland Vegetation Impacts to wetlands within the study area during construction will be restricted to potential losses associated with creation of the reservoir. Filling of the reservoir will result in inundation of the small wetland located immediately upstream of the falls. Wetlands in this community will be inundated by 2 to 3 m of water, resulting in the loss of this wetland.

Based on the size of this wetland, it represents a minor loss of the wetland habitat available in the local area. Colonization of the newly created shallows and shorelines within the reservoir will eventually occur as a result of seeding from tributaries, the large wetland immediately upstream of the reservoir, and aeolian and animal transport from downstream of Big Falls. It is anticipated that the low lying area on the west shore approximately 330 m upstream of the weir location will develop into wetland habitat as the head pond matures. Nature colonization of this area with wetland species is estimated to occur within 5 to 10 years.

Loss of this wetland vegetation will represent a minor, negative effect on habitat availability on the Trout Lake River until new wetland habitat develops.

5.3.9.3 Wildlife Impacts to wildlife during the project implementation phase could result from habitat destruction/ alteration due to vegetation clearing, facility development or reservoir creation, direct contact and physical disturbance due to noise (e.g., blasting, heavy equipment use, general construction activities) and human presence.

Access Roads, Transmission Lines and New Facilities Loss of approximately 8.6 ha of wildlife habitat associated with clearing activities for construction of new roads, site structures and associated features, head pond, and the transmission lines is not expected to result in significant impacts to local populations as this area represents an insignificant proportion of habitat in the regional landscape context. No significant wildlife habitats (i.e., for migratory or resident birds, mammals or herpetofauna) have been identified in the potentially affected project area. Mitigation measures previously


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identified with respect to loss of terrestrial vegetation (see Section 5.3.9.1) will be effective at minimizing potential losses of wildlife habitat as a result of clearing activities.

It is possible that some forest fragmentation/edge effects could occur from the creation of new linear corridors for access roads/transmission lines, intake channel/penstock, and construction of site facilities. However, given the existing fragmentation of habitat in this area (i.e., from South Bay Road, the existing 115-kV transmission line, forestry activities, and the scenic trail which is present at the site), the potential implications of these effects are expected to have a negligible effect on local wildlife populations, including Partners in Flight (PIF) priority species, beyond existing levels.

Wildlife species, especially breeding birds, may be disturbed as a result of clearing and blasting activities. In order to mitigate this effect, clearing, blasting, and filling will be scheduled to occur outside the spring and early summer months to minimize the disturbance to wildlife during the peak wildlife nesting and rearing season. With respect to breeding birds, the time period where these works are to be restricted have been established by EC, and are defined by habitat as:

• Forest: May 24 – July 31,

• Open: May 24 – July 23, and

• Wetland: May 16 – July 23.

If clearing or blasting is required during the bird breeding period, an avian biologist will inspect the proposed work area, plus an additional 100 m around the area, for nesting birds (as bird nests and eggs, and migratory birds are considered to be VECs) prior to any site clearing to delineate workable areas (i.e., avoiding nests or other sensitive breeding habitat until area is abandoned for wildlife breeding). If an active nest of a species covered under the federal Migratory Birds Convention Act (MBCA) or the provincial Fish and Wildlife Conservation Act (FWCA) is located within a proposed work area, a mitigation plan (which may include the establishment of buffers around the active nests) will be developed to prevent impacts on migratory birds or their active nests, and submitted to EC (for MBCA species) or MNR (for FWCA species) for review prior to implementation. As a result of this mitigation, minimal impacts on migratory and non-migratory birds and their (nests)/eggs, including PIF priority species, are expected.

The presence of the workforce and construction activities will result in some disturbance to wildlife, in particular species that are sensitive to human presence, including noise. This may result in a temporary retreat from the area during construction. To minimize potential disturbances to wildlife, several mitigation measures are to be implemented:

• all work and the workforce is to be confined to the identified areas,

• equipment is to be removed from site when no longer needed,

• workforce is to stay away from shrubs and tree cover where possible, and

• construction vehicles will be confined to work areas and approved roads.


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Species that retreat from the construction area would be expected to return to the area following removal of the sources of disturbance at the end of the construction period. As construction should occur across a single breeding season, this will not have a significant effect on wildlife populations.

In addition, the presence of heavy machinery on site may result in incidental mortality in species of wildlife as a result of collisions with equipment/vehicles. Mitigation measures intended to minimize disturbance will reduce the risk of collisions during construction activities. In addition, recommended speed limits along South Bay Road are to be followed by the construction workforce, with a speed limit of 30 km/h to be instituted along all roads constructed for the project. Though this is expected to reduce the potential for wildlife fatalities as a result of incidental collisions, it is expected that low levels of fatalities will occur. This is not expected to impact local/regional abundances of wildlife species.

Avian fatalities may also occur as a result of collision with transmission lines. Transmission conductors and structures will be spaced to reduce potential collisions. ‘H’ pole designs will be used to ensure that power lines are on the same level and heights of conductors will be maintained not far above the forest canopy to reduce the potential for collisions or phase to phase connection by birds. Bird flappers or diverters will be placed on lines to reduce the potential risk of collision. Given the relatively small amount of transmission line required for this project, ~200 m, the use of these mitigation measures should reduce potential effects on avian populations to negligible levels.

Reservoir Creation The loss of the small wetland immediately upstream of Big Falls will result in a minor reduction in the availability of this habitat, which also provides moose aquatic feeding habitat, within the study area. However, as discussed with respect to wetland vegetation, this will result in a minor loss of this habitat type within the project area and some eventual recovery along the newly created shallows and shorelines within the reservoirs is expected.

The loss of the wetland will result in some loss of habitat for wetland species, such as amphibians and ducks, as well as moose aquatic feeding areas. Compared to what is available within the regional area, particularly in the vicinity of the pond upstream of the reservoir, there should be no significant reduction in wildlife populations as a result of this loss.

Several beaver lodges were also observed along the river throughout the proposed reservoir. Horizon will work with the local First Nations and/or the local trapper to remove the beavers from this section of river prior to head-pond filling where possible. The increase in head pond surface area, the creation of relatively stable water levels and reduced flow velocities will result in the creation of more favourable habitat conditions for beaver once the head pond is in place. Similarly, waterfowl use of this portion of the river may increase following reservoir filling.

In order to avoid interference with bird nesting that may be occurring within the reservoir area, reservoir clearing will be conducted outside of the breeding season (May 16 through July 31


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annually) if possible. If this is not possible from a scheduling perspective, nest studies will be completed by a qualified biologist prior to clearing an area.

As the hydroelectric plant will be operated as a run-of-river facility, with minor variation in reservoir water levels, there will be no adverse effects on wildlife due to water level fluctuation.

General Construction Activities Impacts on wildlife populations could also result due to spills of toxic or hazardous materials (e.g., fuels, lubricants, paint etc) into soils or watercourses. Mitigation measures discussed in Section 5.3.2.5 will apply to minimize the potential for this effect.

Generation of garbage, particularly food wastes, could result in the attraction of bears to the work area. In order to avoid nuisance bear problems, measures will be taken throughout the construction period to ensure that food wastes are properly contained (i.e., disposal of food wastes in sealed containers, general site cleanliness, etc).

5.3.10 Species at Risk

5.3.10.1 Mammals As discussed in Section 4.1.11, neither woodland caribou nor wolverine are expected to occur in the vicinity of the project with any regularity given existing land use practices.

The project area is located within the Trout Lake Forest, an area that has been subject to extensive harvest operations for a considerable period of time. Given the heavy disturbance within the study area from the harvest of forest resources, it is unlikely that woodland caribou or wolverine occur with any regularity in the vicinity of the project. Big Falls and the adjacent areas are subject to a low level of human use (occasional canoeists on river, fishermen and/or visitors to falls, bait fish harvesting, vehicle traffic along South Bay Road) which would discourage caribou/wolverine from using this habitat. Investigations of Big Falls island found no evidence of present or historical use by caribou. The site habitat is not considered critical to the long-term success of either species within Ontario.

The construction process presents an additional level of disturbance should caribou/wolverine be present or pass through the area (considered highly unlikely). This effect is considered insignificant given the small project footprint (9.1 ha total area).

5.3.10.2 Reptiles and Amphibians No reptile specific inventory work has been completed for reptiles and amphibian, although ancilliary observations were taken while staff were on site for other field activities. No turtle nesting sites were identified during other site investigation. As such, it is determined that Project construction would have limited potential to impact critical habitats for Snapping Turtle, if present within the river system. Some minor loss of potential habitat would be expected to occur as a result of the dewatering of river behind the cofferdam to permit construction, however, areas in close proximity to the waterfalls are expected to be of low use by turtles given the flows and hazards associated with flow over the falls. Workers will be advised of the potential for Snapping Turtles in the work area. Should any Snapping Turtles be observed, the Snapping Turtles will be permitted to leave the work area of their own


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accord. If the turtle has not moved within 24 hours, the MNR will be contacted for further advice. In all instances, the MNR will be notified within 48 hours of the observation.

5.3.10.3 Avifauna Potential impacts from construction activities on avifaunal species at risk are discussed below.

• Bald Eagle – Land clearing associated with the project will reduce potential nesting habitat for Bald Eagles as suitable nest support trees in this portion of the province (trembling aspen) will be cleared. No Bald Eagle nests are known to be present within this area at this time and should any be discovered during construction activities, appropriate mitigation measures will be developed with the MNR to ensure protection of this feature. Suitable support trees will remain present in the local area following construction. As Bald Eagles generally hunt around water (Buehler, 2000), land clearing will not eliminate the Project area from use within a larger territory. Some avoidance of the construction area may occur as a result of human disturbances, however as no bald eagles are known to nest in the area this would result in only a minor reduction in available foraging habitat. Construction activities should therefore not affect the local status of this species.

• Whip-poor-will – Whip-poor-will habitat was determined to only be present within the forests west of the river. Given the large area available west of the river, there will be minimal (<5ha) tree removal from the identified extent of the suitable habitat. As a result, the Project is anticipated to have a negligible impact on Whip-poor-will habitat, however it will be confirmed with the MNR whether a permit is required under the Endangered Species Act, 2007. Project construction may result in some disturbance of Whip-poor-will. Should they be found in the local area, there is abundant retreat habitat available such that no impact on relative Whip-poor-will abundance in the regional area is anticipated.

• Common Nighthawk – Though Common Nighthawk habitat is available within the local area, this habitat is primarily restricted to forest clearcuts, which will not be affected by project construction. Therefore, there will no loss of suitable breeding habitat for this species as a result of project construction. Nighthawk are commonly observed foraging over all types of man-made and natural vegetation communities and are quite tolerant of human activity (Poulin et al., 1996); as a result this species should not be affected by construction activities in the area.

• Olive-sided Flycatcher – The opening of the forest and creation of edges is expected to favour Olive-sided Flycatchers as they are most commonly detected along forest edges (Altman and Sallabanks, 2000). Riparian habitat that is present along the shoreline, and will be lost for reservoir clearing, is suitable for use by Olive-sided Flycatchers, however, this lost habitat will be immediately replaced by habitat available along the new forest edge. As removal of the riparian vegetation will occur outside of the breeding bird period, there will be no impact on breeding flycatchers. Construction activities within or near suitable habitat may result in the temporary movement of breeding individuals outside of


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the area as a result of auditory and visual disturbance, however these activities will be temporary and individuals would be expected to return to the area following construction.

• Canada Warbler – Vegetation clearing associated with the Project will result in some loss of habitat for Canada Warbler. However, suitable habitat will remain present within the area for Canada Warbler and there will be negligible impacts on their population within the local and regional areas. Some temporary movement outside of the area during construction may occur as a result of auditory and visual disturbance, however these activities will be temporary and these species would be expected to return to the area following construction.

• Rusty blackbird – Given rusty blackbird habitat preferences (wet coniferous and mixedwood forests near wetlands), there should be no impact on this species as a result of construction as preferred breeding habitat will not be affected.

5.4 Effects and Mitigation – Socioeconomic Environment

5.4.1 Employment and Economy The overall budget for this project is approximately $26 million, of which approximately $17 million will be for construction.

5.4.1.1 Employment All construction activities (access road construction, site preparation, overflow weir construction, water conveyance structure construction, powerhouse construction, tailrace construction, switchyard and transmission line construction, head pond filling, waste management and site rehabilitation and cleanup) are anticipated to have an effect on local area employment.

Construction of the project will require employment of both skilled and unskilled labour originating locally and non-locally based on qualification. It is anticipated that many qualified persons will be supplied from northern Ontario towns including Ear Falls and Red Lake.

No mitigation measures are necessary as the effect to the local labour force is determined to be positive.

5.4.1.2 Economic Benefits Local communities with the potential to benefit most from the project are the towns of Ear Falls and Red Lake. These benefits are expected to be direct and indirect in the form of income and employment expenditures, as well as material expenditures.

Based on a report completed by AECOM for the Ontario Ministry of Natural Resources dated April 2012, titled “Economic Impact of Waterpower Projects on Crown Lands in Ontario”, it is estimated that between 3 and 5% of the overall project budget is spent locally. This would result in an estimated $780,000 to $1.3 million will be spent locally in connection with this project. This estimate does not include any revenue sharing with future First Nation ownership partners (i.e., Wabauskang First Nation and Grassy Narrows First Nation).


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Direct economic benefits would include income to the construction workforce and utilization of local and regional suppliers that would provide services, equipment and materials for the project.

Indirect benefits would consist of expenditures in the local community on basic goods and services, e.g., accommodation, fuel, restaurant services and general convenience sales. There will be no on-site construction camp.

5.4.1.3 Local Businesses Local businesses discussed in Section 4.2.1.6 and those business owners/operators farther downstream from the project (i.e., Bruce and Pakwash lake lodge/fishing camp owners) have expressed concerns regarding the potential impacts to various elements of the natural environment as a result of the project. These concerns are related to the potential for adverse effects to the Trout Lake River fish community, which could affect resource-based tourism and recreational operations. Mitigation measures (erosion and sediment control, implementation of blasting plans, etc) will be undertaken during construction to control potential adverse effects to water quality and the fish community.

Negative effects to the social environment may also include delays and increased traffic on South Bay Road; and loss of access to the Big Falls area during construction of the project. Potential negative effects to traffic on local highways and roadways and proposed mitigation measures are discussed in the following section. Loss of access to Big Falls will occur during the construction of the project. The following mitigation measures are proposed to limit the disturbance in the vicinity of the project:

• all staff and site visitors are to remain within predetermined areas,

• vehicles are to be equipped with effective muffler and exhaust systems,

• control of vehicle and equipment speed,

• soil stockpiles to be covered,

• dump trucks transporting soil/excavated material to be covered when warranted,

• temporary storage piles of fine materials to be worked from the downwind side,

• use of water spray dust suppression as necessary,

• vehicles and equipment not left idling, but run only when necessary,

• limited vehicles to existing trails and approved roads where possible.

The residual effect of the project will be some disturbance in the vicinity of the project as a result of construction activities, increased traffic and loss of access to falls within the construction area


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5.4.2 Transportation and Infrastructure

5.4.2.1 Local Highways and Roadways Potential negative effects to the local infrastructure include increased local traffic and temporary disruption along routes used, resulting in delays to the local community traffic, and increased traffic on Highways 105 and 657, in addition to South Bay Road. During construction of the project there may also be activities that require temporary disruption to traffic flow on local highways and roadways including the delivery of large equipment to the site.

To reduce the disruption and alleviate adverse effects, the following mitigation measures are recommended:

• contractor work force and construction activities to be undertaken in compliance with the Highway Traffic Act,

• designate transportation routes to avoid tight turning areas and delays,

• check overhead lines to determine the requirement for temporary removal or relocation (the appropriate utility will be contacted),

• use a police escort or security company to guide/accompany any transport conveys as necessary,

• use flagmen to facilitate traffic flow and control,

• drive construction vehicles in a proper manner and respect all traffic laws, regulations, and company policies, and

• mitigate vehicle imprints and erosion gullies.

The residual effect of project construction on local traffic remains the potential for disruption and delays along routes used.

5.4.2.2 115-kV Hydro One Networks Inc. Transmission Line Power generated by the station will be transmitted to the provincial grid via a new, 115-kV transmission line from the powerhouse switchyard to the existing 115-kV distribution line, owned by HONI, located approximately 200 m east of the powerhouse location along the east side of South Bay Road. Since the ROW will be located adjacent to the permanent site access road, no access along the ROW itself will be required.

The interconnection of the facility has the potential to affect HONI’s existing line. A Connection Impact Assessment and a System Impact Assessment were completed by HONI and IESO in 2010 outlining potential impacts and required upgrades to be completed prior to connection to the provincial grid.

5.4.2.3 Emergency and Medical Services The influx of personnel to the area during the construction of the project may result in an increase in use of emergency and medical services. It is anticipated that local services would


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be equipped to ensure adequate care in an emergency, therefore no effect to emergency or medical services is expected as a result of the project.

5.4.3 Crown Land Policy and Land Use

5.4.3.1 Crown Land Policy Although the construction of the project will result in loss/alteration of alternative Crown land uses (e.g., recreation), the proposed project is to be constructed within the boundaries of the Red Lake General Use Area which permits hydroelectric development. Therefore, the proposed project is acceptable in relation to Crown Land Use policy.

5.4.3.2 Land Use Potential land uses to be affected during construction of the project include resource and industrial uses (Section 5.4.4); hunters, trappers, and anglers (Section 5.4.5); recreational (Section 5.4.6) and tourism (Section 5.4.7). Potential effects to these uses and any proposed mitigation measures are discussed in the sections of this report just noted.

5.4.4 Resource and Industrial Activities

5.4.4.1 Forest Resources According to Domtar’s Trout Lake Forest – 2009-2019 Forest Management Plan: Preferred and Optional Harvest Areas (Domtar Pulp and Paper Products Inc., 2009a) the majority of the project area is designated Optional Harvest Area. Given that there are few Preferred Harvest Areas located within the project area; effects to forestry operations would be limited to potential delays on South Bay Road as it will be utilized by both forestry and project construction traffic. Mitigation measures to reduce potential negative effects to traffic are discussed in Section 5.4.2.1

Clearing of forestry resources during the construction of the project will result in harvesting of merchantable timber during clearing for access roads, construction laydown areas, transmission line corridor, etc. The following mitigation measures are proposed:

• A merchantable timber survey will be performed to determine the amount of merchantable timber to be harvested within the cleared forested area.

• An Overlapping Forest Licence Agreement will be negotiated between Domtar and Horizon Hydro

• All merchantable timber will become the property of the Sustainable Forest License holder (Domtar Pulp and Paper Products Inc.).

• Wood that cannot be sold will be chipped and used as mulch during project restoration activities.

• The contractor may opt to burn the slash. Burning will be completed in accordance with an MNR Burn Permit.

The residual effect of project construction will include a potential increase in traffic on South Bay Road when logging operations are active; and harvesting of forestry resources during clearing operations.


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5.4.4.2 Mineral Resources Numerous mine claims are staked along South Bay Road, and one covers the project area (#1210025). The holder of a claim (Aurcrest Gold Inc.) possess the rights to the mineral resources as well as the first right of refusal to the surface rights required to access the surface area and conduct prospecting and mineral exploration. Horizon Hydro has obtained a ‘Consent to the Disposition of Surface Rights” from Aurcrest for the project area.

5.4.5 Hunting, Trapping and Fishing

5.4.5.1 Hunting (General) Construction traffic and road upgrading occurring during any portion of the hunting season may impact hunter success in WMU #3 due to access impediment and altered animal movements in the area. This effect will be limited to the areas in the vicinity of construction activities. This effect is determined to be negligible given available alternate access to and abundance of area habitat. No mitigation is necessary.

5.4.5.2 Hunting (Bear Management Areas) Construction of the facility will create noise and a human presence in the area that may reduce the value of the area for hunting. Head-pond filling will also result in the flooding of 6.3 ha of riverbank within BMA RL-03-028. As a result, the holder of BMA RL-03-028 will experience a small reduction in this area, which is not expected to adversely affect hunting opportunities, given the large surrounding area. To mitigate this effect the following measures are proposed:

• The holder has been contacted by Horizon Hydro or the Contractor and notified of the proposed construction activities that will occur during the bear hunting season (August 15 to October 31).

The residual effect of construction activities on BMAs is a potential loss of hunting opportunity due to loss of habitat and construction disturbance but is not expected to be significant. Horizon sent a letter to the BMA holder on January 2, 2013 to provide additional information on the proposed Project, request information from the BMA holder (i.e., location of bear baiting stations in the area, potential impacts on baiting stations during the 12 to 18 month construction period, potential impact during operations, and total annual income from BMA operations in the area). Horizon indicated a commitment to compensate the BMA holder for any losses that are deemed to be caused by the Project. The BMA holder responded on February 6, 2013 with some potential impacts during construction. Horizon has since requested further information prior to finalizing an agreement to mitigate/compensate any losses experienced by the BMA holder due to the Project.

5.4.5.3 Trapping The project area is within licensed trapping area RL-17. Construction activities have a potential to affect harvest success within trapping area RL-17 based on construction timing and location of the trapline. Therefore, the following mitigation measures are proposed:


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• The holder of trapline RL-17 has been contacted by Horizon Hydro and notified of the location and timing of construction activities.

The residual effect of construction activities on trapping resources is a possible loss of trapping opportunity but is not expected to be significant. Horizon sent a letter to the registered trapper in the area on January 2, 2013 to provide additional information on the proposed Project, request information from the trapper (i.e., location of traplines, types of animals trapped, potential impacts on trapping operations during the 12 to 18 month construction period, potential impact during operations, and total annual income from trapping in the area). Horizon indicated a commitment to compensate the trapper for any losses to trapping revenue deemed to be caused by the Project. At the time of writing, no response had been received from the Trapper. Horizon will continue to follow-up with the trapper regarding this issue.

5.4.5.4 Fishing There are several boat caches located both upstream and downstream of Big Falls, and various species of game fish exist in this area (i.e., walleye, northern pike). Although angling is noted to occur both upstream and downstream of the proposed project, any changes in access to the area by way of water are considered to be negligible given Big Falls is a pre-existing navigation impediment with an associated portage. Public access to the construction area will be restricted throughout the construction period (for public safety), although the area below the falls will be largely unaffected (except for the southeast shore) and will be available to anglers.

During public consultation, concern was expressed regarding baitfish harvest areas. As stated above, access to the area above and below Big Falls will be available to the public, and the harvest of bait fish can continue. If an alternative public access route to the upper or lower river is required during construction, it will be provided by the proponent. Access to areas outside the construction zone will be provided by means of a written request to Horizon for access to specific area, and a subsequent review (by Horizon or contractor) to ensure that area requested is not within work zone and/or could endanger a member of the public.

Horizon sent a letter to the licensed bait fish harvester in the area on January 2, 2013 to provide additional information on the proposed Project, request information from the harvester (i.e., location of harvesting and potential impacts on bait harvesting operations during the 12 to 18 month construction period, potential impact during operations, and total annual income from trapping in the area). Horizon indicated a commitment to compensate the bait fish harvester for any losses to bait fish harvesting revenue deemed to be caused by the Project. At the time of writing, no response had been received from the bait fish harvester. Horizon will continue to follow-up with the harvester regarding this issue.

5.4.6 Recreational Uses

5.4.6.1 Canoeing/Kayaking As noted in Section 4.2.5, there are two portage routes around Big Falls, one on the east side and one on the west side. The west side route will be unaffected by project construction and will be open for use during that entire period (see Figure 4.32). The east side route includes


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a series of short portages around the rapids in the upper 700 to 1700 m above the falls, and a longer (350 m) portage around Big Falls on the east bank using mostly the existing trail from the WSC gauge to South Bay Road. The portage trail branches off near the bend which turns toward South Bay Road, and descends down the bank to the eastern limit of the embayment below the falls. This latter portion (i.e., 350 m long section) is within the construction work area and will not be available during the construction process. Horizon Hydro will provide and maintain a safe alternative to bypass both Big Falls and the construction area.

The following measures are proposed to alert recreational users regarding construction activities and to mitigate impacts on features used:

• Place warning signs at the upstream approach to the portage trail to alert canoeists of construction activities including potential dangers at the site and directions for safe passage around the area.

• Relocate/upgrade any existing portages (i.e., west side route) to allow safe passage of canoeists during construction.

• Fence the construction work areas to ensure public safety.

Given the presence of South Bay Road within 150 to 200 m of Big Falls, the site is not considered remote and would be subject to traffic noise (i.e., log trucks and other vehicle traffic). Construction at the site will add to noise levels and further diminish any feelings of remoteness or “wilderness” environment. This effect is not mitigable during the construction period.

5.4.7 Tourism As discussed above, a number of tourism outposts, camps and lodges exist upstream and downstream of the study area. Mitigation measures have been proposed to control potential adverse impacts to the aquatic and terrestrial environments, so that downstream tourism resources are not affected.

Big Falls is considered to be a scenic attraction, although use of the area is considered to be minimal. Flows will be unaffected during the construction process, and access to view the falls will be possible, although some areas (active work/excavation areas) will be ‘off limits’ to protect public safety.

5.4.8 Lands and Resources Used for Traditional Purposes by Aboriginal Persons Information regarding the traditional use of lands and resources by Aboriginal persons has been collected during Aboriginal Information Sessions and various meetings with the members of the Lac Seul, Grassy Narrows and Wabauskang First Nations as well as the Métis Nation of Ontario. It is currently understood and stated that the proposed development would be within the traditional use areas of these communities.

One small wild rice bed (<100 m2) is present within the proposed head pond for the facility. It is not known who, or if anyone, is currently harvesting this rice. Horizon will develop plans for the replacement of this area during the final design stage. Aboriginal communities will be contacted to obtain seed to re-establish a new wild rice bed within the head-pond area and


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consideration will be given to contract growing local seed such that plugs can be replanted to assist in re-establishment. The re-established wild rice area will be monitored following planting to ensure it is successfully re-established (see Section 9.3). No further mitigation is therefore necessary.

No information on Aboriginal harvesting of medicinal plants from the project area has been provided by any Aboriginal community. However, during aboriginal consultations, some community members pointed out that some medicinal plant species (i.e., tamarack and water lily) were present in photographs of the area. Should potential loss of these medicinal plants due to facility development be of concern to Aboriginal communities, Horizon is committed to ensuring that mitigation is implemented. Horizon would walk the project footprint with a known expert in medicinal plants from a local Aboriginal community and commit to developing a plan to address any negative impacts on medicinal plant use prior to construction.

The employment of a local workforce during construction activities is a positive effect on the La Seul, Grassy Narrows and Wabauskang First Nations as well as the Métis Nation of Ontario. Horizon Hydro will employ members of these communities wherever possible.

5.4.9 Archaeological and Heritage Resources A Stage One and Two Archaeological and Heritage Impact Assessment was completed of the project area. A potential archaeological site was identified on Big Falls island during the Stage 1 assessment, but the site could not be found during the Stage 2 Assessment despite a detailed search of the island. No artifacts or human modifications to the landscape were found on the island or site area during the Stage 2 Assessment. The report concluded that the site of the proposed development is considered to have a low archaeological potential and the MTCS issued a letter confirming their agreement with this conclusion.

The MTCS has specified mitigation that must be undertaken in the event of discovery of human remains or other archaeologically or culturally significant material.

• Should human remains be identified during the construction, operations or decommissioning of the project, all work in the vicinity of the discovery will be halted immediately, as required by the Ontario MTCS regulations under the Ontario Heritage Act.

• Notification will be made to the Ontario Provincial Police, or local police, who will conduct a site investigation and contact the district coroner.

• Notification will also be made to the Development Plans Review Office, Ontario Ministry of Culture, Heritage and Libraries Branch, Heritage Operations Unit, 400 University Ave, 4th Floor, Toronto, ON, M7A 2R9, and the Registrar of Cemeteries, Ontario Ministry of Consumer and Commercial Relations.

• Work would be halted if any artifacts are found until the site can be investigated and cleared by a licensed archaeologist.

Careful adherence to the above mitigation measures will avoid negative residual effects on cultural and heritage resources.


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If requested by First Nations communities, Horizon will work with them to develop a suitable protocol to inform First Nations if any archaeological resources are uncovered during construction.

5.4.10 Health and Safety

5.4.10.1 Construction Site Safety The following mitigation measures are recommended to ensure the safety of all workers on the construction site:

• completion of safety training program by all workers,

• strict adherence to the Ministry of Labour occupational health and safety regulations pertaining to construction sites regarding worker safety,

• first-aid equipment, as appropriate to the activity to be maintained on site,

• Material Safety Data Sheets for any hazardous material used on site to be available close to the location where the material is used and stored,

• an accident and emergency spill response plan,

• spill containment and clean-up materials on site,

• training to deal with spill situations.

The residual effect of project construction will be a minimized risk to construction site safety.

5.4.10.2 Public Safety in the Vicinity of the Project Public use in the vicinity of the project (including that by trappers, hunters, campers, canoeists/ kayakers) during construction may result in public safety concerns.

The following mitigation measures are recommended to enhance public safety in the vicinity of construction activities:

• prevent public access to the construction site through use of gate(s), and security procedures,

• post signage to notify the public of construction in the area, and alternate routing around the site,

• use flagmen as required to ensure that traffic on access roads is controlled,

• drive construction vehicles in a proper manner and respect all traffic laws, regulations, and company policies.

The residual effect of project construction will be a minimized risk to public safety.

5.4.11 Waste Management Solid wastes generated during construction will include domestic waste such as food and sanitary waste and construction waste such as material packaging and scrap material. Sanitary facilities on site will include several portable self-contained toilets and washroom facilities in a crew trailer. All solid and sewage wastes are to be contained and hauled off site


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by a designated hauler throughout the construction period. All domestic and construction waste will be transported to an MOE licensed landfill by an MOE licensed hauler.

The following mitigation measures are to be implemented to ensure the protection of on-site personnel, the public and the environment:

• store hazardous wastes in double walled containment tanks or impervious berms until disposal off site at a registered facility,

• store solid wastes on site prior to disposal off site at local registered disposal facilities,

• practice reuse and recycling whenever possible, and

• securely contain domestic waste to avoid a nuisance bear situation prior to disposal off site (approximately twice weekly during summer months).

The residual effect of project construction will be the proper disposal and recycling of waste materials as appropriate.

5.5 Accidents and Malfunctions The following section provides an assessment of potential accidents and malfunctions during construction. These can include dam and cofferdam failure, flooding of the work area, spills and accidental fires. The assessment also includes a discussion on the probability and extent of the incident.

5.5.1 Dam and Cofferdam Failure During the construction of the overflow weir, failure could potentially occur if it is not constructed according to the design. Since the overflow weir will be constructed in the dry behind cofferdams, the likelihood of failure is significantly reduced since exposure to water would be the most probable cause of failure. Routine inspection during construction on the dam integrity and any related problems or indicators would reduce the potential for failure.

Cofferdams will be one of the primary structures that will retain water during the construction period. Although they are for temporary use, they will be designed by professional engineers to the full standards and requirements of current MNR Dam Safety Guidelines under the Lakes and Rivers Improvement Act. Accordingly, it will be expected to have the same low probability of failure as the adjacent water retaining structures and is a managed, low grade risk.

A job safety plan will be prepared and distributed to the labour force on site, instructing them on how to safely work around water, including what to do in the event of a dam or cofferdam failure.

5.5.2 Flooding of Work Area There is a risk of seepage through, over or beneath temporary construction cofferdams which could cause delays to construction. This can be the result of quality of construction, hydrologic events or foundation conditions. This will impose a commercial risk to the construction contractor based on potential additional costs for handling/pumping water. There are also schedule implications if the cofferdam water barrier is ineffective. In addition,


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accidental flooding of the work area could result in ponding of turbid or polluted water within the cofferdam area. This would have to be pumped out and adequately treated to meet discharge requirements prior to release back to the river. To mitigate the potential construction delays, scheduling and cost concerns and potential environmental effects, inspection on cofferdam integrity will be completed during construction.

The cofferdams will likely be designed for a 1:20-yr flood. However, a hydrologic event of greater magnitude resulting in increasing water levels to the point of overtopping a cofferdam could occur. Such an event would be forecast well in advance, thereby allowing pre-removal of equipment and evacuation of all workers. This will minimize the potential effects of cofferdam overtopping on worker and equipment safety, although the work under construction could potentially be impacted. Environmentally, flooding of the work area, particularly during a big flood event, could potentially result in an increase in turbidity in the downstream area. Considering that the majority of the tailrace and overflow weir cofferdam works areas are predominantly exposed bedrock, and that excavation will occur within bedrock, it is anticipated that the amount of fine sediments accumulating at the base of the dewatered work area would be minimized. Therefore, any increase in turbidity would be anticipated to be minor in magnitude and temporary in duration.

A job safety plan will be prepared and distributed to the labour force on site, instructing them on how to safely work around water, including what to do in the event of a flood.

5.5.3 Spills

5.5.3.1 Discharge of Sediment to Aquatic Environment During the construction phase, numerous erosion and sedimentation control measures will be installed to prevent siltation to aquatic and terrestrial environments based on the Erosion and Sedimentation Control Plan that will be prepared prior to construction. The discharge of sediment into aquatic environments could have the potential for negative effects to aquatic biota and habitat due to turbidity or deposition of debris and material. Reversibility of environmental effects will depend on the species life stage present (fish, benthic organisms and amphibians) and the proportion of a water/wetland feature affected. Depending on the amount of sediment and flows within the area of the discharge, the impact could be extensive and wide ranging, or minimal and localized.

Sedimentation could occur during the following construction activities: site stripping, clearing, grading and excavation activities; access roads construction, staging, stockpiling and material storage; erection of buildings, facilities and installation of equipment; fill placement activities; dewatering activities; work in and around water; in-water blasting; and, spill prevention activities. Failure of shoreline vegetation restoration could also result in a discharge of sediments to the aquatic environment since shoreline soils would become exposed and erode.

In order to minimize or prevent the release of sediment, the following mitigation measures are proposed:


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• Stockpiles of erodible materials (e.g., soil and overburden) will be located away from any water feature and if necessary, environmental protection measures (e.g., silt fence barriers) will be installed between the stockpiles and the water feature.

• Site stripping, clearing, grading, fill placement and excavation activities will not be taking place within 30 m of a water body unless otherwise required. If required, work methods and erosion and sedimentation control measures will be installed to prevent sediments entering the water body.

• Erosion and sedimentation control measures will be installed, as required, during access road construction, spill prevention activities, blasting operations and cofferdam removal.

• During dewatering activities, the discharge of water will be in accordance with the Environmental Compliance Approval and/or PTTW, if applicable, and erosion and sedimentation control measures will be installed to minimize any sedimentation in a water body.

• In-water blasting will be conducted in accordance with the DFO’s Guidelines for the Use of Explosives In or Near Canadian Fisheries Waters and the Contractor’s Blasting Plan.

• During restoration activities, appropriate erosion and sedimentation controls will be used and restored shoreline vegetation will be monitored on a yearly basis for the first 3 years.

The Contractor is required to provide an Erosion and Sedimentation Control Plan which will outline specifically the measures that will be installed to prevent erosion and sedimentation, and protect aquatic resources during all different types of construction activities that could result in erosion and sedimentation. The environmental protection measures will be installed in accordance with Ontario Provincial Standard Specifications 577.

For the most part, these effects and frequency of occurrence are considered to have a low to medium potential. The effects could vary depending on the severity of the sediment release but would tend to be local in extent, minor in magnitude, short-term in duration and generally mitigable through the implementation of measures described above. The risk is considered minor.

During construction, all erosion and sedimentation control measures will be inspected and modified, if necessary, to ensure maximum environmental protection.

5.5.3.2 Release of Petroleum Hydrocarbons and/or Other Hazardous Substances There are numerous activities during construction that involve the use or transfer of petroleum hydrocarbons and other hazardous substances. Petroleum hydrocarbons include, for example, diesel fuel, light or medium oils, hydraulic fluid and lubricants. Other hazardous substances include, for example, pressurized gases, and chemicals used in the production of concrete (such as air entrainment additive, super plasticizer and set retarder).

Activities where a release of petroleum hydrocarbons and other hazardous substances may occur include:


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• transfer of fuels from an above ground storage tank to a vehicle,

• use of fuels and other petroleum hydrocarbons by all vehicles,

• transfer of petroleum hydrocarbons during the maintenance of vehicles,

• storage of fuels, pressurized gases (e.g., oxygen, acetylene, propane and compressed air) and chemical additives, and

• transportation and use of chemicals used in the production of concrete.

Accident scenarios include the release of these substances during the above listed activities to either surface water or land; thereby potentially impacting soils, vegetation, aquatic life, wildlife and groundwater. A release to the land could then impact groundwater during percolation. An accident involving pressurized gases or fuel spills allowed to volatilize would cause a release of the gases to the atmosphere.

The potential effects to the terrestrial environment would likely be localized, short term and reversible contamination of surface vegetation and soils, dependent on the size of the spill. The potential effects to the aquatic environment may not be localized, short term or reversible depending on the size of the spill, response time and methods for containment and cleanup.

To prevent and minimize the potential occurrence of a release of petroleum hydrocarbons or other hazardous substances during construction to surface water or land the following measures have/will be implemented:

• no construction activities will take place within 30 m of a water feature unless otherwise required,

• no refueling, or maintenance of vehicles will take place with 30 m of a water feature,

• all mobile equipment will be inspected for leaks on a regular basis and maintained in good working order,

• refueling will take place in designated areas, and

• storage of petroleum hydrocarbons and other hazardous materials will be in accordance with applicable legislation and with secondary containment.

Implementation of these measures would result in a low risk of a release to both the terrestrial and aquatic environments.

For the most part, the probability of an event occurring during construction is moderately high given the activities on the site; however, generally, the effects are considered to have a low potential and would be local in extent, minor in magnitude, short term in duration and generally mitigable through the implementation of measures described above. The risk is considered minor.

5.5.3.3 Release of Liquid Concrete Concrete will be brought on site by a ready-mix supplier throughout the duration of construction. Concrete will be poured for the overflow weir, intake and powerhouse under


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dewatered conditions, within cofferdams where necessary. Concrete could be released during transport to these locations and from the form work within the cofferdams at each location. If accidentally releases were to occur, impacts would occur to the aquatic environment as uncured liquid concrete is toxic to fish due to its alkaline nature. No in-water concreting is anticipated to be required.

In order to prevent the release of liquid concrete, the cofferdam would be constructed such that the likelihood of leaks to the aquatic environment is minimized and chutes or concrete pump delivery lines would have joints and connections sealed and locked. Crews would ensure that concrete forms would not be overfilled, thereby preventing a release.

For the most part, these effects and frequency of occurrence are considered to have a very low potential. The effects would be local in extent, minor in magnitude, short term in duration and generally mitigable through the implementation of measures described above. The risk is considered minor.

5.5.3.4 Release of Sewage Construction workers will be utilizing either, or a combination of, portable units or tanks. Both will require the removal of sewage on a regular basis by a MOE approved hauler to a MOE approved facility. Overfill or transfer could result in a release of sewage to the terrestrial or aquatic environments.

To mitigate, the following will occur:

• all tanks and portable units will be located no closer than 50 m from a water body unless a containment system is in place, and

• spill equipment will be available during transfer of sewage.

For the most part, these events are considered to have a low potential and frequency of occurrence would also be low. The effects would be local in extent, minor in magnitude, short term in duration and generally mitigable through the implementation of measures described above. The risk is considered minor.

For all of these potential spill events, the Contractor is required to act and maintain compliance with applicable guidelines, legislation and best management practices to minimize the risk of spills. The Contractor will prepare a Spills Response Plan for all types of spills outlining how the Contractor will prevent, prepare for and respond to spills events. The Contractor will also provide the reporting procedures if a spill does occur.

5.5.4 Accidental Fires Accidental forest fires can be started by anthropogenic and construction activities. There are very few situations where a flame is required during the construction activities. However, there are situations where a flame can be developed, such as sparks on mechanical equipment, discarded cigarettes, arson or mismanagement of recreational campfires. Also, the Contractor may opt to burn slash.


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Forest fires can have adverse effects on wildlife and their habitat and human health, safety and property. Smoke generated by the fire would also have an adverse effect on local air quality.

The Contractor will be required to have on hand appropriate fire suppression equipment and to develop communications, notifications and reporting protocols, initial response procedures. All mechanical equipment shall be equipped with spark arrestors and be kept free of any accumulation of flammable materials.

For the most part, these effects are considered to have a low to high potential. The frequency of occurrence would be low given the requirements to monitor all activities that could result in a fire. The effects tend to be local in extent, minor in magnitude, short term in duration; however, there is the potential for an event that could result in effects that are large in magnitude. The implementation of measures described above, would greatly reduce the risk; therefore, the risk is considered minor.

5.6 Summary of Impacts and Mitigation During Project Implementation Table 5.3 provides a summary of the potential effects from construction activities, the proposed mitigation and any residual effects after mitigation.


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Table 5.3 Summary of Effects and Mitigation During Construction

Environmental Component Sources of Effect Potential Effects Mitigation Net Effects Bedrock - Blasting and excavation of bedrock at

powerhouse, overflow weir, intake and tailrace locations.

- Adverse effects on local geological stability or significant landforms.

- Blasting conducted in a controlled manner by a licensed blasting contractor to avoid adverse effects on stability

- Bedrock landforms not uncommon in local area.

- No residual effect.

Soils

- General construction activities resulting in soil exposure.

- Soil erosion and loss of soil resources. - Implementation of sediment and erosion control plan to prevent/minimize soil loss. - No residual effect with effective mitigation.

- Use of hazardous materials on site (e.g., fuels, lubricants).

- Soil contamination resulting from spills of pollutants.

- Spill prevention and contingency plan to be developed by contractor prior to commencement of work. Handling of hazardous materials conducted at designated sites. Chemical handling procedures to be developed by the contractor, and adequate spill containment materials onsite. Employees trained in proper handling and emergency spills response. Any spills cleaned up immediately. If required, contaminated soils to be remediated or removed from the site to an approved disposal area. Soil contamination to be visually monitored following construction. On-site equipment to be inspected to ensure well-maintained.

- No residual effect with effective mitigation.

- Heavy equipment use and stockpiling of construction materials.

- Soil compaction resulting in impacts to plant growth and water infiltration.

- Equipment to remain within predetermined work areas. If required, compacted areas to be remediated through deep tilling or other soil loosening methods.


- Work along edge of river.

- Bank instability or slumping associated with shoreline work or vegetation clearing.

- Heavy machinery to be restricted to predetermined areas and bank stability monitored during construction. Disturbed riverbanks to be stabilized with native plant material or other bioengineering/ structural methods.


- Soil stockpiling. - Impaired soil health due to effects of stockpiling. - Separate topsoil and subsoil prior to stockpiling.

- Minimizing duration of stockpiling by construction phasing. - Minimizing depth of stockpiles to >1 m where feasible.


Air Quality and Noise - Traffic along access road, soil moving and stockpiling, erosion from disturbed areas and other construction activities (e.g., crusher use, blasting).

- Increased dust levels along road and in work areas. - Contractors to follow Best Practices for the Reduction of Air Emissions from Construction and Demolition Activities” (Cheminfo Services Inc., 2005). Water roads or use approved chemical control. Cover or stabilize stockpiles to avoid erosion. Utilize phased construction to limit duration of soil exposure. Control dust during blasting through the use of blast mats or other similar techniques. Use appropriate mitigation to minimize dust generation during crusher use, and utilize dust curtains on loaded dump trucks traveling off site.


- Use of combustion equipment. - Noise emissions due to heavy equipment

use and blasting during construction

- Increased emissions of combustion productions from vehicles and machinery will result in short-term increase in local airborne contaminant concentrations.

- Increased noise in local area around construction site.

No negative effects on noise levels at closest sensitive receptor (1.2 km from construction area) anticipated to occur.

- Maintain vehicles and emission systems. Use vehicles only when necessary. Reduce unnecessary idling.

- Construction equipment noise emissions will adhere to MOE NPC guidelines. Standard

equipment noise muffling devices will be used.


Groundwater - Excavation for powerhouse, penstock, intake and tailrace.

- Local reduction in groundwater levels. - Adverse effect on excavation activities due to

groundwater infiltration into works.

- No local use of groundwater, no mitigation required. - Dewatering mechanisms (if required) installed during construction, and operated in

accordance with applicable permits (i.e. water treated prior to discharge if necessary).

- No residual effect. - No residual effect with effective

mitigation.

- Use of hazardous materials on site (e.g., fuels, lubricants, explosives).

- Groundwater contamination through spills, fuel leaks and accidents involving fuels, lubricants, etc.

- Minimal infiltration anticipated due to low hydraulic conductivity. Apply spill prevention and containment procedures, including use of bermed storage and fuelling areas, only clean, well-maintained machinery allowed on-site, adequate spill containment material on site.



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Environmental Component Sources of Effect Potential Effects Mitigation Net Effects Hydrology (flows and water levels)

- Head-pond creation. - Cofferdam construction and short-term

water diversion at intake channel/overflow weir and tailrace area.

- Vegetation clearing, land grading,

ditching, drainage improvements resulting in more impervious surfaces.

- Increase in head pond water levels, water volumes and surface area, reduced flow velocity.

- Changes in local hydraulics, water levels or flow

velocities due to constriction or redirection of river flow during construction.

- Potential increase in local runoff rates and quantity, and

associated decreases in runoff duration.

- Head pond filling will occur during high flow periods or gradually using a low impoundment rate (10% of instantaneous river flow) to avoid significant changes to river hydrology.

- Cofferdams for Stage 1 will be constructed so as not to impede river flow. River flow will be

redirected through control gates during Stage 2 of construction. - Erosion and sediment control plan developed and implemented as required (e.g., check dams,

collection basins if required, maintenance of vegetated buffers, etc) to reduce potential for flashy flows.

- Minor short-term change in river hydrology during head pond filling: no long term residual effect.

- Minor short-term change in

immediate site areas; no long term residual effect.

- No residual effect with effective

mitigation.

Surface Water Quality

- Vegetation clearing, exposure of mineral soils, stockpiling, and other drainage alteration.

- Cofferdam installation/removal, culvert

installation and other in-water activities. - Use/storage of hazardous materials (e.g.,

fuel, lubricants). - Release of construction debris. - Release of sewage effluents. - Potential for Acid Rock Drainage (ARD)

- Impaired surface water quality due to increased turbidity and suspended solids.

- Impairment to surface water quality due to increased

turbidity and suspended solids. - Impaired water quality due to spills or use of machinery in

watercourses. - Impaired surface water quality. - Impaired downstream surface water quality. - Impaired surface water quality due to ARD.

- Implementation of erosion and sediment control plan. Monitor turbidity and/or suspended solids through the construction period. Locate stockpiles away from watercourses and drainage ways. Stabilize/revegetate disturbed areas as soon as possible. Utilize check dams, vegetation cover, buffer strips, stormwater management techniques and other measures to reduce/eliminate sediment transport into watercourses.

- Use clean rock fill for cofferdam construction. Contractor to monitor water quality and take

corrective actions as required. - Proper storage and use of cement and other construction materials. Allow only clean, well

maintained machinery in/near water. Maintain adequate spill containment material onsite. Notify the Ontario Spills Action Centre immediately of any spills.

- Work site isolation, containment, clean-up and good general housekeeping practices

implemented to prevent escape of debris. - None required - self-contained facilities to be used on site with appropriate off-site disposal. - ARD potential expected to be low based on area geology, although no samples tested to date.

Rock samples tested prior to use in sensitive environments (e.g., in vicinity of watercourses or wetlands). Mitigation to be implemented in the unlikely event that bedrock does have acid generating potential (e.g., containment in disposal areas).


- Short-term effect during cofferdam

installation and removal. - No residual effect with effective

mitigation. - No residual effect with effective

mitigation. - No residual effect. - No residual effect anticipated.

Aquatic Biota

- Impaired surface water quality due to fugitive dust deposition and/or erosion and sedimentation.

- Accidental spills or leaks of potentially

hazardous materials (e.g., fuels, oils, cement, explosives).

- Cofferdam installation/removal and

shoreline works.

- Blasting in or near fisheries habitats.

- Dewatering behind cofferdams.

- Head pond filling/creation.

- Potential impacts on fish health due to surface water quality impairment.

- Potential impacts on fish health due to surface water

quality impairment. - Disruption of fish and locally increased turbidity resulting

in injury to aquatic biota, altered foraging and/or behaviour.

- Fish mortality or injury due to blasting. - Stranding of fish behind cofferdams and dewatering of

benthic habitat areas. - Potential impacts to aquatic biota as a result of changes

to aquatic habitat (greater depth, reduced flow velocity).

- Erosion and sediment control plan and construction monitoring to ensure no significant releases of sediment to the watercourse.

- Mitigation measures identified previously are anticipated to be effective in preventing impacts

associated with spills/accidents. - In-stream construction (including blasting) to avoid sensitive fisheries reproductive periods

(September 15 to June 15) and to occur ‘in the dry’ behind cofferdams. - Blasting in accordance with DFO guidelines (Wright and Hopky, 1998). - Contingency plan for fish removal to be prepared by contractor. Dewater with shrouded pump

to water depth of 0.5 m, then remove remaining fish as per permit requirements. - Filling to avoid disruption of spring/fall spawning/incubation activity. Install replacement habitat

works to offset losses of fast water habitat for benthic invertebrates and fish spawning



mitigation. - Minor disruption, but no mortality

anticipated. Short term effect with effective mitigation.


mitigation. - No residual effect on fish after

application of mitigation. Residual effect on benthic populations in dewatered areas.

- Short term residual effect until

replacement habitat becomes fully functional.


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Environmental Component Sources of Effect Potential Effects Mitigation Net Effects Aquatic Habitat - Increased transport of fine sediment into

watercourse due to site clearing and construction activities.

- Installation of cofferdams to allow

overflow weir construction to be undertaken in the dry.

- Head-pond creation/filling.

- Sedimentation of riverbed; resulting in harmful habitat alteration.

- Temporary alteration/loss of aquatic habitat while

cofferdams are in place. Temporary loss of non-specialized aquatic habitat within cofferdam area.

- Reduced downstream flow during filling period resulting

in decreased wetted surface area.

- Altered habitat characteristics as head pond fills – reduced flow velocity, greater depth and larger surface area

- Erosion and sediment control plan implemented for all construction activities. - Cofferdam material will be removed from the watercourse following construction. - Head pond to be filled during high flow periods or slowly with ambient river flow reduced by no

more than 10% of instantaneous flow at the time of filling.

- Install replacement habitat works to offset losses of fast water habitat


- Short-term disruption of habitat use

in, and downstream of, overflow weir areas. Loss of benthic community within disturbed areas.

- No residual effect

- Residual effect anticipated until

replacement habitat takes over function of lost habitat.

Terrestrial Vegetation, including Wetlands

- Clearing for access roads, facilities, head ponds and transmission lines.

- Use of hazardous materials on site. - Generation of dust from vehicle

movement. - Head-pond filling.

- Permanent and temporary loss of terrestrial vegetation.

- Impacts to vegetation/wetlands due to spills of hazardous materials.

- Reduced growth or senescence in dust-covered plants. - Loss of small wetland immediately upstream of Big Falls.

- All areas to be cleared are to be identified and all activities restricted to work areas; in small clearing areas, individual trees to be removed will be flagged.

- Materials disturbed from clearing/grubbing are not to be pushed up against remaining vegetation.

- Equipment and materials storage areas and stockpiles will be kept away from residual trees in the study area.

- Trees to be felled into cleared areas. - Clearing and grubbing to be minimized and existing vegetation mat to be left wherever

possible. - Mitigation measures to prevent impacts on soils will also be effective at preventing impacts to

terrestrial vegetation. - Mitigation measures identified with respect to preventing impacts to air quality will also be

effective at preventing impacts to terrestrial vegetation. - Not possible to mitigate. Filled head pond will expand into embayments on west and east

shore and will provide replacement areas for wetland vegetation.

- Permanent loss of 8.6 ha of terrestrial vegetation, temporary loss of 0.5 ha of terrestrial vegetation.


mitigation. - No residual effect with effective

mitigation. - Short term residual effect until new

wetlands develop at head-pond operating level.

Wildlife - Clearing for access roads, facilities, and transmission lines.

- Head-pond filling.

- Loss of wildlife habitat. - Wildlife disturbance. - Incidental mortality. - Flooding of bird nests.

- Mitigation measures previously identified with respect to terrestrial vegetation will be effective at minimizing the amount of habitat lost due to clearing.

- Clearing, blasting, and filling will be schedule to occur outside of the spring and early summer

months (i.e. for birds: forest habitat – May 24 to July 31, wetland habitat – May 16 to July 23, and open habitat – May 24 to July 23) where possible.

- If clearing must occur within these time periods, a nest survey must be undertaken to identify and locate active nests. If active nests found, a mitigation plan must be developed and approved by Environment Canada.

- All work and workforce to be confined to the identified areas. - Equipment is to be removed from the site when no longer needed. - Workforce is to stay away from shrubs and tree cover where possible. - Construction vehicles will be confined to work areas and approved roads. - Speed limits to be enforced on project construction vehicles. Mitigation measures identified

with respect to wildlife disturbance will also minimize fatalities. Transmission line design (spacing, pole design, bird flappers/diverters) to consider potential impacts to avifauna.

- Head-pond filling to occur outside the breeding bird window (i.e., May 16 to July 31) where

possible. If filling is required during this time, a nest survey will be completed prior to filling.

- Residual effect associated with loss of 8.6 ha of wildlife habitat, and temporary loss of 0.5 ha of wildlife habitat.

- Short term residual effect. - Short term residual effect. - No residual effect following effective

mitigation.


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Environmental Component Sources of Effect Potential Effects Mitigation Net Effects

- Use of hazardous materials on site.

- Flooding of beaver lodges - Impacts to vegetation/wetlands due to spills of

hazardous materials.

- Beaver in head pond to be trapped, where possible, prior to filling of head pond. - Mitigation measures identified with respect to preventing impacts on soils will also be effective

at preventing impacts on wildlife.

- Short term residual effect until head pond recolonized.

- No residual effect following effective mitigation.

Species at Risk - Construction activities (clearing, blasting, excavation and head pond creation).

- Potential impacts on avian species at risk. - Mitigation measures previously identified with respect to wildlife will be effective at minimizing potential impacts to avian species at risk.


Employment/ Economic Opportunities

- General construction activities - Positive impact in local employment and economic benefit to local businesses.

- No mitigation required. Local labour and supplies will be used where possible. - Positive short term residual effect on local community.

Local Business - General construction activities . - Negative effect on resource-based tourism and recreational opportunities due to increased traffic on local roadways and construction activities at site.

Mitigation measures will be implemented to limit disturbance to the area and minimize effects to traffic on local roadways, resource use and recreation are: - staff and site visitors to remain within predetermined work areas - vehicles are to be equipped with effective muffler and exhaust systems - control of vehicle and equipment speed - soil stockpiles to be covered - dump trucks transporting soil/excavated material to be covered when warranted - temporary storage piles of fine materials to be worked from the downwind side - use of water spray dust suppression as necessary - vehicles and equipment not left to idle, running only when necessary - limited vehicles to existing trails and approved roads where possible.

- Short term residual effect.

Local Highways and Roads - Use of local highways and roadways during construction period.

- Increased vehicle traffic and potential delays on Highways 105, 657 and South Bay Road during the construction period

- Contractor work force and construction activities to be undertaken in compliance with Highway Traffic Act.

- Designate transportation routes to avoid tight turning areas and delays. - Check overhead lines to determine the requirement for temporary removal or relocation (the

appropriate utility will be contacted). - Use a police escort or security company to guide/accompany any oversize loads as

necessary. - Use flagmen (as required) to facilitate traffic flow and control


115-kV Hydro One Networks Inc. Transmission Line

- Interconnection of new transmission lines to existing transmission line network.

- Potential adverse effects to HONI’s existing transmission line.

- A connection impact assessment has been completed outlining required upgrades to be completed to the system prior to interconnection.


Emergency and Medical Services - Influx of personnel to the area during construction

- Increased personnel in the area may lead to an increase in use of emergency and medical services.

- No mitigation measures proposed. It is anticipated that local services will be equipped to ensure adequate emergency or medical services.


Crown Land Policy - Construction of proposed facilities on Crown land.

- Loss/alteration of alternative Crown land uses (e.g., recreation, etc) on proposed facility lands.

- No mitigation required. Waterpower is an accepted use of Crown Lands for the Red Lake Area.


Forest Resources - Project construction activities requiring travel on South Bay Road and clearing of forest resources

- Increased traffic on South Bay Road given its utilization by both forestry and project construction traffic

- Loss of a small amount of merchantable timber within the

SFL holder inventory.

Mitigation measures to reduce potential negative effects to traffic are discussed under Local Highways and Roads. Measures to address loss of merchantable timber include - a merchantable timber survey will be performed prior to clearing to determine the amount of

timber to be harvested - all merchantable timber to become the property of the Sustainable Forest License holder - wood that cannot be sold will be chipped and used as mulch during project restoration

activities. - the contractor may opt to burn slash, which will be completed in accordance with an MNR burn

permit.

- No residual effect - Small residual effect

Mineral Resources - Construction of the project. - Objection from mining claim holder that the project area be developed for waterpower

- Horizon Hydro will work with any claimants which overlap the proposed project area along with MNR and MNDM to ensure that the appropriate agreements are in place where required.

- No residual effect on mineral exploration and prospecting activities. Surface rights release obtained.

Hunting - General Construction Activities. - The holder of BMA RL-03-028 could experience reduced opportunities for bear hunting.

- The holder is to be contacted by Horizon Hydro or the Contractor and notified of the proposed construction activities that will occur during the bear hunting season (August15 to October 31).



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Environmental Component Sources of Effect Potential Effects Mitigation Net Effects Trapping - General Construction Activities. - Potential effect to harvest success within trapping area

RL-17 based on construction timing and location of Trapline.

- The holder of trapline RL-17 is to be contacted by Horizon Hydro or the Contractor and notified of the location and timing of construction activities.


Fishing - General Construction Activities. - Restriction of public access to the falls area - Safe, alternative access to the river will be provided during the construction of the project. If an alternative public access route to the upper or lower river is required during construction, it will be provided by the proponent. Access to areas outside the construction zone will be provided by means of a written request to Horizon for access to specific area, and a subsequent review (by Horizon or contractor) to ensure that area requested is not within work zone and/or could endanger a member of the public.


Canoeing/Kayaking - General Construction Activities. - Prohibition of the use of the portage route on the eastern shore of the Project, and disruption to the “wilderness” canoeing/kayaking experience in this area of the Trout Lake and Trout Lake River advanced lake and river travel canoe route.

- Place warning signs at the approach to the portage entrance to alert paddlers of construction activities including potential dangers at the site and directions for safe passage around the area.

- Relocate/upgrade any existing portages affected during construction to allow safe passage of paddlers during construction.

- Identify any area(s) for safe construction viewing. - Restrict access to the construction area via fencing and gates to ensure public safety.


Tourism - General Construction Activities. - Potential adverse effects to the aquatic and terrestrial environments could affect tourism at the outposts, camps and lodges existing upstream and downstream of the study area.

- Limited access to Big Falls as a scenic attraction.

- Mitigation measures have been proposed to control potential adverse impacts to the aquatic and terrestrial environments, so that downstream tourism resources are not affected.

- Flows will be unaffected during the construction process, and access to view the falls will be possible, although some areas (active work/excavation areas) will be ‘off limits’ to protect public safety.

- No residual effect. - No residual effect. .

Lands and Resources Used for Traditional Purposes by First Nations

- General Construction Activities. - Potential conflict with traditional use of the project area. - Wild rice bed in head pond inundated during head-pond

filling - Potential loss of medicinal plants due to project

development.

- No conflict with traditional use has been identified, however mitigation measures to eliminate/reduce potential impacts to various environmental components, including wildlife, aquatic biota, resources use, etc, are presented above.

- Horizon will develop plans for replacement of the wild rice bed during the final design stage, and will work with Aboriginal communities to re-establish wild rice in the head pond.

- Horizon will walk the Project area with an Aboriginal community expert in traditional medicinal plants to determine potential impacts. If necessary, Horizon will work with Aboriginal communities to develop a mitigation plan for implementation prior to construction.


Archaeological and Heritage Resources

- General Construction Activities. - Potential discovery of human remains or other archaeologically or culturally significant material.

- Should human remains be identified during the construction, operations or decommissioning of the project, all work in the vicinity of the discovery will be halted immediately, as required by the Ontario Ministry of Culture regulations under the Ontario Heritage Act.

- Notification will be made to the Ontario Provincial Police, or local police, who will conduct a site investigation and contact the district coroner.

- Notification will also be made to the Development Plans Review Office, Ontario Ministry of Culture, Heritage and Libraries Branch, Heritage Operations Unit, 400 University Ave, 4th Floor, Toronto, ON, M7A 2R9, and the Registrar of Cemeteries, Ontario Ministry of Consumer and Commercial Relations.

- Work would be halted if any artifacts are found until the site can be investigated and cleared by a licensed archaeologist.

- Aboriginal communities will be notified of any aboriginal artifacts uncovered during the construction process.



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Environmental Component Sources of Effect Potential Effects Mitigation Net Effects Construction Site Safety - All Construction Activities. - Potential hazards to workers safety. - Completion of safety training program by all workers.

- Strict adherence to the Ministry of Labour occupational health and safety regulations pertaining to construction sites regarding worker safety.

- First aid equipment, as appropriate to the activity to be maintained on site. - Material Safety Data Sheets for any hazardous material used on site to be available close to

the location where the material is used and stored. - An accident and emergency spill response plan. - Spill containment and clean-up materials on site. - Training to deal with spill situations.


Public Safety in the Vicinity of the Project

- All Construction Activities. - Public use in the vicinity of the project during construction may result in public safety concerns.

- Prevent public access to the construction site through use of gate(s), and security procedures. - Post signage to notify the public of construction in the area, and alternate routing around the

site. - Use flagmen as required to ensure that traffic on access roads is controlled. - Drive construction vehicles in a proper manner and respect all traffic laws, regulations, and

company policies.


Waste Management - General Construction Activities - Generation of solid wastes including domestic waste, and construction waste in addition to sewage wastes.

- All solid and sewage wastes are to be contained and hauled off site by a designated hauler throughout the construction period. All domestic and construction waste will be transported to an MOE licensed landfill by a licensed hauler.

- Store hazardous wastes in double-walled containment tanks or impervious berms until disposal off site at a registered facility.

- Store solid wastes on site prior to disposal off site at local registered disposal facilities - Practice reuse and recycling whenever possible. - Securely contain domestic waste to avoid a nuisance bear situation prior to disposal off site

(approximately twice weekly during summer months).


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