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AQUATIC ENVIRONMENT ASSESSMENT OF ENVIRONMENTAL EFFECTS
TECHNICAL SUPPORT DOCUMENT NEW NUCLEAR - DARLINGTON
ENVIRONMENTAL ASSESSMENT NK054-REP-07730-00013 Rev 000
Submitted To:
Ontario Power Generation Inc. Prepared By:
Golder Associates and SENES Consultants Limited
September 2009
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effects
Ontario Power Generation Inc. Technical Support Document
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EXECUTIVE SUMMARY
Ontario Power Generation (OPG) was directed by the Ontario Minister of Energy in June 2006
to begin the federal approvals process, including an environmental assessment (EA), for new
nuclear units at an existing site. OPG has begun this process for a new nuclear power generating
station at the Darlington Nuclear site (DN site).
This Assessment of Environmental Effects Technical Support Document (TSD) relates to the
Aquatic Environment (AE), and is one of a series of related documents prepared by the EA
Consulting Team. Following on the separate series of Existing Conditions TSDs, this TSD
describes the changes and effects in the context of baseline conditions that are considered likely
to occur as a result of implementing the Project.
The AE component is comprised of aquatic habitat and aquatic biota. Baseline or existing
conditions were described in the Aquatic Environment Existing Conditions TSD, including on-
site and Lake Ontario nearshore aquatic features. Selection of Valued Ecosystem Components
(VECs) focused on habitats, and included Darlington Creek and the Lake Ontario nearshore to
address physical effects on these features during the Site Preparation and Construction phase,
and aquatic biota, including forage species, benthivorous fish and predatory fish. The indicator
species for the Darlington Creek VEC is white sucker. VEC indicator species for the Lake
Ontario nearshore and aquatic biota VECs include a range of species and groups for which there
may be concern during the Site Preparation and Construction phase and the Operation and
Maintenance phase. These include:
Benthic invertebrates;
Fish species: Round goby; Emerald shiner; Alewife; White sucker; Round whitefish;
Lake sturgeon; American eel; Lake trout; and Salmonid sportfish.
The assessment addressed two primary effects pathways, related to physical changes to aquatic
habitat and organism-level effects involving intake losses and thermal discharge.
During Site Preparation and Construction, on-site and Lake Ontario nearshore aquatic habitats
will be physically altered to varying degrees by changes to grades, substrate and drainage
patterns. Mitigation will focus on a comprehensive fish habitat mitigation, restoration and
compensation strategy that will be developed at a more advanced design stage to address
Fisheries Act (FA) requirements and, more broadly, to maintain functioning aquatic habitat on
site that is integrated with wetland and terrestrial habitats. Preliminary discussions have already
been initiated with the Department of Fisheries and Oceans (DFO), Ontario Ministry of Natural
Resources (OMNR) and local conservation groups.
During the Operations and Maintenance Phase, withdrawal of cooling water will cause some fish
impingement and entrainment of fish and invertebrates. Cooling water discharge will change
water temperatures in a portion of the Lake Ontario nearshore, primarily within a limited mixing
zone. In-design mitigation of both intake and discharge effects includes siting in relatively
unproductive areas of the nearshore. Additional mitigation of intake losses will include a porous
veneer intake structure for once-through cooling or other fish deterrent strategies for a cooling
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tower intake. The discharge, in either case, will be designed as a diffuser to minimize thermal
effects.
As proven in-design mitigation will be implemented to address operational effects, the mitigation
of habitat effects related to Site Preparation and Construction appears to be the main AE
challenges to implementing the Project. OPG and consultants are currently in discussion with
DFO and other stakeholders concerning fish habitat losses and credible compensation options
have been identified, and are summarized in Appendix B.
In accordance with DFO Policy of the Management for Fish Habitat (DFO 1986), with specific
reference to the principle of ‘No Net Loss of the Productive Capacity of Fish Habitat’, OPG
agrees to undertake measures to compensate for and mitigate against, the loss of fish habitat
arising from the New Nuclear at Darlington (NND) Project. OPG has initiated the process by
submitting an Application for Authorization for Works or Undertakings Affecting Fish Habitatsto DFO (September 30, 2009) and will continue to work with DFO staff to complete the
compensation plan which will be incorporated into a subsection 35(2) authorization of the
Fisheries Act (FA). The plan will include components that will also address the requirements
under section 32 of the FA, if necessary, that states no person shall destroy fish by any means
other than fishing except as authorized by the Minister.
AE selected bounding scenarios from the four development scenarios and three reactor operation
scenarios described in the Scope of the Project for EA Purposes TSD. For the Site Preparation
and Construction Phase, Site Development Scenario 1, Four ACR 1000 Reactors with Once-
Through Cooling, were chosen. Potential interactions and their resolution with respect to
assessment and mitigation included:
Bridge crossing of the main branch of Darlington Creek will be mitigated by following
the applicable DFO Operational Statement, or aligning the access road further to the
west, resulting in negligible residual effect;
Loss of Treefrog, Polliwog and Dragonfly ponds will be mitigated by restoration of
aquatic habitat within new on-site drainage features, resulting in negligible residual
effect;
Loss of portions of intermittent tributaries to Darlington Creek will be mitigated by
restoration within reconfigured site drainage at the north tributary (which may remain
connected to Darlington Creek) and compensation within site drainage channels within
the south tributary (which may be re-directed towards Lake Ontario). Negligible residual
effects will result;
Alteration/disruption of Coot’s Pond will be avoided to the extent practicable and any
affected areas of the pond will be restored, resulting in negligible residual effects;
Alteration of upper portions of an intermittent tributary to Lake Ontario near Coot’s Pond
will be mitigated by restoration of habitat in on-site drainage courses, resulting in
negligible residual effect;
Lake infill (approximately 40 hectares) in front of the Darlington Nuclear Generating
Station (DNGS) and New Nuclear Darlington (NND) sites will be addressed by fish
habitat compensation that will be designed and negotiated with the agencies at a later
stage of Project design, resulting in negligible residual effect;
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Blasting and excavation (approximately 1.1 hectares) for the porous veneer intake will
follow DFO guidelines for the use of explosives to minimize incidental fish losses,
resulting negligible residual effect; and
Blasting and excavation (cumulative area of approximately 0.7 hectares) for diffuser
ports will follow DFO guidelines for the use of explosives to minimize incidental fish
losses, resulting negligible residual effect.
For the Operation and Maintenance Phase, Reactor Operations Scenario 1, Four ACR-1000
Reactors, were chosen as the bounding scenario as it involves the once-through cooling water
system. Potential interactions included:
Impingement and entrainment (I&E) of aquatic organisms, particularly fish (adults,
juvenile, eggs and larvae). I&E losses will be mitigated by the use of a lakebottom porous
veneer intake structure sited in approximately 10 meters depth of water in the Lake
Ontario nearshore. This configuration has proven successful at DNGS and is expected to
result in negligible residual effects at NND;
Thermal effects on habitat suitability and aquatic organisms will be mitigated by the use
of a lakebottom diffuser sited in approximately 10-20 meters of water in the Lake Ontario
nearshore. This configuration has proven successful at DNGS and is expected to result in
negligible residual effects at NND; and
Nuisance nutrient and algae conditions created in the nearshore by the lake infill
configuration will be mitigated, if necessary, according to an adaptive management
strategy that will monitor for the incidence of algae problems and will determine
management strategies that will result in negligible residual effects.
In addition, thermal effects of an alternative once-through cooling scenario involving the
Pressurized Water Reactor (PWR) which has an increased discharge water temperature as high
as 15.6oC and a flow rate of 135 m
3/s was addressed. However, as Surface Water Environment
(SWE) concluded that a similar mixing zone and thermal plume would occur, it was considered
to be bounded by Reactor Operations Scenario 1, Four ACR-1000 Reactors, with a maximum
discharge temperature of 9oC and a flow rate of 250 m
3/s for AE purposes. Negligible residual
thermal effects were predicted.
AE also addressed fish losses associated with a cooling tower option. Thermal effects of the
cooling tower discharge were considered to be bounded by the assessment of once-through
cooling. Fish losses, although bounded by the once-through scenario, were discussed for
comparison. Fish losses associated with the cooling tower option were lower than those
associated with once-through cooling, owing primarily to its much reduced water intake rate.
Similar to the once-through option, the cooling tower option was also expected to result in
negligible residual I&E effects.
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TABLE OF CONTENTS
Page No.
EXECUTIVE SUMMARY ............................................................................................................ 1
1. INTRODUCTION ........................................................................................................... 1-1
1.1 Background .......................................................................................................... 1-1
1.1.1 The New Nuclear - Darlington Project .................................................... 1-1
1.1.2 The New Nuclear - Darlington Environmental Assessment.................... 1-2
1.2 Technical Support Document (TSD) ................................................................... 1-2
1.3 Description of the Aquatic Environment Component.......................................... 1-3
1.3.1 Aquatic Habitat VECs.............................................................................. 1-4
1.3.2 Aquatic Biota VECs (Forage Species, Benthivorous Fish and
Predatory Fish)......................................................................................... 1-5
2. EFFECTS ASSESSMENT METHODOLOGY .............................................................. 2-1
2.1 Assessment Framework ....................................................................................... 2-1
2.2 Assessment Basis, Spatial Boundaries, Methods and Criteria............................. 2-2
2.2.1 Project Basis for the Assessment ............................................................. 2-2
2.2.2 Spatial Boundaries for the Assessment.................................................... 2-3
2.2.3 Analytical Methods for the Assessment .................................................. 2-8
2.2.4 Criteria for the Assessment...................................................................... 2-9
2.3 Process Steps for Determination of Likely Environmental Effects ..................... 2-9
2.3.1 Detailed Screening for Potential Project-Environment Interactions........ 2-9
2.3.2 Evaluation for Likely Measurable Changes in the Environment............. 2-9
2.3.3 Assessment of Likely Effects on the Environment................................ 2-11
2.3.4 Consideration of Mitigation and Determination of Likely Residual
Effects .................................................................................................... 2-11
3. ASSESSMENT AND MITIGATION OF ENVIRONMENTAL EFFECTS.................. 3-1
3.1 Detailed Screening for Potential Project-Environment Interactions.................... 3-1
3.2 Evaluation for Likely Change to the Environment .............................................. 3-6
3.2.1 Site Preparation and Construction Phase ................................................. 3-7
3.2.1.1 Mobilization and Preparatory Work and Excavation and Grading3-7
3.2.1.2 Marine and Shoreline Works - Lake Infill ................................... 3-8
3.2.1.3 Construction of Intake and Discharge Structures......................... 3-9
3.2.1.4 Management of Stormwater ......................................................... 3-9
3.2.2 Operation and Maintenance Phase........................................................... 3-9
3.2.2.1 Operation of Condenser Circulating Water, Service Water and
Cooling Systems........................................................................... 3-9
3.3 Assessment of Likely Effects on the Environment ............................................ 3-10
3.3.1 Site Preparation and Construction Phase ............................................... 3-10
3.3.1.1 Darlington Creek Crossing......................................................... 3-10
3.3.1.2 Removal of Upper Reaches of Intermittent Tributaries to
Darlington Creek ........................................................................ 3-11
3.3.1.3 Removal of On-Site Ponds......................................................... 3-12
3.3.1.4 Alteration/Disruption of Coot’s Pond ........................................ 3-15
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3.3.1.5 Alteration of Upper Reaches of Intermittent Lake Ontario
Tributary..................................................................................... 3-16
3.3.1.6 Lake infill ................................................................................... 3-16
3.3.1.7 Construction of Intake and Discharge Structures....................... 3-21
3.3.2 Operation and Maintenance Phase......................................................... 3-23
3.3.2.1 Impingement and Entrainment ................................................... 3-23
3.3.2.2 Impingement............................................................................... 3-23
3.3.2.3 Entrainment ................................................................................ 3-30
3.3.2.4 Thermal Discharge: Once-Through Cooling System................. 3-32
3.3.2.5 Comparison of Weekly Maximum Hourly Temperatures (WMHT)
to Round Whitefish Temperature Benchmarks.......................... 3-37
3.3.2.6 Thermal Discharge: Cooling Tower Option............................... 3-43
3.3.2.7 Lake Infill Structure ................................................................... 3-43
3.3.3 Summary of Effects Advanced for Mitigation....................................... 3-44
3.4 Consideration of Mitigation and Determination of Likely Residual Effects ..... 3-44
3.4.1 Access Road Crossing of Darlington Creek .......................................... 3-47
3.4.2 Removal of On-Site Ponds (Treefrog, Dragonfly and Polliwog
Ponds) .................................................................................................... 3-47
3.4.3 Removal of Upper Reaches of Intermittent Tributaries to
Darlington Creek.................................................................................... 3-48
3.4.4 Alteration/Disruption of Coot’s Pond.................................................... 3-48
3.4.5 Alteration of Upper Reaches of Intermittent Lake Ontario
Tributary ................................................................................................ 3-49
3.4.6 Lake Infill............................................................................................... 3-49
3.4.7 Construction of Intake and Discharge Structures .................................. 3-49
3.4.8 Impingement and Entrainment............................................................... 3-50
3.4.9 Thermal Discharge................................................................................. 3-50
3.5 Potential Consequence of Climate Change on Predicted Effects ...................... 3-50
3.6 Section 35(2) Proposed Compensation Plan...................................................... 3-51
3.7 Ecosystem Dynamics –Invasive Species ........................................................... 3-52
4. REFERENCES ................................................................................................................ 4-1
LIST OF APPENDICES
APPENDIX A NEW NUCLEAR – DARLINGTON – EA BASIS TABLE A-1
APPENDIX B COMPENSATION DEVELOPMENT OPTIONS TABLE B-1
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LIST OF FIGURES Page No.
2.2-1 Site Study Area.............................................................................................................. 2-5
2.2-2 Local Study Area........................................................................................................... 2-6
2.2-3 Regional Study Area ..................................................................................................... 2-7
3.3.1-1 DN Site Aquatic Features............................................................................................ 3-14
3.3.1-2 Distribution of Sediment Types Identified by Underwater Video within the
Proposed Lake Infill Area ........................................................................................... 3-18
3.3.1-3 Benthic Invertebrate Sampling Locations within the Proposed Lake Infill Area ....... 3-18
3.3.2-1 Weekly Maximum Hourly Temperatures (1993-1996) .............................................. 3-42
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LIST OF TABLES
Page No.
2.3.2-1 Range and Relevance of Potential Change in the AE ................................................. 2-10
3.1-1 Potential Project-Environment Interactions in the AE.................................................. 3-2
3.2-1 Evaluation Criteria used in the AE................................................................................ 3-6
3.3.2-1 DNGS Impingement Loss Estimates (1993-1996, 2006-2007) .................................. 3-24
3.3.2-2 Comparison of Entrainment and Impingement Estimated Losses at Different
Plants on the Great Lakes............................................................................................ 3-27
3.3.2-3 Estimated Total Annual Impingement Losses ............................................................ 3-28
3.3.2-4 Estimated Alewife Impingement for the Cooling Tower Option................................ 3-29
3.3.2-5 MWAT above Ambient Values along the Perimeter of the Mixing Zone .................. 3-35
3.3.2-6 Maximum Weekly Average Temperatures (°C) for Round Whitefish ....................... 3-38
3.3.2-7 Weekly Maximum Hourly Temperatures (WMHT) from the DNGS Thermal Plume
Study Data ................................................................................................................... 3-39
3.3.2-8 Mean Air Temperatures Recorded from Environment Canada’s Weather
Station at Pearson International Airport (°C).............................................................. 3-41
3.3.2-9 Total Precipitation Recorded from Environment Canada’s Weather Station
at Pearson International Airport (mm) ........................................................................ 3-41
3.4-1 Summary of Likely Environmental Effects, In-Design Mitigation Measures
and Mitigation Recommendations .............................................................................. 3-45
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SPECIAL TERMS
Units
kg kilogram
cm centimetre
oC degrees Celsius
ft/s feet per second
m metre
m/s metre per second
m3/s cubic metre per second
Abbreviations and Acronyms
AE Aquatic Environment
CEAA Canadian Environmental Assessment Act
CCW Condenser Circulating Water
CLOCA Central Lake Ontario Conservation Authority
CN Canadian National Railway Company
CNSC Canadian Nuclear Safety Commission
DEER Darlington Ecological Effects Review
DFO Fisheries and Oceans Canada
DN Darlington Nuclear
DNGS Darlington Nuclear Generating Station
EA Environmental Assessment
EIS Environmental Impact Statement
ERA Ecological Risk Assessment
FA Fisheries Act
HAAT Habitat Alteration Assessment Tool
HADD Harmful Alteration, Disruption or Destruction of Fish Habitat
I&E Impingement and entrainment
LSA Local Study Area
MOE Ontario Ministry of Environment
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MWAT Maximum Weekly Average Temperature
WMHT Weekly Maximum Hourly Temperature
NND New Nuclear – Darlington
OMNR Ontario Ministry of Natural Resources
OPG Ontario Power Generation Inc.
Project The Site Preparation, Construction and Operation and Maintenance of New
Nuclear - Darlington
R+R Radiation and Radioactivity Environment
RSA Regional Study Area
SSA Site Study Area
SWE Surface Water Environment
SWM Stormwater Management
TSD Technical Support Document
USEPA United States Environmental Protection Agency
VEC Valued Ecosystem Component
YOY Young of Year Fish
Glossary of Terms
Aboriginal Rights: Those rights of Aboriginal Peoples which are not found in treaties or
land claim agreements.
Adaptive Management
Plan:
It is the integration of design, management, and monitoring to
systematically test assumptions in order to adapt and learn.
Aquatic Environment: The components related to, living in, or located in or on water or the
beds or shores of a water body, including but not limited to all
organic and inorganic matter, and living organisms and their habitat,
including fish habitat, and their interacting natural systems.
Baseload: The minimum amount of electric power delivered or required at a
steady rate over a given period of time.
Boiler: A device for generating steam for power, processing, or heating
purposes, or for producing hot water for heating purposes or hot
water supply. Heat from an external combustion source is
transmitted to a fluid contained within the tubes in the boiler shell.
This fluid is delivered to an end-use at a desired pressure,
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temperature, and quality.
Conservation: Steps taken to cause less energy to be used than would otherwise be
the case. These steps may involve improved efficiency, avoidance of
waste, reduced consumption, etc. They may involve installing
equipment (such as a computer to ensure efficient energy use),
modifying equipment (such as making a boiler more efficient),
adding insulation, changing behaviour patterns, etc.
Ecological Risk
Assessment:
The process that evaluates the likelihood that adverse ecological
effects may occur or are occurring as a result of exposure to one or
more stressors. This definition recognizes that a risk does not exist
unless: (1) the stressor has an inherent ability to cause adverse
effects, and (2) it is coincident with or in contact with the ecological
component long enough and at sufficient intensity to elicit the
identified adverse effects(s).
Efficiency: The efficiency of a generating unit in converting the thermal energy
contained in a fuel source to electrical energy. It is expressed as a
percentage and equals 3.6 divided by the heat rate of the unit (in
GJ/MWh).
Electrical Power: The rate of delivery of electrical energy and the most frequently used
measure of capacity. The typical basic units of electrical power are
the kilowatt (kW) and megawatt (MW).
Energy: The capability for doing work (potential energy) or the conversion of
this capability to motion (kinetic energy). Energy has several forms,
some of which are easily convertible and can be changed to another
form useful for work. Most of the world’s convertible energy comes
from fossil fuels that are burned to produce heat that is then used as
a transfer medium to mechanical or other means in order to
accomplish tasks.
Entrainment: Occurs when aquatic invertebrates, fish eggs and fish larvae are
drawn into a water intake and cannot escape.
Environmental
Assessment:
A process for identifying project and environment interactions,
predicting environmental effects, identifying mitigation measures,
evaluating significance, reporting and following-up to verify
accuracy and effectiveness. Environmental Assessment is used as a
planning tool to help guide decision-making, as well as project
design and implementation.
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Environmental Effect: As defined in the Canadian Environmental Assessment Act.
Exclusion Zone: A parcel of land within or surrounding a nuclear facility on which
there is no permanent dwelling and over which a licensee has the
legal authority to exercise control (from Class I Nuclear Facilities
Regulations).
Facility: An existing or planned location or site at which prime movers,
electric generators, and/or equipment for converting mechanical,
chemical, and/or nuclear energy into electric energy are, or will be,
situated. A facility may contain generating units of either the same
or different prime mover types.
Fuel: Any substance that can be burned to produce heat. It is also a
material that can be fissioned in a nuclear reaction to produce heat.
Generating Unit: Any combination of physically connected reactor(s), boiler(s),
combustion turbine(s), or other prime mover(s), generator(s), and
auxiliary equipment operated together to produce electricity.
Generating Plant: A facility containing one or more generating units.
Generation: The process of producing electrical energy by transforming other
forms of energy.
Impingement: Occurs when an entrapped fish is held in contact with the intake
screen and is unable to free itself.
In Situ: In its original place; in position; in situ recovery refers to various
methods used to recover deeply buried bitumen deposits, including
steam injection, solvent injection, and firefloods.
Joint Review Panel: A Review Panel appointed pursuant to the Canadian Environmental
Assessment Act.
Kilowatt (kW): A standard unit used to measure electric power, equal to 1,000 watts.
A kilowatt can be visualized as the total amount of power required to
light ten 100-watt light bulbs.
Local Study Area
(LSA):
Land and portions of Lake Ontario beyond the SSA where there is a
reasonable potential for obvious, readily-understood and mitigable
environmental effects related to the Project.
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Megawatt (MW): One million watts.
Nuclear Power Plant: A generating plant in which heat produced in a nuclear reactor by
the fissioning of nuclear fuel is used to drive a steam turbine.
Porous Veneer Intake: A specially designed water intake, which incorporates fish protection
features, for delivery of cooling water to the power plant.
Project: Site Preparation, Construction and Operation of New Nuclear –
Darlington (NND).
Proponent: Ontario Power Generation Inc. (OPG).
Radioactive nuclides /
radionuclides:
Is an atom with an unstable nucleus. The radionuclide undergoes
radioactive decay by emitting a gamma ray(s) and/or subatomic
particles. Radionuclides are often referred to by chemists and
biologists as radioactive isotopes or radioisotopes, and play an
important part in the technologies that provide us with food, water
and good health. Radionuclides may occur naturally, but can also be
artificially produced.
Regional Study Area
(RSA):
Land and portions of Lake Ontario beyond the LSA that could
reasonably be considered relevant in the assessment of more wide-
spread environmental effects, and wherein there is a potential for
cumulative and socio-economic effects related to the Project.
Site Study Area (SSA): The property, including land and portions of Lake Ontario, on which
the Project is located and which is under the care and control of
OPG; plus those adjacent areas that are clearly associated with it as a
result of biophysical connection.
Species at Risk: As defined in the federal Species at Risk Act.
Sustainability: Indicator selected with the aim to provide information on the essence
of sustainable development; it may refer to systemic characteristics
such as carrying capacities of the environment, or it may refer to
interrelations between economy, society, and the environment.
Terrestrial
Environment:
The components related to, living on, or located on the Earth’s land
areas, including but not limited to all organic and inorganic matter,
living organisms and their habitat, and their interacting natural
systems.
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Thermal Discharge
(Diffuser):
Discharge of waste heat to the lake environment using a specially
designed pipe with diffuser ports to minimize impacts to the
environment.
Turbine: A machine for generating rotary mechanical power from the energy
of a stream of fluid (such as water, steam, or hot gas). Turbines
convert the kinetic energy of fluids to mechanical energy through the
principles of impulse or reaction, or a mixture of the two.
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LIST OF TECHNICAL SUPPORT DOCUMENTS (TSDs)
Atmospheric Environment Existing Environmental Conditions TSD – SENES Consultants Limited
Atmospheric Environment Assessment of Environmental Effects TSD – SENES Consultants Limited
Surface Water Environment Existing Environmental Conditions TSD – Golder Associates Limited
Surface Water Environment Assessment of Environmental Effects TSD – Golder Associates Limited
Aquatic Environment Existing Environmental Conditions TSD – SENES Consultants Limited and Golder
Associates Limited
Aquatic Environment Assessment of Environmental Effects TSD - SENES Consultants Limited and Golder
Associates Limited
Terrestrial Environment Existing Environmental Conditions TSD – Beacon Environmental
Terrestrial Environment Assessment of Environmental Effects TSD – Beacon Environmental
Geological and Hydrogeological Environment Existing Environmental Conditions TSD – CH2M HILL Canada
Limited and Kinectrics Incorporated
Geological and Hydrogeological Environment Assessment of Environmental Effects TSD – CH2M HILL Canada
Limited
Land Use Existing Environmental Conditions TSD – MMM Group Limited
Land Use Assessment of Environmental Effects TSD – MMM Group Limited
Traffic and Transportation Existing Environmental Conditions TSD – MMM Group Limited
Traffic and Transportation Assessment of Environmental Effects TSD – MMM Group Limited
Radiation and Radioactivity Environment Existing Environmental Conditions TSD – AMEC NSS
Radiation and Radioactivity Environment Assessment of Environmental Effects TSD – SENES Consultants Limited
and AMEC NSS
Socio-Economic Environment Existing Environmental Conditions TSD - AECOM
Socio-Economic Environment Assessment of Environmental Effects TSD - AECOM
Physical and Cultural Heritage Resources Existing Environmental Conditions TSD – Archaeological Services
Incorporated
Physical and Cultural Heritage Resources Assessment of Environmental Effects TSD – Archaeological Services
Incorporated
Ecological Risk Assessment and Assessment of Effects on Non-Human Biota TSD – SENES Consultants Limited
Scope of Project for EA Purposes TSD – SENES Consultants Limited
Emergency Planning and Preparedness TSD – SENES Consultants Limited and KLD Associates Incorporated
Communications and Consultation TSD – Ontario Power Generation Incorporated
Aboriginal Interests TSD – Ontario Power Generation Incorporated
Human Health TSD – SENES Consultants Limited
Malfunctions, Accidents and Malevolent Acts TSD – SENES Consultants Limited
Nuclear Waste Management TSD – Ontario Power Generation Incorporated
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1. INTRODUCTION
1.1 Background
Ontario Power Generation (OPG) was directed by the Ontario Minister of Energy in June 2006
to begin the federal approvals process, including an environmental assessment (EA), for new
nuclear units at an existing site. OPG initiated this process, and in September 2006 submitted an
application for a Licence to Prepare Site the Canadian Nuclear Safety Commission (CNSC) for a
new nuclear power generating station at the Darlington Nuclear site (DN site), located in the
Municipality of Clarington on the north shore of Lake Ontario in the Region of Durham. The
DN site is currently home to Darlington Nuclear Generating Station (DNGS), a 4-unit plant, the
first unit of which was commissioned by OPG in 1990. It remains under OPG ownership and
operational control.
Before any licensing decision can be made concerning the new nuclear generating station, an EA
must be performed to meet the requirements of the Canadian Environmental Assessment Act(CEAA) and be documented in an Environmental Impact Statement (EIS). An EIS is a document
that allows a Joint Review Panel, regulators, members of the public and Aboriginal groups to
understand the Project, the existing environment and the potential environmental effects of the
Project. Guidelines for the preparation of the EIS were prepared by the Canadian Environmental
Assessment Agency (the CEA Agency) and the CNSC (in consultation with Department of
Fisheries and Oceans Canada (DFO), the Canadian Transportation Agency and Transport
Canada). The Guidelines require that the proponent prepare the EIS and support it with detailed
technical information which can be provided in separate volumes. Accordingly, OPG has
conducted technical studies that will serve as the basis for the EIS. These technical studies are
documented in Technical Support Documents (see Section 1.2 below).
1.1.1 The New Nuclear - Darlington Project
New Nuclear Darlington (NND), a new generating station, is proposed to be located primarily on
the easterly one-third (approximately) of the DN site, with reactor buildings and other related
structures located south of the Canadian National Railway Company (CN) rail line. The
proposed Project involves the construction and operation of up to four nuclear reactor units
supplying up to 4,800 MW of electrical capacity to meet the baseload electrical requirements of
Ontario. The proposed Project will include:
Preparation of the DN site for construction of the new nuclear facility;
Construction of the NND nuclear reactors and associated facilities;
Construction of the appropriate nuclear waste management facilities for storage and
volume reduction of waste;
Operation and maintenance of the NND nuclear reactors and associated facilities for
approximately 60 years of power production (i.e., for each reactor);
Operation of the appropriate nuclear waste management facilities; and,
Development planning for decommissioning of the nuclear reactors and associated
facilities, and eventual turn-over of the site to other uses.
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For EA planning purposes, the following temporal framework has been adopted for the Project:
Project Phase Start Finish
Site Preparation and Construction 2010 2025
Operation and Maintenance 2016 2100
Decommissioning and Abandonment 2100 2150
1.1.2 The New Nuclear - Darlington Environmental Assessment
The EA considers the three phases of the NND Project (i.e., Site Preparation and Construction,
Operation and Maintenance, and Decommissioning and Abandonment) extending over
approximately 140 years. In doing so, it addresses:
The need for, and purpose of the Project;
Alternatives to the Project;
Alternative means of carrying out the Project that are technically and economically
feasible, and the environmental effects of such alternatives;
The environmental effects of the Project including malfunctions, accidents and
malevolent acts, and any cumulative effects that are likely to result from the Project in
combination with other projects or activities that may be carried out;
Measures to mitigate significant adverse environmental effects that are technically and
economically feasible;
The significance of residual (after mitigation) adverse environmental effects;
Measures to enhance any beneficial environmental effects;
The capacity of renewable resources that are likely to be significantly affected by the
project, to meet the needs of the present and the future;
The requirements of a follow-up program in respect of the Project;
Consideration of community knowledge and Aboriginal traditional knowledge; and,
Comments that are received during the EA.
1.2 Technical Support Document (TSD)
The EA studies were carried out and are documented within a framework of individual aspects or
“components” of the environment. The environmental components are:
Atmospheric Environment;
Surface Water Environment (SWE);
Aquatic Environment (AE);
Terrestrial Environment (TE);
Geological and Hydrogeological Environment;
Land Use;
Traffic and Transportation;
Radiation and Radioactivity Environment (R+R);
Socio-Economic Environment;
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Physical and Cultural Heritage Resources;
Aboriginal Interests;
Health - Human; and,
Health – Non-Human Biota (Ecological Risk Assessment).
This Technical Support Document (TSD) describes the assessment of effects of the Project on
the aquatic component of the environment. It has been prepared by Golder Associates and
SENES Consultants Limited, the member firm of the EA Consulting Team with technical
responsibility for the AE component of the environment. This TSD is one of a series of related
documents describing different aspects of the overall effects assessment, one for each
environmental component.
A separate series of TSDs (i.e., Existing Environmental Conditions TSDs), one for each
environmental component, describes the baseline conditions throughout the study areas relevant
to the Project, including Valued Ecosystem Components (VECs). A preliminary screening of
potential Project-environment interactions for each environmental component was carried out
during the baseline characterization program to focus those studies on relevant aspects of the
existing environment.
In most cases, separate TSDs have been prepared to describe existing conditions and likely
effects of the Project. However, for some environmental components the description of existing
environmental conditions and the assessment of environmental effects have been combined
within one TSD.
A number of other TSDs have also been prepared to address related subjects in support the EA.
These include, but are not necessarily limited to:
Scope of the Project for EA Purposes;
Emergency Planning and Preparedness;
Communications and Consultation;
Malfunctions, Accidents and Malevolent Acts; and,
Nuclear Waste Management.
1.3 Description of the Aquatic Environment Component
The AE is defined as aquatic habitat and aquatic biota. It is comprised of the following
environmental subcomponents that represent fundamental constituent features that are potentially
susceptible to effects of the Project and/or are pathways or mechanisms for transfer of an effect
to another environmental component. Aquatic habitat and aquatic biota are defined as:
Aquatic habitat includes the physical areas of Lake Ontario, tributary watercourses and
ponds within the study area. In these different areas, it is characterized by conditions of
flow, current, bathymetry, temperature, substrates, and water quality that influence its
status with respect to the Fisheries Act (FA) (DFO 1986) (i.e., whether it is fish habitat,
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and of what type). Because the areas occupied by existing and future intake forebays will be
artificially separated from Lake Ontario, they were not included in the assessment.
Aquatic biota includes the communities of underwater plants and animals that occupy
the aquatic habitat defined above. These include, depending on habitat conditions,
periphyton, aquatic macrophytes, phytoplankton, benthic invertebrates, zooplankton, and
fishes. Aquatic biota may also include rare, vulnerable, threatened and endangered
aquatic species.
(For this assessment, emphasis has been placed on interactions related to benthic
invertebrates and fish, as these organisms are integrators of a diverse range of
environmental conditions, their responses are generally understood and they tend to be
the subject of management and conservation objectives.)
(The effects of releases of potentially toxic substances is not addressed in this TSD, but
rather, are considered in the ERA – Environmental Effects Assessment TSD and the R+R
– Environmental Effects Assessment TSD.)
1.3.1 Aquatic Habitat VECs
Aquatic habitat VECs were chosen to focus the assessment on the Site Preparation and
Construction Phase of the Project works and activities that will result in alterations to on-site
drainage features and portions of the Lake Ontario nearshore. Agency review and permits will be
required, including Fisheries and Oceans Canada (DFO) or Central Lake Ontario Conservation
Authority (CLOCA) authorization and Ontario Ministry of Natural Resources (OMNR) permits,
so it is considered useful to discuss effects in the EA in habitat terms and to consider fish habitat
compensation requirements as the likely mitigation measures that will be required beyond those
already incorporated in the Project design as effects management features. It is too early in the
design process to define fish habitat effects of the Project in sufficient detail to completely
negotiate a section 35(2) FA authorization, which is required for works that will result in
Harmful Alteration, Destruction or Disruption of fish habitat (HADD). However, the DFO
framework to assess the HADD will follow the Policy for the Management of Fish Habitat (DFO
1986) and employ the Habitat Alteration Assessment Tool (HAAT) that is currently in use by
DFO for projects of large magnitude and is described by a series of habitat model research and
development papers that were prepared by DFO scientists (Minns et al. 1995, 2001; Minns
1997). The HAAT is a model that assigns productivity values, based on substrates, bathymetry
and other habitat parameters on an area basis, to affected fish habitat and also to the proposed
fish habitat compensation works that are intended to offset any losses. OPG and consultants are
currently in discussion with DFO and other stakeholders concerning fish habitat losses and
credible compensation options have been identified.
The assessment must be prefaced with a detailed description of the design, engineering, public
safety and nuclear safety constraints and considerations that led to the proposed design and made
the in-water works an unavoidable part of the Project. The habitat VECs are described as
follows:
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Darlington Creek and Darlington Creek Tributary Habitat – consists of the main branch
of Darlington Creek that crosses the northeast corner of the site and continues east of the
site boundary to where it joins Lake Ontario. Darlington Creek is a permanent fish habitat
with resident fish and invertebrate species and also a migratory community that accesses
the creek seasonally from Lake Ontario. Tributary habitat consists of the intermittent
watercourses that drain eastward from the site across the east site boundary to meet the
main branch of Darlington Creek. One tributary is located north of the CN rail line, in the
proposed soil disposal area. The other tributary is located south of the CN rail line, within
the proposed NND station site footprint. The portions of the intermittent tributaries on the
DN site do not possess the types of habitat that directly support fish or aquatic
invertebrates, but flow from the tributaries contributes to aquatic habitats downstream.
They would therefore be considered “indirect” or “contributing” fish habitat by DFO.
The indicator species and selected for this VEC is white sucker, described below.
Lake Ontario Nearshore Habitat – consists of the shallow areas of Lake Ontario adjacent
to the site and along the north shore, extending out to approximately 30 meters depth.
The Lake Ontario nearshore is an important habitat for many fish species, including
warmwater fish that venture out of bays, marshes and tributaries when nearshore water
temperatures are favourable, and also coldwater fish that move inshore from the open
lake to feed, spawn on shoals or run up tributaries to spawn. The nearshore is a dynamic
environment that produces attached algae, benthic invertebrates, phytoplankton and
zooplankton. The ten indicator species and groups selected for this VEC are the same as
those selected for the aquatic biota VECs and are described below.
1.3.2 Aquatic Biota VECs (Forage Species, Benthivorous Fish and Predatory Fish)
Species or groups of species were chosen as suitable indicators of habitat change. Selection of
indicator species provides for use of specific measures to assess habitat change by focusing the
assessment on receptors with known affinity to the nearshore, history of interaction with nuclear
generating facilities such as DNGS, or particular conservation concern. The Project will interact
with various species in accordance with characteristics such as habitat preferences,
ecological/foraging niche, migratory behaviour, and location of critical habitats (e.g., spawning
and nursery areas). There are many species in Lake Ontario, so the VEC indicator species were
considered according to general trophic web groupings, namely the VECs: forage species,
bottom-feeding or benthivorous species and fish-eating predators or piscivorous species. This
approach was considered less confusing and arbitrary than trying to define “resident” and
“migratory” groups of species from which to choose VEC indicator species, since both use
nearshore habitats and migrate to varying degrees. Further, the trophic approach is relevant to the
ERA which is being conducting as part of the EA and considers the uptake and transfer of
contaminants among trophic levels. The VEC indicator species are described below.
Benthic Invertebrates – comprise a community of species including aquatic worms,
insects, crustaceans, snails and mussels that live within or on top of the lake bed
substrates. Benthic invertebrates are important food items for many fish species and for
wildlife such as diving ducks, which forage directly in benthic habitats and bank
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swallows, which forage indirectly on benthos in the form of flying adult insects that
develop from benthic larvae;
Round goby – is an exotic invasive fish species that has spread throughout much of the
Great Lakes and has become an important prey species in the Lower Great Lakes. The
round goby is resident in nearshore Lake Ontario habitats, and is one of the dominant fish
species at DNGS based on 2009 surveys;
Emerald shiner – is an abundant schooling minnow that is native to the Great Lakes, and
frequents the nearshore for spawning and feeding. It is an important forage species;
Alewife – is a schooling member of the herring family that was introduced to the Great
Lakes. Alewife are highly migratory and range throughout the entire lake. A single
alewife population occupies Lake Ontario and this species remains the most numerous
and important forage fish despite recent declines related to changes in the Lake Ontario
food web. The alewife moves inshore in the summer to spawn. It is also the dominant
species impinged at DNGS, and along with round goby, one of the dominant species
collected based on 2009 gillnetting surveys;
White sucker – is a bottom-dwelling native fish that feeds on benthic invertebrates and is
resident as adult fish in the nearshore of Lake Ontario. White sucker ascend tributary
streams to spawn, such as Darlington Creek. Adults return to the lake after spawning.
Eggs, larvae and early life stages of white sucker remain in the spawning streams before
returning to the lake;
Round whitefish – is a bottom-dwelling native coldwater fish that moves inshore to feed
and spawn when nearshore waters cool in October and November. Round whitefish
include the nearshore in their foraging ranges during the fall, winter and early spring
when water temperatures are low. Round whitefish eggs remain in nearshore substrates
over the winter and hatch in the spring, after which the young-of-the-year (YOY) fish
begin feeding in the nearshore and gradually move offshore as they grow;
Lake sturgeon – is a bottom-dwelling native benthivorous fish that was once very
common and abundant in the Great Lakes but was decimated by overfishing and habitat
destruction. A long-lived and slow-maturing species, it has shown recent signs of limited
recovery with the appearance of greater numbers of juvenile sturgeon in nearshore areas,
including the areas near the DN site. Recovery of the lake sturgeon population is a
conservation objective shared by Canadian and American agencies;
American eel – is a bottom-dwelling native predator that was encountered frequently
during a study of nearshore habitat at the DN site (Tarandus 1998). American eel has
become the focus of conservation concern in recent years as this once-abundant fish has
declined substantially across much of its range. Habitat in the vicinity of the DN site
represents foraging areas for adult eels;
Lake trout – is a bottom-oriented predatory salmonid. The original Lake Ontario stock of
this species was extirpated and the existing lake trout population is the result of stocking
of hatchery-reared fish derived from Georgian Bay / Lake Huron stocks. Lake trout
reproduction in the lake remains low, and stocking continues to support the current
population. As coldwater migratory fish, lake trout spend much of the year offshore.
Tagging studies have shown that individual fish migrate extensively throughout the lake.
Lake trout move inshore to spawn and feed when nearshore water temperatures are low in
the fall and early winter. Lake trout forage in the nearshore in fall, winter and early spring
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when water temperatures are low. Lake trout eggs overwinter on nearshore shoals and
juvenile trout begin life in the nearshore prior to moving into deeper waters; and,
Salmonid sport fish – comprise several species of introduced trout and salmon that are the
focus of recreational or sport fishing and that are maintained partially or in large measure
by stocking. These species are migratory open-water fish that forage in Lake Ontario but
ascend tributary streams to spawn. These include brown and rainbow trout and coho and
chinook salmon. Atlantic salmon, the original Lake Ontario stock of which was
extirpated by overfishing and damming of spawning tributaries, is the subject of repeated
reintroduction efforts using stocked fish, but has not flourished to date. Lake trout could
be included in this VEC category, but are treated separately because they are not a
favoured species of sport fisherman on the Lake Ontario north shore and because they
spawn in the nearshore and therefore have the potential to interact with the Project in the
context of spawning and recruitment success.
VECs and the indicator species are discussed in the following sections in relation to those Project
works and activities with which they are likely to interact.
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2. EFFECTS ASSESSMENT METHODOLOGY
At the time of completing this TSD, three vendors were being considered by the Province of
Ontario for supplying and installing the reactors and associated equipment for the Project.
Accordingly, the specific reactor to be constructed and operated had not yet been determined.
Therefore, for purposes of the EA, the Project was defined in a manner that effectively
incorporated the salient aspects of all of the considered reactors. Similarly, the existing
environmental conditions and the likely environmental effects of the Project were also
determined in a manner that considered the range of reactor types and number of units that may
comprise the Project.
The essential aspect of the method adopted for defining the “Project for EA Purposes” is the use
of a bounding framework that brackets the variables to be assessed. This bounding framework is
defined within a Plant Parameter Envelope (PPE). The PPE is a set of design parameters that
delimit key features of the Project. The bounding nature of the PPE allows for appropriate
identification of a range of variables within a project for the purpose of the environmental
assessment while also recognizing the unique features of each design. For further information
concerning the use of the PPE for this EA, the reader is directed to Section 2.1 of the EIS.
The information presented in this TSD is deemed to be appropriately bounding so as to facilitate
the assessment of environmental effects that may be associated with any of the considered
reactors. As both the EA studies and the vendor selection programs continue, it may be that
aspects of this TSD are updated to respond to these evolving programs, in which case the
updated information will be presented in an addendum to this TSD or in the EIS. The EIS itself
will remain subject to edits until it has been accepted by the JRP as suitable for the basis of the
public hearing that will be convened to consider the Project.
This TSD is a document prepared in support of the EIS. Where there may be differences in the
information presented in the two documents, the EIS will take precedence for the reasons noted
above.
2.1 Assessment Framework
Details of the EA process and the assessment methods used throughout the EA are described in
Chapter 3 of the Environmental Impact Statement (EIS). This TSD focuses specifically on the
assessment of effects of the Project on the environment and in doing so the following procedural
steps were applied:
Detailed screening for potential Project-environment interactions;
Identification of likely changes to the environment;
Identification and assessment of likely effects on the environment as a result of changes;
and,
Consideration of mitigation measures and determination of likely residual effects.
These steps are further described in Section 2.3.
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2.2 Assessment Basis, Spatial Boundaries, Methods and Criteria
2.2.1 Project Basis for the Assessment
A full description of the Project that is the subject of the EA is provided in the Scope of the
Project for EA Purposes TSD. A summary description of the specific works and activities that
collectively comprise the Project (i.e., Basis for the EA) is included in this TSD as Appendix A.
The Scope of the Project for EA Purposes TSD described four development scenarios and three
reactor operation scenarios. For the purpose of screening and assessment of Project interactions
with the AE, bounding scenarios were chosen for the Site Preparation and Construction Phase
and for the Operation and Maintenance Phase.
For the Site Preparation and Construction Phase, Site Development Scenario 1, Four ACR 1000
Reactors with Once-Through Cooling, was chosen as the bounding scenario as it would
encompass the maximum extent of in-water works that would affect aquatic habitat and aquatic
biota, including:
Bridge crossing (box culvert) of the main branch of Darlington Creek for heavy
construction equipment access;
Loss of Treefrog, Polliwog and Dragonfly ponds;
Alterations to site drainage, reuslting in the loss of portions of intermittent tributaries to
Darlington Creek;
Alteration/disruption of Coot’s Pond;
Realignment and possible loss of upper portions of an intermittent tributary to Lake
Ontario near Coot’s Pond;
Lake infill totalling approximately 40 hectares along approximately 2 kilometers of
shoreline in front of the DNGS and NND sites, including loss of habitat and alteration of
coastal processes;
Blasting and excavation in an area of approximately 1.1 hectares, as defined in the SWE -
Environmental Effects Assessment TSD required to construct the porous veneer once-
through Condenser Circulating Water (CCW) intake structure in an area approximately
100 meters across in at least 10 meters water depth approximately 850 meters offshore;
and,
Blasting and excavation required to install approximately 90 diffuser ports (cumulative
area of approximately 0.7 hectares) for the once-through CCW discharge structure on the
discharge tunnel along an alignment extending from approximately 870 m to 1,850 m
offshore, in 10-20 meters water depth.
For the Operation and Maintenance Phase, Reactor Operations Scenario 1, Four ACR-1000
Reactors, was chosen as the bounding scenario as it involves the once-through cooling water
system (approximately 230 m3/s) and service water requirements (approximately 20 m
3/s) which
involves a slightly higher rate of once-through CCW circulation than the other scenarios, based
on information provided in the Technical Support Document – Scope of the Project for EA
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Purposes. The rate of once-through cooling water circulation is an important factor in the
assessment of the following key interactions:
Impingement and entrainment of aquatic organisms, particularly fish (adults, juvenile,
eggs and larvae); and
Thermal effects on habitat suitability and aquatic organisms.
For the purpose of the assessment, the bounding once-through CCW flow was assumed to be
250 m3/s, consistent with the SWE - Environmental Effects Assessment TSD. The intake
structure design was assumed to be a scaled-up version of the DNGS lakebottom porous veneer
intake as described in the SWE - Environmental Effects Assessment TSD. This design is expected
to achieve a mean water intake velocity (as permitted at DNGS) of less than 0.15 m/s at a
distance of 5 cm above the intake structure. Consistent with the SWE Effects Assessment, the
rate of circulation was assumed to maintain a maximum change in water temperature between
intake and discharge of 9oC and the resulting size and temperature characteristics of the
discharge mixing zone were considered as predicted by the SWE thermal plume model. An
alternative cooling scenario involving increased discharge water temperature of 15.6oC above
ambient was addressed in SWE - Environmental Effects Assessment TSD. SWE concluded that
although the discharge temperature would be higher, the combination of reduced flow
requirements and the function of the discharge diffuser would result in a similar mixing zone
area and similar temperature conditions to the 9oC option. Although higher temperatures would
occur at the diffuser ports, the mixing is expected to occur rapidly and over a short distance. The
discharge velocity and turbulence along the diffuser line makes it unlikely that aquatic organisms
would frequent the area or remain immediately in front of diffuser ports. As such, the 9oC
scenario was used as the basis of the assessment.
The cooling tower option requires intake of makeup and service water of only approximately
6 m3/s, compared with the 250 m
3/s once-through cooling flow. Although a porous-veneer intake
is not anticipated for the cooling tower intake, it will nevertheless include in-design mitigation
measures to limit fish losses. The cooling tower discharge structure will incorporate a (single-
port) diffuser to facilitate mixing. As such, the potential environmental effects of impingement
and entrainment, and thermal discharge, associated with the cooling tower option are considered
to be fully addressed within the once-through cooling bounding scenario.
2.2.2 Spatial Boundaries for the Assessment
Generic spatial boundaries (i.e., study areas) applied for the EA are described in the EIS in a
context of Site Study Area (SSA), Local Study Area (LSA) and Regional Study Area (RSA).
These generic study areas were considered for their specific relevance to the AE and modified as
appropriate to recognize the unique nature of this environmental component. The study areas
applied for this assessment, including the rationale for their delineation, are described below and
are illustrated in Figures 2.2-1, 2.2-2 and 2.2-3. Sampling locations for specific 2008 and 2009
studies involving fish habitat assessment of the proposed infill area, larval fish and adul fish
community studies and Darlington Creek habitat assessment are documented in the AE Existing
Environmental Conditions TSD.
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Site Study Area (SSA): the property, including land and portions of Lake Ontario, on
which the project is located and which is under the care and control of OPG; plus those
adjacent areas that are clearly associated with it as a result of biophysical connection (see
Figure 2.2-1);
Local Study Area (LSA): land and portions of Lake Ontario beyond the SSA where
there is a reasonable potential for obvious, readily-understood and mitigable
environmental effects related to the Project (see Figure 2.2-2); and,
Regional Study Area (RSA): land and portions of Lake Ontario beyond the LSA that
could reasonably be considered relevant in the assessment of more wide-spread
environmental effects, and wherein there is a potential for cumulative and socio-
economic effects related to the Project. The RSA is identical to the SWE RSA (see
Figure 2.2-3).
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2.2.3 Analytical Methods for the Assessment
Assessment of effects across a wide range of environmental components and sub-components
requires the use of a variety of different analytical methods (e.g., computer models, manual
calculations, relevant project experiences, formal case studies, comparison against relevant
benchmarks, professional judgement). The specific methods used in the assessment of
environmental effects in the AE are as follows:
Site Preparation and Construction Phase activities will result in “Harmful Alteration,
Disruption or Destruction of Fish Habitat” (HADD) as defined by the section 35(2) of the
FA. The method of assessment related to this effect considered both the extent and
qualitative character of the affected habitats, including the role and importance of
affected habitats in the context of the Canadian fishery and the mitigation and
compensation strategies that will be required, in anticipation of the need for an
authorization under section 35(2) of the FA.
Site Preparation and Construction Phase development of the watercourse crossing at
Darlington Creek was assessed as similar to existing road crossings that used box culverts
and associated in-stream disturbance. The assessment also considered the DFO
Operational Statement for clear-span bridges (DFO 2007), and noted that construction of
a two-lane clear span crossing could avoid a HADD and the need for a section 35(2) FA
authorization.
Site Preparation and Construction Phase blasting activities required to complete the CCW
intake and discharge structures were assessed in consideration of the DFO “Guideline for
the Use of Explosives In or Near Canadian Fisheries Waters” (Wright and Hopky, 1998)
approach to design, mitigation and assessment in anticipation of necessity of an
authorization under section 32 of the FA.
Operation and Maintenance Phase once-through CCW fish impingement and entrainment
(I&E) losses were assessed using results of DNGS impingement and entrainment studies
as an applicable case study that is expected to approximate these effects at the NND.
DNGS is a relevant surrogate case as it shares the site with the Project and the Project
bounding scenario assumes a similar intake structure. In addition, recently collected
DNGS impingement and entrainment data was used to estimate losses that could be
associated with the NND. The cooling tower option was also assessed to determine I&E
losses that could be associated with the intake of make-up cooling and service water.
Operation and Maintenance Phase once-through CCW thermal discharge effects were
assessed by numerical modelling of the dispersal of heated water within Lake Ontario by
the SWE component. DNGS was adopted as a case study for the predicition of
anticipated thermal effects. DNGS is a relevant surrogate case as it shares the site with
the Project and the Project bounding scenario (once-through cooling) will employ a
similar diffuser structure with similar performance characteristics. The cooling tower
option thermal discharge was also assessed by SWE on the assumption that a single-port
diffuser would be installed to enhance mixing of heated water with ambient lake water.
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2.2.4 Criteria for the Assessment
The assessment of Project-related effects requires criteria that are relevant to protection and
conservation of various environmental components. For effects that relate to changes in aquatic
habitat, the area of habitat affected and the qualitative function of the habitat constitute the
criteria of assessment. These criteria, which can be summarized as habitat area and habitat
quality, are consistent with the approach to seeking authorization under section 35(2) of the FA.
For effects that relate to various aquatic species the criterion of assessment is population
conservation. In other words, the effects on biota are assessed for the likelihood of affecting
species at a population level that would be expected to measurably change populations and
possibly affect their viability. The criteria of assessment for the AE are further described in
Section 3.2.
2.3 Process Steps for Determination of Likely Environmental Effects
2.3.1 Detailed Screening for Potential Project-Environment Interactions
A preliminary screening for potential interactions was conducted during baseline characterization
studies to ensure appropriate focus of those studies. A more detailed screening was subsequently
conducted for each component of the environment based on the Description of the Project (as
summarized in the Basis for the EA in Appendix A) to direct the effects assessment effort. The
screening approach allows the EA studies to focus on the aspects of key importance, thus
minimizing assessment effort where there is low potential for Project-related effect.
Each of the relevant Project works and activities was considered individually to determine if
there was a plausible mechanism for the Project to interact with the environment.
2.3.2 Evaluation for Likely Measurable Changes in the Environment
Each potential interaction was evaluated to determine if it would be likely to result in a
“measurable” change to the environment. These changes are summarized in Table 2.3.2-1,
below. For purposes of the EA, a measurable change to the environment is defined as a change
that is real, observable or detectable compared with existing (baseline) conditions. A predicted
change that is trivial, negligible or indistinguishable from background conditions is not
considered to be measurable.
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TABLE 2.3.2-1
Range and Relevance of Potential Change in the AE
Project
Phase/Activity
Effect and
Environmental
Subcomponent
Assessment
CriteriaRange and Relevance of Potential Change
Site Preparation and
Construction –
Mobilization and
Preparatory Works
(Site Clearing),
Excavation and
Grading,
Management of
Stormwater
Loss/alteration of
ponds, creeks and
intermittent
tributaries
Habitat and biotic
community
quality and extent
(area or length)
Primary effects limited to SSA and are considered
low due to scope of restoration. Indirect effects to
LSA or RSA are considered low due to scope for
on-site restoration and limited connectivity of on-
site aquatic habitats to Lake Ontario or adjacent
watersheds.
Site Preparation and
Construction –
Marine and
Shoreline Works
(Lake infill and
Shoreline
Stabilization),
Management of
Stormwater
Loss/alteration of
nearshore Lake
Ontario habitat
Direct loss of fish
and invertebrates
Habitat extent
and function
relevant to Lake
Ontario aquatic
biota populations
Likelihood of
losses to affect
fish populations
Direct effects limited to SSA, with low potential for
population-level effects on LSA and RSA level due
to small proportion affected of available similar
habitat.
Direct loss of fish and invertebrates limited to the
SSA and mitigated by fish salvage where
practicable.
Site Preparation and
Construction –
Intake and Diffuser
Loss/alteration of
nearshore Lake
Ontario habitat
Direct loss of fish
and invertebrates
Habitat extent
and function
relevant to Lake
Ontario aquatic
biota populations
Likelihood of
losses to affect
fish populations
Direct effects limited to SSA, with low potential for
population-level effects on LSA and RSA due to
small proportion affected of available similar
habitat.
Direct blasting effects limited to small proportion of
SSA with low fish density and therefore low
likelihood of mortality that could affect
populations.
Operation and
Maintenance –
Operation of
Condenser
Circulating Water,
Service Water and
Cooling Systems -
Intake Cooling
Water
Fish
impingement
(eggs, larvae)
Likelihood of
losses to affect
fish populations
Direct effects limited to fish within the SSA. LSA
and RSA effects possible due to fish migration, but
considered low due to effective mitigation provided
by intake placement and design.
Fish and
invertebrate
entrainment
Likelihood of
losses to affect
fish, invertebrate
and plankton
populations
Direct effects limited to fish, invertebrates and
plankton within the SSA. Effects may extend to
LSA and RSA due to migration and transport of
biota by currents, but considered low due to
mitigation provided by intake placement and
design, low susceptibility of benthos, as well as low
proportion of plankton population entrained and
population-level compensatory mechanisms of fast-
reproducing plankton.
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Project
Phase/Activity
Effect and
Environmental
Subcomponent
Assessment
CriteriaRange and Relevance of Potential Change
Operation and
Maintenance –
Operation of
Condenser
Circulating Water,
Service Water and
Cooling Systems -
Discharge Thermal
Effluent
Thermal effects
on nearshore
habitat suitability
and fish species
Extent and
behaviour of
thermal plume
(modelling by
SWE component)
in relation to
preferred,
Maximum
Weekly Average
Temperature
(MWAT),
Weekly Hourly
Maximum
Temperature
(WHMT) and
lethal
temperatures
Direct effects limited to diffuser area in SSA and
extent of thermal plume in SSA and LSA. Low
potential for indirect population-level effects in
RSA due to mitigation of unnatural thermal
conditions by the diffuser. Relevance of thermal
conditions based on preferred temperature ranges of
nearshore and pelagic fish species, MWATs,
WMHT, and lethal temperatures as applicable, in
context of net effect on populations.
2.3.3 Assessment of Likely Effects on the Environment
Each Project interaction likely to result in a measurable change to the environment was further
evaluated to identify the likely effect of the change on a Valued Ecosystem Component (VEC)
selected for the AE, or on a pathway to other environmental components. VECs relevant to the
AE are described in the AE - Existing Environmental Conditions TSD.
Each likely effect was identified and described as either beneficial or adverse. Where the likely
effect was determined to be beneficial, no further assessment was conducted. Similarly, where
the likely effect was determined to be adverse, but clearly not of concern, no further assessment
was conducted. Rationale was provided in each case where further assessment was not
considered to be warranted. All other likely adverse environmental effects were carried forward
for consideration of mitigation opportunities.
2.3.4 Consideration of Mitigation and Determination of Likely Residual Effects
For each likely adverse effect (other than those clearly of no concern), possible means that were
technically and economically feasible were identified and considered for mitigating (i.e.,
eliminating, reducing or controlling) the effect. Each likely adverse effect was re-evaluated
assuming implementation of the identified mitigation measures, to determine the residual effect
that would remain after mitigation.
By advancing through the assessment in the methodical manner described above, the wider range
of potential Project-environment interactions identified at the beginning of the process was
progressively screened and evaluated to result in a narrower range of residual adverse effects
identified as likely at the end of the process. This progression from potential interactions
through to likely residual adverse effects is an important aspect of the overall assessment
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methodology used, especially as it relates to the subsequent determination of significance of the
likely residual adverse effects.
Data has been summarized in the AE Existing Conditions TSD. Summary statistics used in this
report depend on a number of factors including but not limited to:
Regulatory requirements;
Precedence;
Professional judgment;
The creation of bounding scenarios or conservatism;
Use by and consistency with another environmental component; and/or,
Use in ongoing baseline monitoring.
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3. ASSESSMENT AND MITIGATION OF ENVIRONMENTAL EFFECTS
This section of the TSD describes the assessment conducted to determine the likely adverse
effects of the Project on the environment, and more specifically, on the VECs selected as
features of the AE to be the focus of the EA. The process followed in carrying out the
assessment is described in Chapter 2.
An evaluation of the significance of the residual adverse effects of the Project on the
Environment is presented collectively for all likely environmental effects in all relevant
environmental components, in the EIS.
3.1 Detailed Screening for Potential Project-Environment Interactions
Each Project work and activity (see Appendix A) was screened to consider if there was a
plausible mechanism or pathway by which it could interact with the AE. The screening
decisions were based on existing site information, knowledge of the environmental interaactions
at DNGS and other facilities, and the experience and professional judgment of the EA
biologists. Where no pathways were identified to the AE for a particular work or activitiy, these
were not considered further in the evaluation of effects on the AE. The results of the AE
screening and the rationale associated with each work and activity are summarized in
Table 3.1-1, below.
The Aquatic Environment comprises two environmental sub-components: Aquatic Habitat and
Aquatic Biota. The assessment addressed two primary effects (i.e., direct) pathways;
specifically, physical changes to aquatic habitat, and organism-level effects involving intake
losses and thermal discharge. Potential effects on non-human biota, including in the Aquatic
Environment, as a result of exposures to radiological and conventional constituents from NND
are evaluated in the Ecological Risk Assessment and Assessment of Effects on Non-Human
Biota TSD. Potential effects on water quality are briefly addressed in this document for
clarification purposes and expanded upon in the SWE - Assessment of Environmental Effects
TSD.
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TABLE 3.1-1
Potential Project-Environment Interactions in the AE
AE
Project Works and Activities
Ha
bit
at
Bio
ta
Rationale
SITE PREPARATION AND CONSTRUCTION PHASE
Mobilization and Preparatory Works
Clearing and grubbing will remove on-site ponds and approximately 400-meters of the
uppermost portions of two intermittent tributaries to Darlington Creek located on the east
side of the site.
Construction access road will cross Darlington Creek.
Interactions with the AE may occur through erosion and sedimentation (i.e., that directly
interact with the Surface Water environment). The potential interactions from this Project
Work and Activity and the Surface Water Environment and thus potential interactions with
the Aquatic Environment are captured in the Management of Stormwater Activity.
Excavation and Grading
Coot’s Pond may be altered or disrupted, with site restoration to follow.
Upper reaches of a Lake Ontario intermittent tributary near Coot’s Pond may be realigned
and/or reduced.
Interactions with the AE may occur through erosion and sedimentation (i.e., that directly
interact with the Surface Water environment). The potential interactions from this Project
Work and Activity and the Surface Water Environment and thus potential interactions with
the Aquatic Environment are captured in the Management of Stormwater Activity.
Areas dependent on groundwater discharge to the east of the site (i.e., Darlington Creek), if
present, will be minimally affected by the dewatering of the site
Marine and Shoreline Works
40 hectare lake infill, including construction of the wharf.
Blasting and excavation of intake (1.1 hectares) and diffuser (0.7 hectare) structures could
result in incidental mortality of fish and invertebrates.
Development of Administration and
Physical Support Facilities
Interactions with the AE may occur through erosion and sedimentation. The potential
interactions from this Project Work and Activity and the Surface Water Environment and
thus potential interactions with the Aquatic Environment are captured in the Management
of Stormwater Activity.
Construction of the Power Block
Interactions with the AE may occur through erosion and sedimentation. The potential
interactions from this Project Work and Activity and the Surface Water Environment and
thus potential interactions with the Aquatic Environment are captured in the Management
of Stormwater Activity.
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AE
Project Works and Activities
Ha
bit
at
Bio
ta
Rationale
Construction of Intake and Discharge
Structures
Blasting and excavation of intake (1.1 hectares) and diffuser (0.7 hectare) structures could
result in the loss of a small area of potential fish habitat in the footprints of both the intake
and discharge structures.
Underwater blasting would result in incidental mortality of fish and invertebrates (in
localized area).
Construction of Ancillary Facilities
Interactions with the AE may occur through erosion and sedimentation. The potential
interactions from this Project Work and Activity and the Surface Water Environment and
thus potential interactions with the Aquatic Environment are captured in the Management
of Stormwater Activity.
Construction of Radioactive Waste
Storage Facilities
Interactions with the AE may occur through erosion and sedimentation. The potential
interactions from this Project Work and Activity and the Surface Water Environment and
thus potential interactions with the Aquatic Environment are captured in the Management
of Stormwater Activity.
Management of Stormwater
As the site is developed, ditches and swales will be constructed to collect and convey
surface water to stormwater management ponds and ultimately discharge to an existing
drainage course or Lake Ontario.
Potential beneficial effect of stormwater management facilities once design modifications
are implemented.
Supply of Construction Equipment
and Material and Plant Operating
Components
Interactions with the AE may occur through erosion and sedimentation. The potential
interactions from this Project Work and Activity and the Surface Water Environment and
thus potential interactions with the Aquatic Environment are captured in the Management
of Stormwater Activity.
Management of Construction Waste,
Hazardous Materials, and Fuels and
Lubricants
No direct pathway to AE.
No plausible interaction as secondary containment of storage tanks (e.g., fuel oil) will be
provided to contain any releases from spillage or tank rupture.
This activity does not include the disposal of excavated soil (see Excavation and
Grading).
Workforce, Payroll and Purchasing No direct pathway to AE.
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AE
Project Works and Activities
Ha
bit
at
Bio
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Rationale
OPERATION AND MAINTENANCE PHASE
Operation of Reactor Core
No direct pathway to the AE. Under normal operating conditions, the operation of the
reactor core does not directly interact with any subcomponent of the Surface Water
Environment, and thus does not interact with any subcomponent of the Aquatic
Environment.
Operation of Primary Heat Transport
System No direct pathway to the AE.
Operation of Active Ventilation and
Radioactive Liquid Waste
Management Systems
No direct pathway to the AE.
Operation of Safety and Related
Systems No direct pathway to the AE.
Operation of Fuel and Fuel Handling
Systems No direct pathway to the AE.
Operation of Secondary Heat
Transport System and Turbine
Generators
No direct pathway to the AE.
Intermittent releases of Steam Generator blowdown will be tested and treated if necessary
to comply with the appropriate criteria for surface water discharge to Lake Ontario.
Operation of Condenser Circulating
Water, Service Water and Cooling
Systems
Impingement and entrainment of aquatic organisms.
Thermal effects on aquatic habitat and aquatic organisms through discharge of cooling
water.
Operation of Electrical Power
Systems No direct pathway to the AE.
Operation of Site Services and
UtilitiesNo direct pathway to the AE.
Management of Operational Low and
Intermediate-Level Waste No direct pathway to the AE.
Transportation of Operational Low
and Intermediate-Level Waste to a
Licensed Off-site Facility
No direct pathway to the AE.
Dry Storage of Used Fuel No direct pathway to the AE.
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AE
Project Works and Activities
Ha
bit
at
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Rationale
Management of Conventional Waste
No direct pathway to the AE. No plausible interaction as non-hazardous and non-
radioactive liquid wastes will be controlled in accordance with provincial waste
management regulations and provincial C of A requirements respectively.
Replacement / Maintenance of Major
Components and Systems
Potential direct pathway to the AE. There would likely be a reduction in the number of
fish impinged/entrained with reduced flows during a major refurbishment. However, once
the refurbishment is complete, impingement and entrainment would likely return to
previous levels. Other interactions with aquatic habitat and biota unlikely as the effects on
subcomponents of the SWE (namely water temperature and water quality) are not
expected. If refurbishment or maintenance activities result in the shutdown of one or
more reactors, the liquid effluents from these systems will be treated sufficiently as per
applicable legislation (e.g., C of A, MISA).
Physical Presence of the Station The Physical Presence of the Station is not considered to have the potential to interact
with the AE.
Administration, Purchasing and
Payroll No direct pathway to the AE.
Note:
A dot ( ) in the table grid indicates a potential Project-Environment interaction.
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3.2 Evaluation for Likely Change to the Environment
Each work and activity identified above in Table 3.1-1 as potentially interacting with the
environment was further evaluated to determine if it would be likely to result in a measurable
change to the sub-components of the AE. The evaluation considered the professional judgement
of the assessment team and quantifiable evaluation criteria as appropriate.
The criteria applied within the AE for evaluation of likely change in the environment (as well as
for the subsequent assessment of effects of any changes) are described in Table 3.2-1.
With respect to aquatic habitat, evaluation criteria are habitat quantity and quality, which
integrate aspects of habitat productivity. These parameters will be important to agency
stakeholders, such as DFO, and will guide the development of mitigation measures and fish
habitat compensation. DFO’s approach to the assessment, of the lake infill area in particular, will
require the use of the HAAT, which models and estimates the balance of fish productivity loss or
gain and can guide the design of appropriate mitigation and compensation scenarios.
For aquatic biota, the assessment focused on whether the various species populations that
comprise the aquatic biological community will be measurably affected. Effects on biota were
evaluated based on an understanding of pathways of likely interaction that can act on individual
organisms with the Project. However the ultimate measure and significance of these interactions
rests at the population level.
TABLE 3.2-1
Evaluation Criteria used in the AE
Sub-Component (AE) Evaluation Criteria or Parameter
Aquatic Habitat Quantity (i.e., area) and quality (i.e., function and relative
productivity with respect to aquatic community).
Aquatic Biota Population conservation (i.e., impingement losses in the
context of known or likely population size of VEC indicator
species).
The works and activities with potential to interact with the AE were evaluated, as described
below, to determine if the interaction was likely to result in a measurable change to the sub-
components of the AE. Those works and activities for which there is an identified surface water
and/or air quality pathway to the AE, but that will be addressed primarily by other technical
disciplines were not directly assessed here. It was expected that any residual effects of those
pathways would be assessed against criteria relevant to those disciplines and, due to a
combination of effects management features and any necessary additional mitigation measures,
would not result in measurable change to aquatic habitat or populations of aquatic organisms.
The potential environmental impacts were assessed considering different categories, levels and
criteria. The definitions and levels for the different categories are presented below:
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Direction: The direction of an impact may be positive, neutral or negative with respect to a
given issue (e.g., enhancement of aquatic habitat would be classed as a positive direction,
whereas habitat loss or fragmentation would be considered a negative direction).
Extent: The spatial area affected by the project. For the purposes of this assessment Extentwas classified as: within the SSA, the LSA or the RSA.
Magnitude: This describes the amount of change in a measurable parameter or the
predicted/actual level of change relative to an existing or specified condition. Magnitude was
defined according to the specific nature of the impact. For the purpose of this assessment,
magnitudes were classified as: negligible, low, moderate and high.
Duration: This refers to the length of time over which an environmental impact occurs. For
the purpose of this assessment, duration was classified as: low (i.e., lasting only during the
Site Preparation and Construction Phase), moderate (i.e., lasting the entire Operation and
Maintenance Phase) and high (i.e., extending beyond the closure of the project, sometimes in
perpetuity).
Reversibility: This is an indicator of the potential for recovery of a given receptor from the
impact. For the purpose of this assessment, reversibility was classified as high for impacts
that reversible immediately after the source of the impact is removed, moderate for impacts
that reverse in the short term, low for impacts that are reversible in the long term only or are
irreversible.
3.2.1 Site Preparation and Construction Phase
3.2.1.1 Mobilization and Preparatory Work and Excavation and Grading
Darlington Creek Road Crossing
The construction of the access road may include a crossing of Darlington Creek at the northeast
corner of the DN site. The crossing is assumed to be a box culvert similar to existing crossings of
the creek at the South Service Road and Highway 401. The construction of the box culvert could
result in local habitat destruction, and would constitute a HADD under section 35(2) of the FA.
As such the Darlington Creek road crossing was advanced for assessment.
Removal of On-Site Ponds
Development of a soil disposal area north of the CN rail line will require removal of Treefrog,
Dragonfly and Polliwog Ponds at the clearing and grubbing stage. The ponds were constructed
in a natural depression as part of OPG’s biodiversity program at the DN site. As the ponds
represent a measurable proportion of on-site aquatic habitat, their loss was advanced for
assessment.
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Removal of Upper Reaches of Intermittent Tributaries to Darlington Creek
Excavation south of the CN rail line will be required to construct the station and ancillary
facilities. Much of the excavated material will be deposited as a large mound north of the CN rail
line. Each of these areas contains about 400 meters of intermittent swale that drains into
Darlington Creek. These features will be lost at the clearing and grubbing stage. In the soil
disposal area, it may be possible to restore similar habitat as part of drainage and stormwater
management and maintain the connection to Darlington Creek. In the area of the NND station,
grades will be altered so much that the drainage from the former swale catchment will be
diverted to Lake Ontario instead of Darlington Creek. It may be possible to create a swale to
offset the loss of the existing feature, but the connection to Darlington Creek will be lost. As a
measurable reduction of “indirect” or “contributing” fish habitat could occur, removal of the
upper reaches of the intermittent tributaries was advanced for assessment.
Areas dependent on groundwater discharge to the east of the site (i.e., Darlington Creek), if
present, will be minimally affected by the dewatering of the site. It is estimated that between
5-7% of the total Creek volume would be reduced as a result of dewatering activities (see
Geological and Hydrogeological Environment Assessment of Environmental Effects TSD).
However, this is not expected to have a significant impact on the Darlington Creek fisheries.
Alteration/Disruption of Coot’s Pond
Project use of the existing construction waste landfill could change the shape and extent of its
footprint. Coot’s Pond will be avoided to the extent possible, but there could be minor alteration
or temporary disruption of portions of the pond. Affected areas of the pond will be restored
following the Site Preparation and Construction Phase. As changes to Coot’s Pond could affect a
measurable portion of on-site aquatic habitat, even temporarily, this effect was advanced for
assessment.
Alteration of Upper Reaches of an Intermittent Lake Ontario Tributary
Project use of the existing construction waste landfill could change the shape and extent of its
footprint, with possible effects on the intermittent watercourse that lies along the east boundary
of the landfill and south of Coot’s Pond. Realignment of portions of the tributary may be
required to allow changes to the extent of the landfill. Marginal upper portions may be filled. As
changes to the watercourse could result in a loss of indirect or contributing fish habitat, this
effect was advanced for assessment.
3.2.1.2 Marine and Shoreline Works - Lake Infill
Preparation of the Project site and expansion of the security perimeter setback from Lake Ontario
in front of DNGS will involve the filling and loss of approximately 40 hectares of nearshore
habitat along approximately 2 kilometers of shoreline, with potential to alter nearshore coastal
processes. Since this activity represents a measurable change in the area of nearshore habitat
within the SSA lake infill was advanced for assessment.
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3.2.1.3 Construction of Intake and Discharge Structures
Construction of the intake and discharge tunnels for the once-through condenser cooling water
system is expected to involve boring or blasting through bedrock beneath the lake bed, with little
scope for interaction with the AE due to the separation of the tunnel from habitat within the lake.
However, blasting and excavation to open the intake tunnel to the lake and to prepare the lake
bed for installation of the porous veneer intake structure could involve incidental fish losses and
will replace an area of the lake bed habitat with an artificial structure. Likewise, blasting and
excavation for the installation of diffuser ports along the discharge tunnel could involve limited
fish losses and will result in the loss of natural lake bed habitat at each port. This interaction
would also occur to some degree with a cooling tower scenario, as intake and outfall structures
would still be required. Although these structures would be smaller (with a smaller permanent
footprint), the method of construction would be open trench and laying of pipe rather than
underground boring beneath the lake and could involve similar total area of temporary
disturbance during construction. As such, the construction of intake and discharge structures
was advanced for assessment.
3.2.1.4 Management of Stormwater
As the site is developed, ditches and swales will be constructed to collect and convey surface
water to stormwater management ponds and ultimately discharge to an existing drainage course
or Lake Ontario. Stormwater management features will be developed to address the
requirements for runoff control both during site preparation and construction (temporary), and
during operations (permanent). There is a potential beneficial effect on fish habitat from
stormwater management facilities once design modifications are implemented.
Good Industry Management Practices during all phases of the NND Project will be
implemented with respect to stormwater management. Examples include: sediment control
practices, dewatering water treatment, stormwater conveyance systems (if necessary), and
conventional stormwater treatment methods such as stormwater management ponds and oil-grit
separators. In addition all water having come into contact with blasting agents (e.g., ANFO)
will be collected and appropriately managed and disposed.
This interaction is not forwarded on for further assessment.
3.2.2 Operation and Maintenance Phase
3.2.2.1 Operation of Condenser Circulating Water, Service Water and Cooling Systems
Impingement and Entrainment
Depending on the cooling-water technology that is selected, intake flows could be as high as
250 m3/s for once-through cooling or 6 m
3/s for cooling towers. For once-through cooling, it is
assumed that a lakebottom porous veneer intake structure will be constructed, likely as a scaled-
up version of the existing intake at DNGS. The DNGS intake design has proven very effective in
mitigating fish losses due its offshore location and designed average approach velocity of
<0.15 m/s (0.5 fps). For the cooling tower option, approach velocity reductions, small intake
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diameter as well as siting the intake away from the nearshore environment will be used as
possible mitigation strategies. Despite the focus on in-design mitigation, lake water withdrawal
under either scenario will result in some impingement of adult and juvenile fish and entrainment
of fish eggs, fish larvae and aquatic invertebrates. A study of DNGS I&E losses was conducted
based on the 2006-7 impingement data collected at DNGS and supported by recent entrainment
studies conducted at DNGS (Ager et al., 2005; Ager et al., 2006). The results have been used in
a case study approach to forecast NND I&E losses that could occur. As such, the impingement
and entrainment effects were advanced for assessment. No SARA/ESA species are expected to
be impinged.
Thermal Discharge
At the other end of the cooling-water system lies the discharge, which will also be subject to
intensive in-design mitigation. DNGS is the model and case study selected for assessment of
thermal effects since its discharge diffuser has proven very effective in mitigating the
development of extensive thermal plumes. Nevertheless, discharge of heated lake water as part
of the operation of a once-through condenser cooling water system will result in measurable
changes to water temperature conditions in the vicinity of the discharge diffuser. This effect was
advanced for AE assessment related to aquatic habitat and biota, and has also been assessed as a
physical effect by the SWE component and presented in the corresponding SWE –
Environmental Effects Assessment TSD. SWE assessed two once-through scenarios, representing
discharge of heated water 9oC and 15.6
oC above Lake Ontario ambient temperature, but
concluded that a mixing zone of similar extent would occur due to the compensating factor of
lower system flow associated with the higher temperature option. As such, the bounding scenario
assessment focuses on the more “conventional” 9oC scenario. Discharge of cooling tower
blowdown would involve a much smaller diffuser structure, flow rate and mixing zone, and is
therefore considered to be bounded by the once-through option.
3.3 Assessment of Likely Effects on the Environment
Preceding assessment steps have identified the various works and activities that may potentially
interact with the AE and, if so, result in a measureable change to its sub-components. This
assessment step evaluates likely environmental effects on VECs and indicator species as a result
of those works and activities. As such, the discussion is organized first by Phase or Project
Work and Activity of the Project, and then by likely environmental effect. The criteria used in
determining if a work or activity was likely to lead to measurable environmental change were
also used for the assessment of likely effects. They are described above in Table 3.2-1.
Professional judgement and the experience of the assessment team remained as important
elements of the applied assessment criteria.
3.3.1 Site Preparation and Construction Phase
3.3.1.1 Darlington Creek Crossing
In-stream construction of box culverts would result in the local loss of a short reach of stream
habitat, as well as potential sedimentation in the creek from construction activities, and would be
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considered as a HADD by DFO (section 35(2) of the FA). A recent habitat assessment of
Darlington Creek indicated that the upper reaches (near proposed in-stream construction) were
the best habitat, and supported rainbow trout (Section 3.3 of the AE Existing Conditions TSD).
Habitat loss could be avoided by mitigation measures that include construction of a two-lane
clear-span bridge, which would avoid in-water works permanent loss of creek habitat. This
design would be consistent with the DFO Operational Statement for clear-span bridges (DFO
2007). Employing appropriate setbacks and sediment and erosion controls during construction,
the crossing would avoid HADD. The crossing would not require section 35(2) FA authorization.
Alternatively, stream crossings could be avoided altogether by aligning the access road further to
the west.
Therefore, in summary, with appropriate mitigation measures applied, there would be no effects
on Darlington Creek aquatic habitat.
3.3.1.2 Removal of Upper Reaches of Intermittent Tributaries to Darlington Creek
Two intermittent swales may be removed as part of NND site excavation and soil disposal
(Figure 3.3.1-1). One tributary is located north of the CN rail line, shown in Figure 3.3.1-1 in
drainage area D2, in the proposed soil disposal area. The other tributary is located south of the
CN rail line, shown in Figure 3.3.1-1 in drainage area E, within the proposed NND station site
footprint. Based on observations by Golder biologists, the portions of the intermittent tributaries
on the DN site do not possess the types of habitat that directly support fish or aquatic
invertebrates. However, flow in the tributaries contributes to aquatic habitats downstream and
they would therefore be considered “indirect” or “contributing” fish habitat by DFO.
The north tributary is an intermittent swale within an agricultural field that occupies the DN site
and also extends eastward to Darlington Creek. Golder’s on-site observations confirmed a lack of
aquatic habitat attributes in the on-site portion, aside from the periodic conveyance of runoff.
Agricultural practices on the site include cultivation through the swale and healthy growth of
corn even within the swale, both of which indicated relatively minor flow in this feature despite
heavy summer rainfall during 2008. Approximately 400 meters of the north swale could be lost
or need to be extensively realigned in conjunction with deposition of excess soils in this area.
However, realignment and incorporation of site drainage features into a SWM design for the soil
disposal stockpile is expected to maintain contributions of flow into the lower reaches of the
northern tributary and to Darlington Creek.
The south tributary is an intermittent swale that originates as ditch drainage within a portion of
the former DNGS construction laydown area and extends southeastward through regenerating
former agricultural lands (often called “old field” habitats), hedgerow and reed canary grass
meadow to the eastern property boundary. Approximately 250 meters downstream of the DN site
property line, it joins the channelized lower portion of Darlington Creek, approximately
200 meters upstream of Lake Ontario. Approximately 400 meters of the uppermost reach of the
intermittent tributary will be lost at the clearing and grubbing stage. The area of the south
tributary will be excavated for the NND station, such that the excavated area will drain towards
Lake Ontario and it is unlikely that realignment or SWM strategies could maintain the
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contribution of flow from the lost portion to the remaining downstream tributary segment and to
Darlington Creek.
The loss/alteration of these reaches is considered to represent an effect on the Darlington Creek
tributary aquatic habitat VEC. However, none of the VEC indicator species chosen for the EA
would be measurably affected. Factors that mitigate the sensitivity of Darlington Creek habitat to
the loss/alteration of these reaches include:
The affected portions of the tributaries are intermittent, and therefore do not provide
sustained flow to downstream habitats. Most contributions would occur during snowmelt
and rainfall events when flow is already high in the main branch of Darlington Creek;
The tributaries join Darlington Creek low in its watershed, where the contributions of
flow are less important to Darlington Creek hydrology and resulting habitat
characteristics. The lower reaches have been highly modified from past actitivies on
adjacent sites, and do not provide critical habitat for fish species that spawn in the creek.
The north tributary appeared to be highly ephemeral, and would have little effect on
Darlington Creek flow and habitat. The south tributary has features that suggest higher
flows than in the north swale, however its contribution is unlikely to be critical to a reach
of Darlington Creek that has been extensively altered (i.e., channelized and realigned)
and is influenced by Lake Ontario water levels and discharge from the St. Marys
operation.
Although they do not directly support fish or other aquatic species, these tributary swales meet
DFO’s definition of “indirect” or “contributing” fish habitat by virtue of their contributions to
water quality, flow, nutrients and food organisms (e.g., terrestrial invertebrates) to the
downstream fishery. DFO is therefore expected to consider the loss of the tributary to represent a
HADD that will require section 35(2) FA authorization and fish habitat compensation as part of a
comprehensive Project fish habitat compensation strategy.
In summary, the on-site construction activities may result in loss of some stream habitat due to
site excavation and soil stockpiling. The tributaries are intermittent and therefore are of low
habitat quality. Since the effects are confined to the SSA, occur only during the construction
phase, and are fully reversible with habitat compensation, the effects due to removal of the upper
reaches of the tributaries to Darlington Creek are considered to be of negligible overall
environmental impact. In addition, Geological and Hydrological Environment Assessment of
Environmental Effects TSD notes that during the Site Preparation Phase, the preparatory works
will move soil and rock from excavations around the site and groundwater flow will charge and
concludes that a higher recharge adjacent to Darlington Creek will add baseflow to Darlington
Creek and compensate for the loss of baseflow in the lower reaches of the creek.
3.3.1.3 Removal of On-Site Ponds
The ponds were constructed in a natural depression as part of OPG’s biodiversity program at the
DN site (Figure 3.3.1-1). The ponds lack strong physical connection to local streams and
tributaries. While there is the possibility of overflow and drainage into the Darlington Creek
watershed, the potential for and frequency of these occurrences seems low based on the low
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water levels typically encountered in the ponds and the lack of defined outflow channels. There
is further, topographical separation of the ponds from downstream portions of the watershed
represented by the excavated right-of-way of the CN rail line. Migration of aquatic species
upstream to the ponds is prevented by this barrier. The constructed ponds do not support fish and
appear not to contribute directly or indirectly to downstream fisheries in any measurable way.
Removal of the ponds is not expected to require a FA authorization or fish habitat compensation,
although OPG may choose to create similar habitat elsewhere to offset the loss on-site habitat
and biodiversity. An obvious opportunity to offset loss of the ponds lies in the design of SWM
facilities for the soil disposal area north of the CN rail line. Shallow wetland habitat could be
established in swales, ditches and detention ponds. Similar aquatic communities exist or are
developing on the site in several SWM facilities including Coot’s Pond and SWM ponds built in
conjunction with recent development around the DN site.
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Common aquatic plant and wildlife species reside in the ponds. Removal of Treefrog, Dragonfly
and Polliwog Ponds does not involve any of the VEC indicator species that were chosen for the
EA. A net reduction of aquatic habitats represented by shallow ponds and wetlands could occur
within the SSA, but may be offset by habitat created in SWM ponds and associated channels.
The habitat potential of SWM ponds at the DN site is demonstrated by Coot’s Pond. However,
even without SWM offsets, loss of the ponds is not expected to affect local or regional
conservation of similar aquatic habitat and associated species.
In summary, removal of the ponds will result in loss of on-site aquatic habitat, and the impact is
considered of high magnitude within the SSA since there are a limited number of aquatic habitats
on-site. The ponds provide relatively uncomplicated aquatic habitat of low sensitivity that could
be re-created elsewhere on the site. The ponds are also small in area and therefore comprise a
small fraction of similar habitat within the local and regional areas. Loss of the ponds will not
measurably affect local or regional conservation of similar aquatic habitat and associated species,
however, their loss is acknowledged as an effect of the Project, particularly in that opportunities
to mitigate the loss are readily available as noted above. Since the effects are confined to the
SSA and are fully reversible with restoration of similar habitats on-site, the effects associated
with removal of the on-site ponds are considered to be of negligible environmental impact after
mitigation.
3.3.1.4 Alteration/Disruption of Coot’s Pond
The extent of possible alteration or disruption of Coot’s Pond (Figure 3.3.1-1) is not defined, as
the final configuration of an expanded construction waste landfill is unknown. Temporary
disturbance may occur, as a bounding scenario, however, it is the intention of the Project that the
ecological attributes that have been successfully encouraged by OPG at the Coot’s Pond location
will be maintained through in-design mitigation measures incorporated for that purpose and the
affected portions of the pond will be restored.
In addition to its primary role as a SWM and settling pond, Coot’s Pond was intended to be
fishless to promote amphibian biodiversity on the DN site. The pond’s connection to the nearby
intermittent tributary is limited to its outflow structure, which provides a barrier to upstream fish
migration, should there be any fish in the adjacent watercourse. Despite this strategy a population
of northern redbelly dace has become established in the pond, likely as the result of release of
bait fish by the public. However, since the pond is a treatment facility and is very poorly
connected to nearby fish habitat, it is unlikely that DFO would consider it to be fish habitat
subject to section 35(2) FA provisions. As such, it is unlikely that effects on Coot’s Pond would
need to be addressed as part of the fish habitat compensation plan for the Project.
In summary, the existing Coot’s Pond was originally constructed as part of the on-site
stormwater management and settling pond system associated with the Northwest Landfill. The
pond now supports an attractive emergent wetland community. However, the pond provides
aquatic habitat of relatively low sensitivity and was not designed to be connected to aquatic
habitat. Further, since the effects will be kept to a minimum, are confined to the SSA and are
fully restorable following Site Preparation and Construction, the overall environmental impact of
the potential alteration/disruption of Coot’s Pond is considered to be negligible.
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3.3.1.5 Alteration of Upper Reaches of Intermittent Lake Ontario Tributary
Changes to the intermittent Lake Ontario tributary (Figure 3.3.1-1) are not defined, as the final
configuration of an expanded construction waste landfill is unknown. The worst case scenario
would entail a realignment of portions of the watercourse eastward, closer to Park Road,
combined with filling of ephemeral ditch and swale features. Although upstream migration of
fish from Lake Ontario is not possible, and the likelihood of pre-existing populations of resident
fish species is low due to the intermittent nature of the watercourse, the tributary possibly hosts
northern redbelly dace as a result of one-way migration downstream through the Coot’s Pond
outfall. Recent beaver activity has created a series of beaver ponds along the tributary that
provide more permanent aquatic habitat suitable for such fish despite the intermittent flow
regime. Changes to the tributary could therefore directly affect fish habitat and would represent a
HADD that will require section 35(2) FA authorization and fish habitat compensation as part of a
comprehensive Project fish habitat compensation strategy.
In summary, the expansion of the waste landfill may result in degradation of stream habitat
through removal and re-alignment of sections of the tributary. Since the stream is intermittent, it
is considered to be of low to moderate habitat quality and comprised of relatively simple aquatic
habitat. The loss of the affected reaches will be offset through the fish habitat compensation plan.
Therefore this is considered to be an impact of negligible magnitude.
3.3.1.6 Lake infill
Lake infill associated with the Project will involve the loss of approximately 40 hectares of
nearshore habitat along approximately 2 kilometers of shoreline (Figure 3.3.1-2), comprised of a
westerly portion of armoured and previously filled shoreline adjacent to DNGS, and an easterly
portion of natural shoreline at the foot of Raby Head. Filling along the portion in front of DNGS
will advance the previously filled and armoured shoreline in a narrow band slightly further and
deeper into Lake Ontario, resulting in some loss of nearshore habitat in approximately the 4 to
5-meter depth range but not altering shoreline conditions appreciably. Lake infill at the NND
site will be more extensive to provide necessary construction laydown area and will replace the
natural shoreline and gradual lakebed contours with an armoured shoreline adjacent to deeper
water out to approximately 5 meters depth.
A 40 hectare lake infill area represents a considerable effect on the Lake Ontario nearshore
habitat VEC on the scale of SSA and LSA, but affects only a very small proportion of the
nearshore habitat that exists within the RSA.
The exposure of the lake infill area shoreline to wind, wave and current action creates a high-
energy aquatic environment. The coarse substrates of gravel and cobbles near the beach are
frequently displaced during storms. As a result, changes in sedimentation patterns due to
alteration of the shoreline can be expected, although effects would be relatively localized. Any
sediment deposition is likely to occur further offshore, in deeper water, as a result of extension of
the shoreline into Lake Ontario.
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There may be effects due to the construction of the infill area such as increased temperatures and
possible algal growth in an embayment between Darlington Creek and the proposed lake infill
area. If monitoring indicates that algae growth in the area is expected be a problem, physical
modifications to the shoreline in the area could be undertaken. These could include minor
changes to the infill design geometry and/or further means such as additional lake infill to
enhance water circulation to flush nutrients that could contribute to algal growth, or alternatively,
measures to reduce water circulation, favouring the creation of a coastal wetland or marsh,
dominated by vascular plants that would compete with algae for nutrients.
Underwater video images were collected at 27 locations in and immediately-adjacent to the
proposed lake infill zone acquired in November 2008 during the EA studies. The images
suggested that substrates in the area could be grouped into six major categories ranging from
finer sediment (sand or silt) over bedrock to densely packed cobble and boulders
(Figure 3.3.1-2). Substrate types can be summarized as follows:
1. Finer sediments over bedrock with patches of exposed bedrock;
2. Finer sediments usually with distinct ridges and/or ripples;
3. Finer sediments with scattered gravel and cobble;
4. Gravel and cobble in a base of finer sediments;
5. Rocks ranging in size from gravel to boulders in a base of finer sediments; and
6. Densely packed cobble and boulders.
The western portion of the proposed infill area is dominated by rocky substrates. In the eastern
portion of the area, rocky substrates tended to (with some exceptions) dominate the locations
closest to shore, transitioning to more sandy substrates in deeper areas. Additionally, dead
mussel shells could be seen throughout the infill area. Shell numbers were highest in the western
portion of the potential infill area, reaching their highest densities at the eastern edge of the
armoured shoreline, becoming almost non-existent in the easternmost area of the site. This area
is not considered optimal fish spawning habitat.
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FIGURE 3.3.1-2
Distribution of Sediment Types Identified by Underwater Video within the Proposed Lake
Infill Area
Recent benthic sampling within the proposed infill area collected in November 2008 is shown in
Figure 3.3.1-3. Low invertebrate densities collected in the proposed lake infill zone were typical
of benthic communities in other high energy littoral zones of Lake Ontario where shifting
substrates, limited interstitial space and little organic accumulation result in the presence of only
relatively few, tolerant invertebrate species and populations.
FIGURE 3.3.1-3
Benthic Invertebrate Sampling Locations within the Proposed Lake Infill Area
Effects on VEC indicator species can be summarized as follows:
Benthic invertebrates – localized mortality and loss of habitat within the lake infill
footprint. However, recent benthic results shown that densities are quite low, and involve
few species. Species and community conservation will not be affected as extensive
Type 1
Type 2
Type 3
Type 4
Type 5
Type 6
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benthic invertebrate habitat exists in the LSA and RSA. Bloody red shrimp, a recent
invasive species, was also reported in the area from 2009 spring surveys (AE Existing
Conditions TSD). However, they are not expected to increase because of the lake infill;
Round goby – localized mortality and loss of habitat within the lake infill footprint.
Although round goby has become an important prey fish species in the Lake Ontario food
web, conservation of this widespread exotic invasive species is not a concern. Recent
(2009) spring surveys have indicated the dominance of this species in nearshore habitats
(AE Existing Conditions TSD);
Emerald shiner – loss of nearshore spawning, nursery and foraging habitat within the lake
infill footprint. Emerald shiner within the fill area will be salvaged prior to lake filling
and released back into the lake. Conservation of this species will not be affected as
similar habitat is extensive within the LSA and RSA;
Alewife – loss of a very small portion of the nearshore spawning and nursery area of the
lakewide alewife population. Alewife within the lake infill area will be salvaged prior to
filling and released back into the lake. Conservation of alewife will not be measurably
affected given the extent of remaining suitable habitat and the size of the alewife
population;
White sucker – loss of nearshore foraging habitat within the lake infill footprint.
However, potential benthic forage species exist at low densities and species diversity.
Spawning and nursery habitats will not be affected as they are located in tributary creeks
and rivers. White sucker within the lake infill area will be salvaged prior to filling and
released back into the lake. Conservation of the white sucker population will not be
affected as extensive nearshore habitat exists in the area and white sucker are common
and widespread;
Round whitefish – loss of a portion of potential spawning and nursery habitat, as well as
seasonal foraging habitat within the lake infill footprint. Historical distribution suggests a
wide distribution from Pickering to Port Hope (Haymes and Kolensoky 1984). However,
few larval round whitefish were observed in the vicinity of DNGS (in decline), and only
one was observed in the proposed lake infill area during the 2009 spring sampling
program (Section 3.8 of the AE Existing Conditions TSD). Most construction will likely
take place during the summer, when warm water temperature would exclude whitefish
and other coldwater fishes from the lake infill area. However, construction of the
perimeter berm is likely to extend beyond the summer months. Therefore, adult round
whitefish within the lake infill area will be salvaged and released to Lake Ontario prior to
filling within the contained area. Still, few adult fish are expected based on the population
decline of the species lakewide (Hoyle Pers. Comm. 2009). Conservation of the round
whitefish population will not be affected, as extensive similar habitat exists in the area;
Lake sturgeon – loss of a portion of foraging habitat. Sturgeon within the lake infill area
will be salvaged and released to Lake Ontario prior to filling. As the lake infill area does
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not contain critical sturgeon habitat, but represents a small portion of widespread
nearshore foraging areas, the lake infill area is not expected to affect lake sturgeon
population conservation;
American eel – loss of a portion of foraging habitat. Eels within the lake infill area will
be salvaged and released to Lake Ontario prior to filling. As the lake infill area does not
contain critical eel habitat, but is a small part of extensive nearshore feeding grounds, eel
population conservation is not expected to be affected;
Lake trout - loss of a portion of potential spawning and nursery habitat, as well as
seasonal foraging habitat within the fill footprint. Most construction will likely take place
during the summer, when warm water temperature would exclude lake trout and other
coldwater fishes from the lake infill area. However, construction of the perimeter berm is
likely to extend beyond the summer months. Therefore, lake trout within the lake infill
area will be salvaged and released to Lake Ontario prior to filling, within the contained
area. Conservation of the lake trout population will not be affected, as extensive similar
habitat exists in the area and stocking continues for this species to offset lakewide poor
natural reproductive success; and,
Salmonid sport fish – loss of a portion of seasonal foraging habitat within the lake infill
footprint. Spawning and nursery areas for trout and salmon species that make up the sport
fishery occur in tributary creeks and rivers and will not be affected by lake infill. Access
to Darlington Creek will not be altered, and changes in shoreline processes are not
expected to result in alteration of sediment deposition patterns that would prevent access
to the creek. Most construction will likely take place during the summer, when warm
water temperature would exclude coldwater fishes from the lake infill area. However,
construction of the perimeter berm is likely to extend beyond the summer months.
Therefore, trout and salmon within the fill area will be salvaged and released to Lake
Ontario prior to filling within the contained area. Risks to conservation of these species is
not of concern as their populations are maintained by stocking and natural reproduction
in tributaries beyond the influence of the lake infill.
Measurable direct mortality is therefore only likely to be associated with benthic invertebrates
and the benthic round goby VEC indicator species, which cannot be feasibly salvaged from the
fill area. However, there is no conservation concern associated with mortality of these
widespread species in such a limited area.
Although population conservation and production on a regional or lakewide scale is unlikely to
be measurably affected by the lake infill, it remains that a measurable area of habitat will be lost
that is currently productive to varying degrees for all of the VEC indicator species. Studies
confirm that the affected area is similar to extensive areas of the Lake Ontario north shore and
indicate that it is a high energy zone, with a benthic community of low density and diversity, and
little likelihood of containing critical areas of fish habitat. Still, this is the nature of fish habitat
within this portion of the nearshore and a section 35(2) FA authorization will be required, along
with fish habitat compensation measures to offset the loss of habitat and associated productivity.
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In summary, the construction of the lake infill will result in the loss of nearshore habitat, as well
as construction-related impacts, such as increased turbidity during construction of the cofferdam
and along the fill face. Since site management practices will be implemented to reduce erosion
and sedimentation, and resulting turbidity in the nearshore is expected to be similar to that which
occurs during storm events, increased turbidity is considered to be an impact of low magnitude.
Since the lake infill does not affect a meaningful proportion of habitat for any of the VEC
indicator species, there are extensive areas of similar habitat all along the north shore of Lake
Ontario, and compensation for habitat loss will be undertaken, the effects of the lake infill
structure on the aquatic habitat of Lake Ontario are considered to be of negligble overall
environmental impact.
3.3.1.7 Construction of Intake and Discharge Structures
Construction of the intake and discharge for the once-through condenser cooling water system
will interact with the AE due to blasting and excavation to connect the intake tunnel to the lake,
to prepare the lake bed for installation of the porous veneer intake structure and to install the
diffuser ports along the discharge tunnel. Blasting could involve incidental fish losses. The
porous veneer intake structure and the diffuser ports and will occupy approximately 1.1 hectares
and 0.7 hectares of the lake bed, respectively.
The intake structure will be situated in approximately 10 meters depth, in the zone that was
determined in studies conducted for the placement of the DNGS intake to be offshore of the
highest concentrations of fish and inshore of the highest concentrations of Mysis (freshwater
shrimp). The discharge diffuser will be situated along an alignment of approximately
1100 meters, similar to DNGS, but in deeper water than DNGS, ranging from approximately 10
to 20 meters.
Siting of the intake and discharge diffuser structures will minimize the interaction with the VEC
indicator species by avoiding shallow warmer water and nearshore spawning areas. Interactions
can be summarized as follows:
Benthic invertebrates – localized mortality and permanent loss of habitat within the
affected areas. Species and community conservation will not be affected as total area
affected is small;
Round goby – localized mortality and permanent loss of habitat within the affected areas.
Conservation of this widespread exotic invasive species as a forage species is not a
concern, especially since the total area affected is small;
Emerald shiner – little interaction is expected as the works avoid the primary nearshore
habitat of emerald shiner;
Alewife – localized incidental mortality of small numbers of alewife due to blasting. Area
of habitat affected is negligible against total available alewife habitat;
White sucker – little interaction is expected as the works avoid the primary nearshore
habitat of white sucker;
Round whitefish – little interaction is expected as the works avoid the primary nearshore
spawning areas of round whitefish. Incidental mortality of a few individuals could occur
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with blasting. Recent larval fish studies (spring 2009) have indicated the low relative
abundance and distribution of round whitefish in the vicinity of DNGS (AE Existing
Conditions TSD);
Lake sturgeon – little interaction is expected as the works avoid the shallow areas of the
nearshore;
American eel – little interaction is expected as the works avoid the shallow nearshore
areas;
Lake trout – little interaction is expected as the works avoid the primary nearshore
spawning areas of lake trout and total area of habitat affected is negligible against
available habitat. Incidental mortality of a few individuals could occur with blasting; and,
Salmonid sport fish – incidental mortality of a few individuals could occur with blasting.
Area of habitat affected is negligible against total habitat availability for these species.
In summary, incidental mortality of limited numbers of individuals of a few VEC indicator
species could occur due to blasting. Underwater blasting will be subject to DFO review and
likely will require section 32 authorization under the FA, for destruction of fish by means other
than fishing, which will involve development of mitigation strategies to minimize harmful
effects on fish. Since the project results in a HADD of fish habitat, the conditions associated with
a section 32 authorization under the FA will be included within the section 35(2) authorization.
Mortality of relatively small numbers of fish during the Site Preparation and Construction Phase
is not considered likely to be of conservation concern relative to the population of any of the
VEC indicator species.
A small area of habitat will be lost to the intake and discharge structures. As these areas will be
located offshore in deeper water, the loss of this habitat is not considered likely to affect any of
the VEC indicator species in a meaningful way. Nevertheless, a section 35(2) FA authorization
will be required for this and other Project works and activities, and a comprehensive fish habitat
compensation plan will offset the loss of habitat and associated productivity.
In summary, the construction of intake and discharge structures into Lake Ontario for the cooling
tower option would involve excavation of a trench and laying of pipe that could result in
temporary disturbance of habitat. Once construction is complete, habitat loss will be restricted to
the small areas of the intake and discharge structures. Blasting during construction could result in
lethality in some fish species and will be addressed through standard mitigation measures as per
DFO guidance. Sedimentation from construction activities is expected to be localized and
relatively short term and is not expected to result in mortality of benthic organsisms or
permanent alteration of nearby lake substrates.
Construction of the intake and discharge structures for the once-through cooling option would
involve tunneling beneath the lake. Therefore, lakebed disturbance is limited to the porous
veneer intake and individual diffuser ports, which would be permanent structures on the lake
bottom. The habitat loss would be restricted to the footprints of these structures, and this is
considered the bounding condition for disturbance of lake bottom habitats. Since small areas of
lake bottom will be affected, extensive areas of similar habitat are available nearby, any habitat
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loss will be offset through the fish compensation plan, and blasting effects will be mitigated, the
overall effect is considered to be negligile.
3.3.2 Operation and Maintenance Phase
3.3.2.1 Impingement and Entrainment
I&E losses have been addressed by in-design mitigation measures that include a lakebottom
porous veneer intake structure that reduces intake velocity at the interface with the lake and
placement of the structure in approximately 10 meters depth where fish and invertebrate
abundance has been shown to be low. This design is similar to the DNGS intake structure, which
has performed well in reducing I&E losses far below those that occur at other stations on the
Great Lakes. The DNGS impingement and entrainment performance was taken as a case study
for the purpose of assessment of this effect of the Project.
A separate analysis of intake losses has been undertaken concurrently with the EA, using DNGS
entrainment results from monitoring conducted in 2004 and 2006 and impingement data
collected in 2006-2007. The analysis employed modeling techniques similar to those in use in
the United States to address United States Environmental Protection Agency (USEPA)
Regulation 316(b) requirements related to fish losses. Total impingement and entrainment losses
were estimated and the losses were modeled in terms that permit comparison among years and
locations (i.e., other stations) and assessment against conservation criteria.
Overall, it is anticipated that relatively small numbers of fish and aquatic invertebrates will
comprise intake losses associated with impingement and entrainment at the NND station due to
the effectiveness of the intake design and placement. These losses are not expected to result in
measurable changes to population size, production or status of the VEC indicator species. For
small numbers of individuals removed from their respective populations, compensatory
mechanisms of recruitment, growth and survival in the remaining population are expected to
offset the losses.
3.3.2.2 Impingement
The DNGS intake design and location has been very successful in reducing impingement.
Underwater video studies showed that by maintaining low intake velocities, even small fish
could swim over it without being drawn in (Patrick and Poulton 1993). Impingement rates have
been very low compared with other generating stations on the Great Lakes, based on monitoring
undertaken by DNGS operations staff which were used as an index of effectiveness of the intake
design as a mitigation strategy. The DNGS porous veneer intake incorporates features that have
been designed to reduced water velocities at the intake as well as other fish diversion principles.
DNGS CCW intake performance is summarized in Wismer (1997a) and includes impingement
monitoring at DNGS from 1993 to 1996. These data were subsequently highlighted in the
Darlington Ecological Effects Review (DEER) (ESG 2001) to assess impingement losses
(Table 3.3.2-1). Impingement for each year ranged from 164 kg in 1996 to 555 kg in 1994. Still,
these estimates are not annualized and may be under-estimates due to errors in counting and fish
identification (Wismer 1997b). In addition, in 1994, an estimated 1,300 kg of fish, identified as
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alewife, were observed to have bypassed the screens as they were drawn from the forebay, and
were deposited in a screenhouse sump.
Approximately 97% of the fish impinged during the 1993-1996 studies belonged to five
categories, which were alewife, shiner (likely emerald and spottail shiner), rainbow smelt, sucker
(probably mostly white sucker) and whitefish (both round and lake whitefish). All other species
individually comprised only fractions of a percent of total impingement. DNGS impingement
rates have been considered too low to measurably affect the lake-wide populations of any of the
impinged species. Shiner impingement records need to be interpreted with caution as some
misidentification of smelt and alewife as shiners was known to occur, which would overestimate
shiner losses.
TABLE 3.3.2-1
DNGS Impingement Loss Estimates (1993-1996, 2006-2007)***
Year Biomass (Kg) Species Impinged
1993
1994
1995
1996
232
555*
368
164
Alewife, Shiners, Smelt, Sucker, Walleye,
Whitefish, Carp, Salmon, Lake Trout, Rainbow
Trout, Gizzard Shad, Brown Trout, Bass, Eel,
Yellow perch, Catfish, Sunfish, Others (not
speciated)
Dec 2006- Dec 2007 437- 893** Alewife, Longnose Sucker, Pink Salmon,
Rainbow Smelt, Round Goby, Spoonhead
Sculpin, Threespine Stickleback, White Sucker
* Does not include 1300 kg of alewife/debris in sump in June 1994.
** Upper biomass range (893 kg) is based on Unit 4 results (assumes other Units impinge similar
amounts as Unit 4 which is a conservative estimate). 2006-2007 data corrected for station flow.
***The current monitoring frequency for impingement is every three years. The next planned
impingement data collection at DNGS is anticipated in 2010.
Recent impingement sampling at DNGS was conducted over approximately a one-year period by
a qualified biologist from December 13, 2006 to January 9, 2008 (2006-2007 adjusted for station
flow) (SENES 2009). Sampling was typically weekly during the May to August period, and
biweekly from September to April. Although sampling methodology was not as robust as recent
USEPA 316b studies, it does still provide a recent estimate of species impinged and their relative
contributions to impingement for EA purposes. Biomass estimates for the recently collected data
are given in Table 3.3.2-1. Annual impingement was estimated to be approximately 14,119 fish
(437.5 kg). This biomass estimate is within the range from most years reported in the DEER
report (1993, 1995, 1996, but not compared to 1994 results which had significantly higher
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impingement when including fish which bypassed the screens). Still, the 2006-2007
impingement results may still be underestimated due to issues not sampling some Units during
critical impingement periods. However, Unit 4, which is the last Unit in the forebay, had the
highest impingement during the 2006-7 sampling (6,505 fish) as well as the least missed
sampling dates during critical impingement periods. Typically, Unit 4 impinges more fish as fish
become weakened, and move to the end of the forebay. If we assume the other Units impinge as
many fish as Unit 4, then, an estimated impingement would involve 26,020 fish/yr (i.e. 6,505
fish multiplied by 4 operating units) which is likely a conservative estimate. Similarly, station
biomass estimates were extrapolated based on Unit 4 data (which also had the highest values)
and were estimated to be approximately 893 kg (Table 3.3.2-1). An estimated range of
impingement at DNGS could possibly vary from approximately 14,119 (437 kg) to 26,020
(839 kg) fish/yr. In recent sampling, a total of only 8 species were collected of which alewife
and round goby contributed approximately 85.9 and 8.5 % of the total, respectively. Round goby
is a VEC indicator species (Table 3.3.2-1) which was not reported earlier in the DEER Report
(ESG 2001, 1993-1996 data sets). Although goby is a demersal species and impinged, densities
tend to be higher in the nearshore environment in the spring and summer, including at the 10-m
depth where the intake is proposed to be located (AE Existing Conditions TSD). Therefore,
goby impingement is expected to increase. Fall migration occurs to greater depths (beyond
30 m). During this migration period, goby will also come in contact with the intake structure.
However, they have excellent swimming speed capabilities (sustained speeds for short periods
up to 85 cm/s, Pennuto 2009), and should have the ability to avoid the low intake velocities of
the intake structure (average velocity of 15 cm/s). Therefore, although goby impingement is
expected to increase, it is not expected to be significant.
Recent impingement losses of the relevant VEC indicator species based on recent impingement
results can be summarized as follows:
Alewife – The estimated number of alewife impinged annually over the December 2006-
December 2007 period ranged from approximately 12,139 to 23,416 (extrapolated) fish.
These numbers are negligible relative to fish populations in Lake Ontario (Owen et al.
2003). For example, over 236,000 adult alewife were removed from Lake Ontario in
2003 (US side only) for scientific purposes alone. Furthermore, it has been estimated that
approximately 1.03 billion yearling and adult alewife occur in Lake Ontario (LOMU
2007). Still, alewife populations are on the decline and are estimated to be at levels
reported in the early 1990’s (LOC 2009).
White sucker – The estimated number of white sucker impinged annually was 100 and
10 longnose sucker in 2006-7. This is considered very low as white sucker was one of the
most numerous and frequently encountered in gillnet catches at DNGS in field studies.
To put the loss of one hundred white sucker into perspective, experimental gillnetting at
DNGS typically results in the capture (and potential mortality) of more fish on an annual
basis (assuming a seasonal sampling program).
Round Goby- The estimated number of round goby impinged annually was 1,207 fish.
This species was not impinged in earlier assessments (1993-1996, ESG 2001) but is a
recent invasive species. The species is now very well established in the nearshore
environment of Lake Ontario and other Great Lakes, and no serious impact from
impingement on this species is expected. However, an increase in impingement will
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likely be expected because of its benthic nature and high relative abundance nearshore
(AE Existing Conditions TSD). Goby populations tend to be more concentrated nearshore
in the spring and summer (see Section 3.10 of the AE Existing Conditions TSD).
Since other VEC indicator species were not impinged in the recent sampling program, they are
not discussed. In earlier impingement sampling (1993-1996), round whitefish, Americal eel,
lake trout and salmonid sportsfish were impinged; however, numbers were very low (ESG 2001).
A comparison of recent entrainment and impingement at DNGS to other power plants on the
Great Lakes is given in Table 3.3.2-2. These estimates are for general comparison only since
sampling methodologies vary as well as the number of sampling events. Still, these results
provide evidence that DNGS impinges and/or entrains fewer fish relative to other locations on
the Great Lakes which is consistent with earlier data reported by Wismer (1997a).
Although the sample size is limited (n=5), the results do suggest that there is considerable
variability in the number of organisms either entrained or impinged. Variation depends on intake
location (Great Lake), intake type (submerged or surface), and intake flow rate. It is noteworthy
that the number of species either entrained or impinged at DNGS is considerably lower than all
other plants. In addition to numbers impinged, there are also reductions in the number of species
impinged and entrained at DNGS compared to other locations. It should also be noted that some
of these plants also have fish protection devices. For example, the DC Cook (Lake Michigan)
and J.A. FitzPatrick (Lake Ontario) plants have acoustic devices installed to reduce impingement
(Dunning et al. 1992), although acoustic devices at the FitzPatrick plant operate intermittently.
The Campbell plant on Lake Michigan has a USEPA approved wedge-wire screen system which
virtually eliminated impingement, but still entrains some fish eggs and larvae.
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TABLE 3.3.2-2
Comparison of Entrainment and Impingement Estimated Losses at Different Plants on the Great Lakes
Annual Impingement Annual Entrainment
Plant LocationMWe
(gross) Flow m3/s Intake Type No. of
Species
Dominant Species
Impingement No. Impinged
No. of
Species
Dominant
Species
Entrained
(Larvae)
No. of Eggs/
Larvae Entrained
16,833,776 (2004) DNGS
Lake
Ontario3740 150
Submerged
(porous
veneer)
8Alewife
Round goby
14,119-26,020
(2006-7)3
Alewife
common carp 7,601,306 (2006)
D.C. Cook1 Lake
Michigan 2,191 106-145
Submerged
(acoustic
system)
50
Yellow perch
Alewife spottail
shiner
1,386,023 (2005-6) 11 Alewife round
goby cyprinids
105,700,000
(2005-6)
Units 1-2
(13.1)Surface 50
Alewife
Gizzard shad 491,717 (2005-6) 15
Alewife
Spottail shiner
Goby
28,129,042
(2005-6)
J. H. Campbell2 Lake
Michigan 1,200
Unit 3
(17.5)
Submerged
(wedge-wire
screen 3/8”
opening)
N.A.
(screen
size too
small to
capture
fish)
N.A. N.A. 15
Alewife
Spottail shiner
Goby
6,535,452 (2005-6)
Bay Shore3Lake Erie
(Maumee
Bay)
631 35.5 Surface 55
Emerald shiner
Gizzard shad
White perch
46,030,066 (2005-
6)26
Freshwater
drum
Rainbow smelt
Morone spp.
>2,200,000,000
(2005-6)
J.A. FitzPatrick4 Lake
Ontario886 26.1
Submerged
(acoustic
system,
operates
intermittently)
54
Stickleback
(201,563)
Alewife (16,796)
230,534 (2004) NA NA NA
Notes:
1. Data obtained from Normandeau 2007 (Report R-20452)
2. Data obtained from GLEC 2007 (Report 1765-00)
3. Data obtained from Ager et al., 2007 (Report 11206-005-RA-0001-R00)
4. Data obtained from 2004 SPDES Biological Monitoring Report James A. FitzPatrick Nuclear Power Plant (Permit No. NY 0020109, Section 10, CP-04.03).
May 2005.
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The remaining VEC indicator species differ in their susceptibility to impingement. Benthic
invertebrates, when affected by plant operations, are entrained rather than impinged, so this VEC
indicator is not included. Impingement of lake sturgeon is not expected because it is not reported
as a species impinged at DNGS. Impingement of this species is relatively unlikely given the size
of individuals encountered near DNGS in relation to the intake spacing (14 cm), and their ability
to overcome the low velocity of the intake.
Habitat VECs are not affected by intake losses. The effect on fish habitat associated with the
construction and continued presence of the intake structure was addressed as a habitat loss and
offset by fish habitat compensation as a Site Preparation and Construction phase effect.
The NND intake design for once-through cooling will be similar to the DNGS intake and is
expected to be similarly effective in reducing intake velocity and fish impingement. However,
the NND once-through cooling flow has been estimated at 250 m3/s compared to the existing
flow rate at DNGS of 150 m3/s (SWE Effects TSD). To estimate fish losses at the predicted
intake volume of 250 m3/s, a simple linear adjustment was applied to the losses at DNGS.
As stated above, the estimated range of fish impinged at DNGS was from 14,119 to 26,020
fish/yr (approximately 437 to 893 kg) based on the December 2006- December 2007 data.
Assuming impingement between the existing DNGS and the proposed NND (based on the
bounding scenario, once-through cooling option) is based on flow rates alone and have similar
intake velocities, an estimated impingement for the NND would be expected to range from
approximately 23,579 to 43,463/year fish (approximately 731 to 1347 kg, see Table 3.3.2-3
below), which assumes a linear extrapolation between flow volume and impingement, and is
based on professional judgement. Nevertheless, even if this number was doubled, the number
impinged would be low in relation to what has been reported as other at other power plant
facilities on the Great Lakes for impingement (Table 3.3.2-2) and lake-wide populations. In
addition, no SARA/ESA species are expected to be impinged. If impingement occurs, for
example with American eel, an adaptive management plan will be used to consider other
mitigation measures.
TABLE 3.3.2-3
Estimated Total Annual Impingement Losses
DNGS NND
Flow (m3/s) 150 250
Mean Intake Velocity (cm/s) <15 <15
Impingement (estimated) 14,119 – 26,020 fish
(437 to 893 kg)
23,579- 43,463 fish ± 100%*
(731 to 1347 kg)
* Confidence limits (100%) have been assigned since estimates are likely quite variable
Impingement predictions for the NND cooling tower option were based on comparisons with
other intakes on the Great Lakes. Assuming a small diameter pipe for the cooling tower intake
option, an estimate of impingement can be obtained based on operating experience at other
facilities, such as the J.A. FitzPatrick Plant on Lake Ontario, which has a submerged intake, a
relatively small intake diameter (3.3 m) pipe, and a fish protection system (only intermittently
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operated). An estimate of alewife impingement was calculated taking into account the different
flow rates (26.1 m3/s compared to 6 m
3/s for the cooling tower option). Alewife is used for
comparison since it is the dominant species impinged at DNGS and other power plants on Lake
Ontario. A predicted estimate of alewife impingement for the cooling tower option, based on the
impingement at the FitzPatrick Plant, is 3,906 fish/year (121 kg, Table 3.3.2-4). This analysis
assumes a linear relationship between impingement and flow rates at these Plants, and similar
intake pipe diameters which is unlikely since the pipe for the NND cooling tower option would
be smaller in size and would have a much lower flow rate. It also does not take into account
reductions due to the fish acoustic system in place which operated intermittently. Consequently,
based on professional judgement, this estimate is likely +/- 100%.
As an intake diameter pipe is reduced in size, a fish avoidance response would also occur due to
space perception cues. For example, Patrick and Rkman-Filopovic (2004) have shown that
schooling pelagic species such as alewife tend to avoid smaller sized openings based on space
perception cues, compared to other more demersal species such as round goby. These
experiments involved determining fish passage and encounters to different sized pipes (0.34 to
1.0 m) and configurations (angled, straight etc).
TABLE 3.3.2-4
Estimated Alewife Impingement for the Cooling Tower Option
PlantFlow Volume
(m3/s)
Intake
Diameter
(m)
Impingement
No. Annually Fish Species
J.A. FitzPatrick *
(Lake Ontario) 26.1 3.3 16,796 Alewife
NND Cooling
Tower6 Unknown
3,906+/-
100%**
(121 kg)
Alewife
* Data obtained from 2004 SPDES Biological Monitoring Report James A. FitzPatrick Nuclear Power Plant
(Permit No. NY 0020109, Section 10, CP-04.03). May 2005.
** Estimates are likely quite variable so a high confidence level has been assigned (100%) based on Best
Professional Judgement.
Alewife impingement for the NND cooling tower option is estimated to be 3,906/year +-100%
individuals. As such, it is concluded that less than 10,000 fish would be expected to be
impinged, on an annual basis with the cooling tower option with the majority of fish being
alewife. Smaller pipe systems (1.0-1.2 m) currently in place in Lake Ontario for water treatment
and other water usages impinge very few fish. Impingement for the NND cooling tower will be
dependent on location, pipe diameter, flow rate and flow velocity. Design requirements for the
cooling tower intake must take into account fish behavioural principles in order to reduce
impingement. Therefore, the cooling tower option will include fish deterrents and/or other
mitigation to further reduce impingement and entrainment losses.
In summary, the operation of the once-through cooling system (bounding scenario) or the
cooling tower option will result in impingement of negligible numbers of VEC fish indicator
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species relative to their populations in Lake Ontario. Since the effects are confined to a small,
relatively unproductive area of the SSA around the offshore intake, and are minimized by the
design that reduces water velocity at the intake and is based on fish diversion principles, the
effects on VEC indicator species populations in Lake Ontario due to impingment of fish are
considered to be of very low overall environmental impact. No SARA/ESA species are expected
to be impinged or entrained.
OPG accepts the obligation under the FA to provide acceptable and adequate
mitigation/compensation measures for the potential impacts to fish and fish habitat relating to the
NND Project. The final mitigation/compensation plan will fulfill the requirements for an
authorization under section 35(2) of the Act (HADD). The final plan will also contain
components that will address the requirements under section 32 of the FA (for the destruction of
fish by any means other than fishing).
3.3.2.3 Entrainment
To mitigate entrainment of fish and aquatic invertebrates, the DNGS intake was installed at a
10 m depth of water. This area of the nearshore near DNGS had been determined to be offshore
of the highest concentrations and diversity of fish eggs and fish larvae, and inshore of the highest
concentrations of Mysis, a shrimp-like aquatic invertebrate (Maher 1980). Entrainment is
extremely unlikely for the early life stages of fish that spawn in tributary streams or nest in
protected warmwater habitats of coastal marshes. Entrainment is therefore only likely for those
species that spawn in the nearshore.
The DEER (ESG 2001) summarized entrainment effects as involving mainly alewife, rainbow
smelt and slimy sculpin. Although estimated numbers of larvae lost to entrainment were high
during the 1993 and 1995 studies cited in ESG 2001, the numbers of equivalent adults were
considered negligible to lakewide populations of alewife and smelt at that time. The population
context was not as firm for assessment of the importance of approximately 8,000 equivalent
adult slimy sculpin, which was noted to have suffered a lake-wide decline, likely as a result of
food web changes. Entrainment studies conducted at DNGS in 2004 (Ager et al., 2005) and
2006 (Ager et al., 2006) failed to detect slimy sculpin. Very few eggs or larvae were detected.
The species observed in the samples were limited to alewife, smelt, freshwater drum and
common carp. Losses were estimated in terms of total numbers of larvae and also adult
equivalents. In 2004, it was estimated that 15,631,833 eggs and 1,201,943 larvae were entrained.
Entrained organisms represented 1,318 age-1 equivalent smelt and alewife. Production foregone,
the biomass which would have been produced if fish were not entrained, was estimated to be
only 46.2 kg. These estimates may be underestimated since sampling period was limited to the
June 14 to August 31 period (Ager et al., 2005). More intensive sampling occurred in 2006
which ocurred over the March 23 to September 23 period (Ager et al., 2006). In 2006, it was
estimated that 605,059 eggs and 6,996,246 larvae were entrained annually. Entrained organisms
represented 11,548 age-1 equivalent alewife, common carp and freshwater drum. These
relatively small estimated losses were not considered meaningful to populations of these species.
They are also low relative to other power plants on the Great Lakes (Table 3.3.2-2).
Invertebrate entrainment was also addressed in ESG 2001 and in Ager et al., 2006. Although
estimates of chironomid, amphipod and Mysis losses involved large numbers, the respective
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studies cited high nearshore densities and huge lake populations of these organisms and
concluded that they are unlikely to be affected.
Entrainment losses relevant to the VEC indicator species can be summarized as follows:
Benthic invertebrates – not entrained in numbers sufficient to affect large populations;
Emerald shiner – not detected in recent sampling. Spawning and nursery areas inshore of
intake;
Alewife – egg/larvae losses equivalent to thousands of adult females (negligible to
lakewide population of 1.03 billion, LOMU 2007); although still high, alewife population
have declined to levels reported in the early nineties (LOC 2009).
Round goby – not detected in recent sampling. Benthic habits may limit susceptibility to
entrainment;
White sucker – not detected in recent sampling. Spawning and nursery areas are in
tributaries, well removed from intake;
Round whitefish – not detected in recent sampling. Spawning and nursery areas are in the
Lake Ontario nearshore, resulting in continued susceptibility to entrainment. However,
lakewide populations are on the decline (Hoyle, 2009), and few round whitefish larvae
have been reported in the vicinity of DNGS during spring 2009 studies (see Section 3.8
of the AE Existing Conditions TSD).
Lake sturgeon – not detected in samples. Spawning and nursery areas for small juveniles
likely do not include the nearshore adjacent to the DN site;
American eel – egg/larval life stages are marine. Entrainment is not possible;
Lake trout – not detected in sampling. Successful reproduction of this species offshore of
the DN site remains unconfirmed and is doubtful given low incidence of reproduction of
this population in Lake Ontario. Entrainment could occur in future if lake trout natural
recruitment picks up; and,
Salmonid sportfish – not detected in sampling as the trout and salmon species spawn and
pass their early life history in tributary streams (or hatcheries). There is no entrainment
pathway for these species.
Entrainment at NND is expected to similarly be dominated by alewife and smelt, the two most
numerous fish species that spawn and occur as larvae in the nearshore. Although the 250 m3/s
once-through flow is expected to entrain more fish than DNGS, the losses are expected to remain
on the level of thousands of adult alewife equivalents against lake-wide populations numbering
estimated at 1.03 billion (LOMU 2007). Although these alewife estimates are still very high,
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lakewide populations of alewife have declined to levels reported in the early nineties (LOC
2009). Still, there is also the need to increase the forage base in Lake Ontario for some species
but not alewife (since they are not considered an optimal prey species for predators such as lake
trout and introduced atlantic salmon). Partly for this reason, LOMU and state agencies are
investigating stocking programs involving ciscoes and lake herring (not alewife) to increase the
forage base (Honeyfield Pers. Comm. 2009).
Entrainment of other fish species is expected to be low, related only to the incidental capture of
some species and a lack of an entrainment pathway for those species that do not spawn or pass
early life stages in proximity to the intake. Invertebrate entrainment is expected to be limited to
the extremely abundant chironomids and amphipods, the populations of which are unlikely to be
affected. Assuming that its intake location would be chosen to minimize contact with aquatic
organisms, similar to once-through cooling, the entrainment losses related to a cooling tower
option at the NND are expected to be very low since the 6 m3/s intake of makeup cooling water
and service water is considerably less than the DNGS and NND flow rates.
In summary, the operation of the once-through cooling system (bounding scenario) will result in
the entrainment of invertebrates as well as the eggs and larvae of some fish. The effects will be
confined to a small area of the SSA around the intake that is located in an area of low larval fish
and invertebrate density. The effects are further mitigated by design features that include
reducing water volocity at the intake. Historical and recent entrainment monitoring has failed to
detect entrainment losses that would affect populations. The existing DNGS intake structure has
been designed to mitigate entrainment and impingment mortality and the NND intake structure
will be at least as effective in minimizing the impingement and entrainment. The estimated
numbers entrained and impinged at NND (based on DNGS data) are considerably lower than
other power plants on the Great Lakes, and would be negligible relative to lake-wide
populations.
OPG accepts the obligation under the FA to provide acceptable and adequate
mitigation/compensation measures for the potential impacts to fish and fish habitat relating to the
NND Project. The final mitigation/compensation plan will fulfill the requirements for an
authorization under section 35(2) of the Act (HADD). The final plan will also contain
components that will address the requirements under section 32 of the Fisheries Act (for the
destruction of fish by any means other than fishing).
3.3.2.4 Thermal Discharge: Once-Through Cooling System
An offshore discharge diffuser was installed at the DNGS to enhance mixing of the thermal
effluent with lake water and limit the development of a thermal plume. Performance of the
DNGS diffuser has met expectations (Romanchuk and Burchat, 1997; Kissel, 1997) by
preventing the dispersion of heated water more than 2oC above ambient beyond a mixing zone
along the diffuser alignment. The design of the diffuser is such that mixing and dilution occurs
rapidly and there is minimal contact of heated water with lake bed substrates and no propagation
of an extensive thermal plume as occurs with stations that employ surface discharge channels.
These studies found that under cold weather conditions, the thermal plume mixed vertically with
the water column before dispersing as a “diving plume” of more dense 4oC mixed water beneath
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colder ambient lake water. This slight elevation of lakebottom temperature, within the range of
naturally occurring winter water temperatures, was considered unlikely to harm round whitefish
eggs or larvae. Diving plumes were also found to occur during the summer in conjunction with
upwellings of colder water from the hypolimnion of Lake Ontario that cause wide natural
fluctuations of nearshore water temperature. Occurrence of these plumes during the summer does
not coincide with the spawning or incubation period of any fish species known to spawn in this
area of the Lake. Otherwise, under warm water conditions, the plume was found to mix vertically
with the water column within the mixing zone, the warmer mixed water forming a buoyant
plume in the vicinity of the diffuser.
The use of a discharge diffuser was also assessed as a physical effect by the SWE component
and presented in the corresponding SWE – Assessment of Environmental Effects TSD. The SWE
assumed that once-through cooling at NND would raise the temperature of discharged water 9oC
above Lake Ontario ambient water temperature. This scenario would employ a diffuser of similar
pattern but scaled up in terms of port diameter to allow 250 m3/s flow. Operation of this diffuser,
which would extend into deeper water than the DNGS discharge due to bathymetry differences
between the sites, is expected to be similar to or better than the DNGS in terms of mixing
performance.
SWE also considered a once-through scenario with a higher discharge temperature (15.6oC) but
correspondingly lower flow (since the required amount of cooling is constant). Their model
confirmed a similar area of mixing zone and similar temperatures in the vicinity of the diffuser
line, apart from the higher temperature at the mouths of the ports. As such, the more
“conventional” 9oC scenario was evaluated and would be considered to bound, or at least
approximate, the 15.6oC option.
For the purpose of the AE assessment of effects, it was considered that the Lake Ontario
nearshore habitat VEC could be further affected, to some extent, by thermal discharge outside of
the Operation and Maintenance Phase mixing zone. Thermal addition within the narrow mixing
zone along the diffuser line was not considered as this area was considered part of the footprint
of the diffuser and it would be appropriate to offset changes to habitat suitability resulting from
scour, high water velocity, turbulence and elevated water temperature as part of a fish habitat
compensation plan for the Project. As such, this assessment focuses on the temperature
conditions in the habitats surrounding the mixing zone. Outside of the once-through mixing
zone, water temperature may be elevated and the suitability of the habitat may be addressed by
considering the likelihood of effects on relevant VEC indicator species.
VEC indicator species vary in their potential to be influenced by the thermal discharge. Since the
discharge diffuser mitigates contact of thermal effluent with the lakebottom, there is little
expectation of effect on benthic and demersal organisms. Lake bottom contact can occur with
4°C water during the winter, and in conjunction with upwelling events in the summer, but this
temperature is similar to lakebottom ambient and is not deleterious to any of the VEC indicator
species during those seasons. For example, round and lake whitefish egg and larval development
are not expected to be significantly affected by temperature changes of this nature in areas
beyond the mixing zone.
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The assessment of thermal effects on VEC indicator species was conducted through comparison
of calculated MWATs to the temperature thresholds for the VEC indicator species. The
assessment was based on the understanding that where the predicted temperature exceeds the
optimal temperature range for a particular fish VEC, there was potential for an adverse effect.
MWAT values were obtained from earlier studies conducted by Romanchuk and Burchat (1997)
which is referenced in the SWE- Existing Conditions TSD. Table 3.3.2-5 summarizes the
maximum change in temperature for bottom sensors placed over the December to April period
(1990-1996) along the perimeter of the mixing zone. During the 1993 to 1996 period 3 to 4
generating units were in operation. Although the data is limited, the estimated per cent of time
when temperature changes exceeded 2oC was typically less than 5%. The potential effects of
thermal discharge on developing whitefish eggs during the winter period were assessed through
detailed laboratory simulation studies (Griffiths 1979, 1980). Temperature rises above ambient
from 2oC to 10
oC were included. In the simulation runs, temperature elevations were applied
continuously, for 75% of the time, or for 25% of the time. Periodic exposure to elevated
temperatures was less deleterious than continuous exposure, but survival declined sharply when
eggs were cycled to temperatures above 7oC. Computations indicated that survival would be
maintained at 75% of expected ambient levels if constant temperature increases were limited to
3.5oC. Periodic increases (25% of time) of 5
oC would have a similar effect. Furthermore,
additional simulations under the worst (warmest) conditions concluded that continuous
elevations above ambient of 0.5oC to 1
oC or periodic (25-75% of the time) elevations of 2
oC to
2.5oC will have little adverse effect. Most of the VEC indicator species, including round
whitefish of all life stages, are benthic or demersal species.
It is also noteworthy that few larval round whitefish were found in surveys conducted in the
spring of 2009 (based on 84 sampling events), and that adult whitefish populations are on the
decline (Hoyle, 2009). Round goby are now the dominant larval benthic species in the vicinity
of DNGS (see Section 3.8 of the AE Existing Conditions TSD).
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TABLE 3.3.2-5
MWAT Above Ambient Values along the Perimeter of the Mixing Zone
December 1990-March 1991 Period
Instrument ID* Bottom Sensors
Maximum Temperature Change
(oC)
Estimated Percent Occurrence
TD 31 0.9 <20 TD 34 2.6 <5 TD 35 2.7 <5 TD 38 1.7 <5 TD 42 1.3 <5 TD 45 2.5 <5 TD 52 1.8 <5 TD 55 2.6 <5 CM 10 2.0 <5
*The locations of bottom sensor along mixing zone are contained in the SWE Existing
Conditions TSD, and Romanchuk and Burchat 1997.
December 1992-April 1993 Period
Instrument ID* Bottom Sensors
Maximum Temperature Change
(oC)
Estimated Percent Occurrence
TD 31 1.4 <5 TD 34 3.2 <5 TD 35 4.0 <5 TD 38 2.3 <5 TD 42 1.5 <5 TD 55 3.3 <5
*The locations of bottom sensor along mixing zone are contained in the SWE Existing
Conditions TSD, and Romanchuk and Burchat 1997.
December 1993-April 1994 Period
Instrument ID*
Bottom Sensors
Maximum Temperature
Change
(oC)
Estimated Percent
Occurrence
TD 34 3.1 <5
TD 45 2.4 <5
TD 52 2.1 <5
TD 55 3.3 <5
CM 10 1.9 <5
*The locations of bottom sensor along mixing zone are contained in the SWE Existing
Conditions TSD, and Romanchuk and Burchat 1997.
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December 1994-April 1995 Period
Instrument ID*
Bottom Sensors
Maximum Temperature
Change
(oC)
Estimated Percent
Occurrence
TD 31 1.0 <5
TD 34 2.7 <5
TD 35 3.5 <5
TD 42 2.1 <5
TD 45 2.5 <5
CM10 2.5 <5
*The locations of bottom sensor along mixing zone are contained in the SWE Existing
Conditions TSD, and Romanchuk and Burchat 1997.
December 1995-April 1996 Period
Instrument ID*
Bottom Sensors
Maximum Temperature
Change
(oC)
Estimated Percent
Occurrence
TD 31 1.2 <5
TD 34 2.7 <5
TD 42 1.7 <5
TD 45 2.4 <5
TD 52 2.2 <5
TD 55 2.9 <5
CM 10 1.9 <5
*The locations of bottom sensor along mixing zone are contained in the SWE Existing
Conditions TSD, and Romanchuk and Burchat 1997.
Winter water temperature conditions in the area surrounding the diffuser mixing zone were little
elevated above ambient nearshore temperatures and were not considered deleterious to any of the
VEC indicator species and their life stages during that season (SWE TSD). This was particularly
evident for whitefish egg and larval development, which could be considered the VEC indicator
species most sensitive to changes in winter water temperatures. This result is expected, given that
the diffuser is designed to mitigate the propagation of extensive thermal plumes and contact of
heated water with the lake bottom by promoting mixing up into the overlying water column.
MWAT values for the summer period were also reviewed to determine whether thermal addition
during the period of highest ambient nearshore water temperatures could elevate water
temperature conditions sufficient to harm fish. The highest MWAT values during summer were
approximately 24oC, and these occurred during the month of August, when background
nearshore water temperature reached the low 20’s. The small temerature difference is ascribed to
the mitigative effect of the diffuser system which, as described above, was designed to promote
rapid mixing of heated water within a relatively small area along the diffuser line. The likelihood
of the highest MWAT to affect the relevant VEC indicator species is presented in relation to
published preferred, optimum and avoidance temperatures (Wismer and Christie 1987) as
appropriate:
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Emerald shiner – the diffuser is in adult shiner habitat. Preferred summer temperature is
22-25oC. Optimum temperature is 24-28.9
oC. Since the maximum MWAT is within these
ranges, no adverse effects of increased temperatures are predicted for emerald shiner.
Alewife – the diffuser is in primarily adult alewife habitat. Juveniles can be found in
warmer inshore waters and have higher temperature tolerances. The maximum MWAT of
24oC is within the adult preferred range of 18.8-28.3
oC and therefore, no adverse effects
on the alewife are predicted.
Salmonid sportfish – none of these fish have spawning or nursery habitat near the
diffuser. The maximum MWAT is above the optimum and upper avoidance temperatures
of the salmonids and could render a portion of the area around the diffuser mixing zone
unattractive to these species during warm water periods in August. However, salmonids
are cold water species that tend to occur in the colder, deeper areas of the lake during the
summer months. As a result, salmonids are not likely to frequent the warm nearshore
waters during the month of August due to generally higher ambient temperatures in these
areas.
3.3.2.5 Comparison of Weekly Maximum Hourly Temperatures (WMHT) to Round Whitefish Temperature Benchmarks
In addition to the MWAT investigation conducted, weekly hourly maximum temperature data
from the DNGS Thermal Plume Study (Romanchuk and Burchat 1997) were compared to round
whitefish temperature benchmarks. These data are the maximum hourly water temperature
recorded in a one week period from temperature dataloggers placed at the bottom of Lake
Ontario, 9 to 22 metres below surface, in the DNGS Thermal Plume Study area (SWE Existing
Conditions TSD). Data from January 1993 to June 1996 were assessed during which period 3 to
4 generating units were in operation. The January to March period is the time interval when most
egg development is expected to occur. This represents an assessment of the worst-case
conditions, since the greatest temperature increase is likely to occur with 3 to 4 units in
operation.
Table 3.3.2-6 shows the various lifestages for the round whitefish as well as the corresponding
temperature benchmarks that were used in this assessment. Egg survival and hatching are the
most sensitive lifestages of the round whitefish and occur in the winter and early spring months.
Consequently, the assessment focused on these early lifestages. The weekly maximum hourly
temperatures (WMHT) recorded in the winter months (Table 3.3.2-7) were compared to the
round whitefish temperature benchmarks for egg survival and hatching (Table 3.3.2-6). The
short–term mortality threshold of 5ºC for embryo survival was selected for this assessment, since
the hourly maximum temperatures represent a short-term acute exposure. Weekly average
temperatures, as discussed in the previous section, are lower, and would represent long-term
chronic exposures that would be assessed against the optimum temperature benchmark.
Lake Ontario ambient water temperatures are not greatly different today compared to when the
data was collected. Tables 3.3.2-8 and 3.3.2-9 show available meteorological data from
Environment Canada weather station at Pearson International Airport for 1993 to 1996 and 2007
to 2009. Year to year variability exists in the mean temperatures and total precipitation, but there
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was no obvious increase in temperature from 1996 to 2009. Therefore, the 1993 to 1996 data
was considered adequate for this analysis.
The one-hour weekly maximum temperatures are worst case scenarios that would only occur a
fraction of the time, but assumed to occur 100% of the time. Where the recorded temperatures
are below the temperature benchmarks for the round whitefish, there is very low probability that
the round whitefish will be impacted by a change in water temperature.
TABLE 3.3.2-6
Maximum Weekly Average Temperatures ( C) for Round Whitefish
Life stage Optimum
temp.
Upper
lethal temp.
Short Term
Mortality
Embryo - - 5
Egg Survival 1-5 - -
Hatching 2.2 - -
Larvae 3 - -
Fry - - -
Juvenile 15a 24.8b -
Adult 15a 24.8b -
Spawning 3 – 4.5 - - a lake whitefish data, unspecified life stage b lake whitefish data, young of the year
All other values are calculated based on data from Wismer and Christie [1987]
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TABLE 3.3.2-7
Weekly Maximum Hourly Temperatures (WMHT) from the DNGS Thermal Plume Study
Data (ºC)
Diff
Start
Diff
End
Mix
Off
Mix
Near
Mix
East
Start
Mix
East
End
Mix
West
Start
Mix
West
End
IntakeSite
TD38 TD35 TD34 TD31 TD52 TD55 TD42 TD45 CM10
Depth 10 12 22 07 10 14 09 10 10
Bottom Yes No Yes Yes Yes Yes Yes Yes Yes
Start Year 1990 1990 1990 1990 1990 1990 1990 1990 1983
End Year 1995 1995 1995 1995 1995 1995 1995 1995 1996
Season Week Start of Week
Winter 1 1/1/1993 3.3 4.4 4.1 2.5 3.8 2.6
Winter 2 1/8/1993 3.2 4.1 3.9 2.3 3.5 2.5
Winter 3 1/15/1993 2.3 3.8 3.4 1.4 2.5 1.6
Winter 4 1/22/1993 3.8 4.4 3.8 2.5 4 3.1
Winter 5 1/29/1993 3.1 4.6 3.3 1.7 3.4 2.1
Winter 6 2/5/1993 2.6 3.7 3.4 1.6 2.7 1.7
Winter 7 2/12/1993 1.9 2.3 1 2 1
Winter 8 2/19/1993 1.7 2.8 1.3 1.9 1.5
Winter 9 2/26/1993 1.5 3.1 1.5 1.7 1.3
Winter 10 3/5/1993 2.3 3.1 1.5 2.5 1.4
Winter 11 3/12/1993 2.3 2.8 1.3 3.3 1.4
Winter 12 3/19/1993 2 3.8 1.8 2.2 1.9
Winter 52 12/24/1993 6.1 4.3 5 4.1 4.4
Winter 53 12/31/1993 1.8 3 2.1 2
Winter 53 1/1/1994 2.6 3.4 2.9 2.8
Winter 54 1/8/1994 1.5 2.1 2.2 1.5
Winter 55 1/15/1994 1.1 1.8 1.4 1.1
Winter 56 1/22/1994 1.3 2 2 1.4
Winter 57 1/29/1994 1.6 2.2 2.2 1.6
Winter 58 2/5/1994 1.4 2.1 2.4 1.4
Winter 59 2/12/1994 1.1 1.6 2.2 1.1
Winter 60 2/19/1994 2 2.3 2.5 2
Winter 61 2/26/1994 1 1.7 1.9 1
Winter 62 3/5/1994 2 2.8 2.7 2.1
Winter 63 3/12/1994 2.4 3 2.6 2.4
Winter 64 3/19/1994 3.2 3.6 3.2 2.7
Winter 104 12/24/1994 5.6 4.3 4 4.7 4
Winter 105 12/31/1994 4.3 3.7 3.4 4.4 3.5
Winter 105 1/1/1995 4.7 4.4 3.3 3.8 3.7
Winter 106 1/8/1995 3.2 2.7 1.7 2.4 2
Winter 107 1/15/1995 3.5 1.7 1.2 2.3 1.2
Winter 108 1/22/1995 4.3 3.4 2.6 3 2.4
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Diff
Start
Diff
End
Mix
Off
Mix
Near
Mix
East
Start
Mix
East
End
Mix
West
Start
Mix
West
End
IntakeSite
TD38 TD35 TD34 TD31 TD52 TD55 TD42 TD45 CM10
Winter 109 1/29/1995 4.1 4.2 3 3.2 2.6
Winter 110 2/5/1995 3.7 2.6 2.2 3.1 1.9
Winter 111 2/12/1995 3.2 2.6 1.6 1.8 1.9
Winter 112 2/19/1995 4.1 3.4 2.5 4.2 2.7
Winter 113 2/26/1995 3.8 4.9 3 3.8 2.9
Winter 114 3/5/1995 3.8 2.6 2.2 2.9 2
Winter 115 3/12/1995 4.5 3.3 3 3.4 2.3
Winter 116 3/19/1995 5.1 4.1 3.9 3.8 3.7
Winter 156 12/24/1995 2.5 3.9 2.2 2.4 2.9 2.1 2.5 2.5
Winter 157 12/31/1995 2.8 4.3 2.2 2.7 3.2 2.4 2.7 2.5
Winter 157 1/1/1996 2.7 4.6 2.4 2.6 2.8 2.7 3.6 2.7
Winter 158 1/8/1996 1.7 3.1 1.6 1.9 2.2 1.7 2.2 1.7
Winter 159 1/15/1996 2 2.8 1.4 1.8 2.2 1.6 2.2 1.5
Winter 160 1/22/1996 2.2 3 1.6 1.9 2.7 1.7 2.7 1.8
Winter 161 1/29/1996 2.5 3.1 1.7 2.6 2.8 2 2.5 2.3
Winter 162 2/5/1996 2 3.3 2.1 2.1 2.4 2 2.2 2.1
Winter 163 2/12/1996 3.1 3.8 1.9 2.6 3.5 2.2 2.7 2.3
Winter 164 2/19/1996 1.7 3.1 1.6 1.4 2.1 1.6 2.4 1.3
Winter 165 2/26/1996 3.3 4.1 2.7 3.3 3.5 2.6 3.2 3
Winter 166 3/4/1996 2.7
Winter 167 3/11/1996 1.5
Winter 168 3/18/1996 2.6
Note: Values shaded in light grey exceed the round whitefish hatching benchmark of 2.2°C.
Values shaded in dark grey exceed the round whitefish short term maximum temperature for round whitefish embryo
survival of 5°C.
As shown in Table 3.3.2-7 and Figure 3.3.2-1, there are only 3 one day exceedances of the short
term maximum temperature for round whitefish embryo survival and these all occurred at one
location (offshore of the diffuser) over the 37 month period evaluated. These temperature
exceedances occurred either early in the winter, as water temperatures were decreasing, or in the
spring, as the lake was beginning to warm up. No exceedances occurred during January or
February, when the eggs and embryos would be undergoing development, and would be most
sensitive to temperature increases. Therefore, it is unlikely that embryo development would be
affected by any changes in water temperature.
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TABLE 3.3.2-8
Mean Air Temperatures Recorded from Environment Canada’s Weather Station at
Pearson International Airport (°C)
1993 1994 1995 1996 2007 2008 2009
January -4 -12.4 -3.1 -6.7 -2.9 -2.1 -8.8
February -8.4 -8.3 -7.3 -5.8 -8.4 -5.3 -3.7
March -2 -0.8 1.9 -2.8 0.4 -1.7 0.8
April 6.6 7.3 4.1 4.4 6.1 9.5 NA
May 12.1 11.8 13.3 11.6 14.3 11.8 13.1
June 17.1 19.1 19.9 18.6 20.8 19.6 17.5
July 21.7 21.5 21.9 19.6 21.3 21.5 -
August 21.1 18.7 21.8 20.7 22.4 19.7 -
September 13.6 15.9 14 16.5 18.4 16.9 -
October 7.9 10 11 9.2 14.2 9 -
November 3.1 5.4 1 0.9 2.6 2.9 -
December -2.7 -0.1 -5.1 -0.4 -2.3 -3.1 -
NA- not available
TABLE 3.3.2-9
Total Precipitation Recorded from Environment Canada’s Weather Station at Pearson
International Airport (mm)
1993 1994 1995 1996 2007 2008 2009
January 70.6 61 133.3 72.6 38.6 58.2 44.4
February 26.6 20.2 20.8 38.2 24.6 107.6 73.6
March 31 51.2 50.8 36.2 33.4 61.6 68.8
April 85.4 96 76.6 101.6 60.8 54.6 NA
May 51.6 78.8 87 90.6 73.6 68.8 60.8
June 133.8 54.4 52.1 118 43.2 110.4 70.2
July 87.7 83 55.4 97.4 47.4 193.2 -
August 39.9 60.1 135.4 48.2 20.8 92.6 -
September 59.2 51.4 27.5 166.2 28.6 83.4 -
October 71 27.4 131.8 75.8 41.2 39.6 -
November 65.2 84.9 121.6 29.8 87.8 79.8 -
December 28.8 51.4 35.8 95.2 92.7 99.8 -
NA- not available
The results of the assessment indicate that under conditions where 3 to 4 units were in operation,
there is no concern with acute exposure of developing eggs or embryos during the critical winter
period. Short-term maximum temperatures were below the temperature threshold, and under
similar operating conditions at NND, no effects on round whitefish development would be
expected to occur.
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FIGURE 3.3.2-1
Weekly Maximum Hourly Temperatures (1993-1996)
0
5
10
15
20
25
1Jan93
5Feb93
12Mar93
16Apr93
21May93
25Jun93
30Jul93
3Sep93
8Oct
93
12Nov93
17Dec93
15Jan94
19Feb94
26Mar94
30Apr94
4Jun94
9Jul94
13Aug94
17Sep94
22Oct
94
26Nov94
31Dec94
29Jan95
5Mar95
9Apr95
14May95
18Jun95
23Jul95
27Aug95
1Oct
95
5Nov95
10Dec95
8Jan96
12Feb96
18Mar96
22Apr96
27May96
Week
Temperature
(°C)
TD31 Near Shore Mix TD42 Diffuser Start West Mix
TD38 Diffuser Start TD52 Diffuser Start East Mix
TD45 Diffuser End West Mix TD35 Diffuser End
TD55 Diffuser End East Mix TD34 Offshore Mix
CM10 Intake Short Term Max Embryo Survival
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The Lake Ontario nearshore habitat VEC will not be substantially affected by the operation of
the CCW discharge diffuser as species are unlikely to be excluded by unsuitable temperatures.
Effective operation of a diffuser, as demonstrated at DNGS, will not substantially affect the VEC
indicator species, either individually or in terms of population conservation, as MWAT and
WMHT values adjacent to the mixing zone are not considered likely to be harmful.
In summary, the operation of the once-through cooling system, as the bounding scenario, will
result in the localized discharge of warmer water. This will be confined to a small mixing zone
around the diffuser. The effects are confined to a small area of the water column around the
diffuser and do not affect critical fish habitat on the lake bottom. Furthermore, the design
promotes mixing and therefore, dissipation of heat. Therefore, the effects due to thermal
discharge are considered to be of negligible overall environmental impact. With its offshore
submerged intake and its offshore multi-port diffuser, DNGS is employing Best Available
Technology in terms of thermal discharge effects (CNSC 2006). Since the existing DNGS
diffuser has been designed to mitigate thermal discharge effects and the NND diffuser will be at
least as effective in minimizing the thermal discharge, it will also employ the Best Technology
Available, in terms of thermal discharge.
3.3.2.6 Thermal Discharge: Cooling Tower Option
The cooling tower option requires a substantially lower flow volume (approximately 2.4%) than
the once-through cooling bounding scenario. Discharge to Lake Ontario from a cooling tower
configuration would employ a diffuser to promote mixing with ambient lake water, thereby
reducing elevated temperatures and development of a thermal plume in the nearshore. The effects
of the thermal discharge on habitat are limited to very moderate water temperature increases in the
immediate area surrounding the diffuser. Since the thermal effects of the once-through bounding
scenario were predicted to be negligible, the considerably lower level of interaction of a cooling
tower configuration with aquatic biota and habitat is also considered to result in only negligible
effects.
3.3.2.7 Lake Infill Structure
The lake infill constructed during the Site Preparation and Construction phase will be a
permanent feature in the nearshore. While habitat loss incurred during construction will be
compensated, lake infills can result in on-going impacts. The Ontario Ministry of Environment
(MOE) (Persaud et al. 2003), identifies potential environmental concerns related to lake infill
structures that include the creation of nuisance conditions where water circulation may be
adversely affected.
Due to the location of the lake infill adjacent to the St Marys Cement site, current patterns in the
nearshore may be altered. These changes may result in reduced water circulation and increased
water temperature at the eastern end of the proposed lake infill. This area also receives inflow
from Darlington Creek that has been noted by SWE to contain higher concentrations of nutrients
in surface water samples from the creek. These conditions may be conducive to enhanced algal
growth possibly to nuisance levels.
Since the effects of the lake infill cannot be predicted in advance with any certainty, and will
depend upon the final configuration of the lake infill, an adaptive management approach will be
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taken to address these concerns. If monitoring indicates that algal growth in this area will be a
problem, then design modifications can be undertaken. These could include further means that
either enhance water circulation to flush nutrients that could contribute to aglal growth, or
alternatively measures to reduce water circulation, favouring the creation of a coastal wetland or
marsh, dominated by vascular plants that would compete with algae for nutrients, thereby
limiting algal growth. Since development along the north shore of Lake Ontario has
systematically reduced the quality and area of these coastal wetland habitats, the creation of
productive new coastal wetland habitat would be a considerable enhancement to the AE. As and
example, creation of a wetland would promote warm water fisheries and waterfowl habitat as a
potential fish habitat compensation plan. Monitoring of the wetland could be incorporated with the
ongoing site biodiversity monitoring plan.
3.3.3 Summary of Effects Advanced for Mitigation
The following Site Preparation and Construction Phase effects were advanced for consideration
of mitigation measures that may be required in addition to the effects management features that
are inherent in the Scope of Project for EA Purposes TSD:
Removal of On-Site Ponds;
Removal of Upper Reaches of Intermittent Tributaries to Darlington Creek;
Alteration/disruption of Coot’s Pond;
Alteration of Upper Reaches of an Intermittent Lake Ontario Tributary;
Lake infill; and,
Construction of Intake and Discharge Structures (including the footprint of the thermal
mixing zone).
The Operation and Maintenance Phase effects of Impingement and Entrainment and Thermal
Discharge have been mitigated by effects management features inherent in the Project design and
have not been advanced for consideration of additional mitigation. However, they are included
below in order to provide a complete summary of both inherent and additional mitigation
measures relevant to AE effects of the Project.
3.4 Consideration of Mitigation and Determination of Likely Residual Effects
Based on the foregoing steps in the assessment process, the interactions between some Project
works and activities and the environment are likely to result in effects on the AE. Adverse
effects were advanced for further consideration of technically and economically feasible
mitigation measures.
Planning for, and application of mitigation measures for environmental effects can take place
both at the time of project planning and design (i.e., as in-design mitigation measures to pre-empt
possible effects); and during the EA process to address those effects identified as likely or
probable during the EA. Both are considered effective means to mitigate the possible adverse
effects associated with a project.
The likely environmental effects of the Project on the AE are described below in Table 3.4-1.
Also included in the table is: i) a description of the applicable features inherent in the Project that
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have been considered in evaluation for their benefit in ameliorating the effects; and, ii) additional
mitigation measures identified during the EA to further diminish or eliminate the likely
environmental effect.
TABLE 3.4-1
Summary of Likely Environmental Effects, In-Design Mitigation Measures and Mitigation
Recommendations
Likely Environmental
Effect
In-Design Mitigation Measures Considered in
the Evaluation
Additional Identified
Mitigation Measures
Access road crossing of
Darlington Creek Sedimentation and erosion controls.
Fish habitat compensation to offset loss of fish
habitat and satisfy requirements of a section
35(2) FA authorization.
Construction of clear span
bridge to avoid in-stream
works.
Re-alignment of access
road to the west to avoid
creek crossing.
Removal of on-site ponds
(Treefrog, Dragonfly and
Polliwog Ponds)
Salvage and re-use/relocation of aquatic plants
and amphibians where practicable.
Additional mitigation not
required.
Removal of Upper
Reaches of Intermittent
Tributaries of Darlington
Creek
Sedimentation and erosion controls to prevent
effects on downstream portions of the tributary
and on the main branch of Darlington Creek.
Site drainage and stormwater management can
maintain contribution of flow within the
Darlington Creek watershed for the north (D2)
tributary.
For the south (E) tributary, site drainage and
stormwater management can contribute flow in a
new channel directed toward Lake Ontario.
Fish habitat compensation, either on-site or off-
site as opportunity allows to offset the loss of
indirect fish habitat and to satisfy requirements
of a section 35(2) FA authorization.
Additional mitigation not
required.
Alteration/disruption of
Coot’s Pond Fish salvage from work areas, depending on
extent of in-water works.
Sedimentation and erosion controls, including
possible settling pond upstream of Coot’s Pond.
Restoration (stabilization, re-planting).
Additional mitigation not
required.
Alteration of Upper
Reaches of Intermittent
Lake Ontario Tributary
Sedimentation and erosion controls
Fish habitat compensation, either on-site or off-
site as opportunity allows to offset the loss of
indirect fish habitat and to satisfy requirements
of a section 35(2) FA authorization.
Additional mitigation not
required.
Lake infill Fish salvage.
Sedimentation and erosion controls.
Fish habitat compensation to offset the loss of
direct fish habitat and to satisfy requirements of
an authorization under section 35(2) of the FA.
Adaptive management
strategy to address
potential nuisance algal
growth. The potential
creation of nuisance algal
growth conditions at the
east end of the lake infill
may require modification
of the design to either
enhance circulation or
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Likely Environmental
Effect
In-Design Mitigation Measures Considered in
the Evaluation
Additional Identified
Mitigation Measures
encourage the development
of a coastal wetland area.
The lake infill will be
monitored, and if nuisance
algal conditions occur,
design modifications may
be implemented where
practicable. As an
example, the development
of a new coastal wetland
area would be a positive
effect on local productivity
and biodiversity,
particularly since there has
been a considerable loss of
these important habitats
since colonial times.
Construction of Intake and
Discharge Structures Siting of the structures in less sensitive habitat
offshore of more productive nearshore habitats
and spawning areas.
Underwater blasting mitigation methods as per
DFO guidance (e.g., seasonal timing restrictions,
fish deterrence, bubble curtains and design of
charge size, placement and sequencing to
minimize incidental mortality) authorization.
Since the project also results in HADD of fish
habitat, the conditions associated with section 32
authorization under the FA will be included
within the section 35(2) authorization.
Fish habitat compensation to offset the loss of
direct fish habitat and to satisfy requirements of
an authorization under section 35(2) of the FA.
The area of the thermal discharge mixing zone
must also be taken into account as a physical
habitat disruption (primarily turbulence, but also
temperature to some extent) and be included in
the fish habitat offsets or compensation
associated with section 35(2) of the FA
authorization.
Additional mitigation not
required.
Impingement and
Entrainment (I&E) The existing DNGS intake structure has been
designed to mitigate entrainment and
impingement mortality and the NND intake
structure will be at least as effective in
minimizing the impingement and entrainment.
Porous veneer intake structure for once-through
cooling (bounding scenario) to minimize intake
velocity.
Location of the intake structure (once-through
bounding and cooling tower scenarios) in less
sensitive habitat offshore of more productive
nearshore habitats and spawning areas.
Cooling tower option will include fish deterrents
Additional mitigation not
required.
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Likely Environmental
Effect
In-Design Mitigation Measures Considered in
the Evaluation
Additional Identified
Mitigation Measures
and/or other mitigation to further reduce I&E
losses.
No SARA/ESA species are expected to be
impinged. If impingement occurs, for example
with American eel, an adaptive management plan
will be used to consider other mitigation
measures.
OPG accepts the obligation under the FA to
provide acceptable and adequate
mitigation/compensation measures for the
potential impacts to fish and fish habitat relating
to the NND Project. The final
mitigation/compensation plan will fulfill the
requirements for an authorization under
section 35(2) of the Act (HADD). The final plan
will also contain components that will address
the requirements under section 32 of the
Fisheries Act (for the destruction of fish by any
means other than fishing).
Thermal Discharge Diffuser discharge structure to limit the size of
the mixing zone and dispersion of a thermal
plume.
Location of the discharge diffuser in less
sensitive habitat offshore of more productive
nearshore habitats and spawning areas.
Additional mitigation not
required.
Considering the likely environmental effects of the Project on the AE and the above-noted
mitigation measures identified to ameliorate the effects, the following residual adverse
environmental effects are anticipated:
3.4.1 Access Road Crossing of Darlington Creek
Construction of the Darlington Creek stream crossing using a box culvert, similar to existing
stream crossings, could result in local habitat destruction. Fish habitat compensation, likely as
part of a comprehensive fish habitat compensation plan for the Project, would be required to
offset the HADD (section 35(2) of the FA).
However, effective mitigation strategies exist such that the crossing could be implemented to
avoid HADD. Instead of using a box culvert, and associated fill within the creek valley, a clear
span bridge could be installed. A bridge would avoid in-stream works and would minimize loss
of riparian habitat within the valley. Alternatively, by aligning the road access to the west of the
creek, the need for a crossing could be avoided altogether. Therefore, with appropriate
mitigation, the construction of an access road would have negligible impact on local aquatic
habitat.
3.4.2 Removal of On-Site Ponds (Treefrog, Dragonfly and Polliwog Ponds)
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As the ponds were constructed features, it is reasonable to suggest that similar habitat could be
constructed elsewhere on the DN site to offset the loss. Where appropriate and practicable,
plants, amphibians and incidental invertebrates salvaged from Treefrog, Dragonfly and Polliwog
Ponds could be introduced to the new facilities to accelerate habitat development. Clearing and
grubbing of the existing ponds would have to be scheduled to coincide with construction of the
SWM pond(s). A disposal area could be designed to retain ponds, or portions of them, within any
geotechnical setback that may be required along the CN line and to replace ponds as part of
constructed site drainage features, which will have to be implemented early in the site clearing
and construction schedule. The result would be a negligible residual effect on aquatic habitat
diversity and biodiversity.
3.4.3 Removal of Upper Reaches of Intermittent Tributaries to Darlington Creek
The on-site portions of the intermittent tributaries to Darlington Creek do not support aquatic
plant, fish and invertebrate species. The sensitivity of the Darlington Creek receiving habitat to
contributions of these tributaries is judged to be low, based on physical and habitat factors in the
main branch of the creek. Nevertheless, it is expected that fish habitat compensation may be
required to offset the loss of the “indirect” or “contributing” fish habitat that will be lost. At the
north (D2) tributary, the conveyance function of the lost portion of tributary could be maintained
by site drainage and SWM features. Habitat function at the north tributary could be improved
over existing conditions (row-crop agricultural) as part of compensation for loss of the original
channel. Although it is unlikely that compensation within the south (E) tributary will be feasible,
improvements to habitat quality and productivity could be incorporated into site drainage
features of the NND station area, or generally addressed as part of a comprehensive fish habitat
compensation plan for the NND Project. The result is negligible residual effect on AE features.
3.4.4 Alteration/Disruption of Coot’s Pond
Coot’s Pond is not well-connected to adjacent aquatic habitat. It is a relatively isolated SWM
pond facility. The extent of alteration or disruption of portions of Coot’s Pond will be kept to a
minimum during the Site Preparation and Construction Phase to protect the existing wetland and
open water habitats. Affected areas could be isolated, if necessary, and fish and other wildlife
transferred to unaffected portions. Restoration of affected Coot’s Pond features will occur
following the Site Preparation and Construction Phase and may include soil/bank stabilization
and replanting of wetland and riparian vegetation. This change is considered negligible in terms
of on-site AE features.
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3.4.5 Alteration of Upper Reaches of Intermittent Lake Ontario Tributary
Changes to the intermittent Lake Ontario tributary near Coot’s Pond are limited in scope to
possible realignment or filling of some reaches to accommodate activities associated with use of
the existing construction waste landfill. Similar to the Darlington Creek tributaries, this
watercourse is assessed as likely constituting only indirect fish habitat in the areas that could be
affected. Mitigation of any adverse effects would likewise be addressed as part of a
comprehensive fish habitat compensation plan for the NND Project, which would offset the
changes with negligible net effect.
3.4.6 Lake Infill
Replacement of 40 hectares of Lake Ontario nearshore habitat with lake fill will affect the
amount of habitat available to VECs on the DN site and, to a lesser degree, Local scales. Direct
mortality associated with lake infill is likely to be limited primarily to benthic invertebrates and
round goby VEC indicator species as they cannot be feasibly salvaged. Other VECs in the fill
area will be salvaged. The primary effect is the loss of habitat for VEC indicator species and
other species. However, granting of a section 35(2) FA authorization by DFO will involve the
design and implementation of appropriate compensation measures that will offset the loss of
habitat. The result is negligible residual effect on AE features, including Lake Ontario nearshore
habitat VEC and the VEC indicator species. Although the lake infill results in no residual effect,
it will be carried forward for significance assesment in the EIS.
The potential creation of nuisance algal growth conditions at the east end of the lake infill may
require modification of the design to either enhance circulation or encourage the development of
a coastal wetland area. The lake infill will be monitored, and if nuisance algal conditions occur,
design modifications may be implemented where practicable. The development of a new coastal
wetland area would be a positive effect on local productivity and biodiversity, particularly since
there has been a considerable loss of these important habitats since colonial times.
3.4.7 Construction of Intake and Discharge Structures
Incidental mortality of limited numbers of individuals of a few VEC indicator species could
occur due to blasting, however this effect is mitigable with measures that can be undertaken in
the blasting program design and specific measures that can reduce the presence of fish in the
blast area or reduce the propagation of harmful shock waves through the water. Underwater
blasting will be subject to DFO authorization under section 32 of the FA (covered within
authorization of section 35(2) of the FA since HADD of fish habitat), and is expected to include
development of mitigation strategies to minimize harmful effects on fish. The residual effect on
VEC indicator species is considered negligible.
The small area of habitat that will be lost in association with the once-through cooling bounding
scenario, including the intake structure site (approximately 1.1 hectares) and discharge diffuser
alignment (approximately 0.7 hectares), will be offset by fish habitat compensation measures that
will accompany a section 35(2) FA authorization. In addition, the area of the diffuser mixing
zone must also be included in the derivation of fish habitat compensation requirements, as it will
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represent a physical disruption of the habitat beyond the installation and presence of the
discharge ports (i.e., turbulence and elevated temperatures in the mixing zone throughout the
Operation and Maintenance Phase). The residual effect on the Lake Ontario nearshore habitat
VECs and the VEC indicator species is considered negligible.
3.4.8 Impingement and Entrainment
As the bounding scenario includes a once-through CCW system at the NND station with a
porous veneer intake structure placed beyond the most productive nearshore areas in at least
10 meters of water, effective mitigation of impingement and entrainment will be achieved
without the need for additional mitigation measures. Small numbers of aquatic organisms will be
impinged or entrained at the NND station, but the residual effect is considered negligible in
terms of population abundance and conservation.
OPG accepts the obligation under the FA to provide acceptable and adequate
mitigation/compensation measures for the potential impacts to fish and fish habitat relating to the
NND Project. The final mitigation/compensation plan will fulfill the requirements for an
authorization under section 35(2) of the Act (HADD). The final plan will also contain
components that will address the requirements under section 32 of the Fisheries Act (for the
destruction of fish by any means other than fishing).
3.4.9 Thermal Discharge
As the bounding scenario includes a once-through CCW system at the NND station with an
offshore discharge diffuser aligned perpendicular to shore in 10 to 15 meters of water, effective
mitigation of thermal effects on the aquatic habitat VECs and VEC indicator species will be
achieved without the need for additional mitigation measures. A relatively small area of Lake
Ontario will serve as a mixing zone beyond which water temperature will be effectively
indistinguishable from ambient conditions. As such, the residual effects on the Lake Ontario
nearshore habitat VEC and the VEC indicator species are considered negligible.
3.5 Potential Consequence of Climate Change on Predicted Effects
Climate change is expected to have some impact on the Aquatic Environment. The potential
consequences of climate change relevant to the predicted effects of the Project on the Aquatic
Environment primarily surround changes to Lake Ontario water temperature and levels (e.g.,
Lake Ontario surface mixed layers expected to increase by approximately 3-5ºC by 2050 due to
warmer air temperatures (Lehman 2002), net basin runoff decreases of 25 to 50% in the Great
Lakes (Environment Canada 1990; CICS 2000); and the subsequent effect on VECs.
Likely effects on VECs as a result of the Project that may be additionally affected by these
potential consequences of climate change are:
increased algae growth and entrapment due to less mixing of the nutrients from
Darlington Creek, warmer temperatures and the protected nature of the embayment;
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localised loss of some VEC species as a result of cooling/service water intake and
discharge structures; and
impingement and entrainment of aquatic biota as a result of once-through lake water
cooling option and the cooling tower option.
As per the discussion presented below, the potential consequences of climate change are not
expected to substantially alter the predictive effects assessment completed for the Aquatic
Environment.
Increased Algae Growth
Potential consequences of climate change include attached algae growth; expected to increase
especially during the early spring periods at the eastern end of the proposed infill in the vicinity
of St. Marys Cement with increased water temperature and decreased water circulation. This
could result in a change in the amount (e.g., larger) biomass of algae becoming detached. The
proposed mitigation for this predicted effect is an adaptive management strategy to address
potential nuisance algae growth for this location. This strategy will include the potential
consequence of a change in amount of algae detachment.
Loss of Species, Impingement and Entrainment of Biota
Reduced flow from the general watershed may cause water levels in Darlington Creek to
decrease. This may result in a lower fisheries productivity of the Creek which would mainly
impact warm water species such as common carp and white sucker. However, at present,
Darlington Creek is not a very productive fisheries tributary.
Water temperature elevations may cause changes to occur in the general fisheries community of
Lake Ontario. There may be a disappearance of some resident species which may be replaced by
other invasive species. Furthermore, fish year class strength and fish community structure is
expected to change with increased temperature. In a review of expected fisheries changes in the
Great Lakes basin due to global warming, Casselman (2002) predicted a decreasing recruitment
of cold and coolwater species (e.g., lake trout, alewife), and increasing relative recruitment of
warmwater species (e.g., smallmouth bass). The proposed mitigation for this predicted effect is
to adapt the design and location of both the proposed diffuser and intake structures accordingly.
It is expected that this mitigation measure will be applicable to a changed fish community
structure and/or species.
3.6 Section 35(2) Proposed Compensation Plan
In accordance with DFO Policy of the Management for Fish Habitat (DFO 1986), with specific
reference to the principle of ‘No Net Loss of the Productive Capacity of Fish Habitat’, OPG
agrees to undertake measures to compensate for and mitigate against, the loss of fish habitat
arising from the New Nuclear at Darlington (NND) Project. OPG has initiated the process by
submitting an Application for Authorization for Works or Undertakings Affecting Fish Habitats
to DFO (September 30, 2009) and will continue to work with DFO to complete the compensation
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plan which will be incorporated into a subsection 35(2) authorization. The final
mitigation/compensation plan will fulfill the requirements for an authorization under section
35(2) of the Act (HADD). The final plan will also contain components that will address the
requirements under section 32 of the Fisheries Act (for the destruction of fish by any means other
than fishing).
OPG in consultation with the DFO, MNR and CLOCA have developed a list of potential options
that may be used to form the compensation plan.
The objectives of the options were determined to be:
1. Favour the target fish species. While both the predator populations and the forage fish
populations have decreased in recent years, the most effective means by which to ensure
the long term survival and increase of all target fish populations of the lake would be to
focus preferentially on increasing the forage base. Options would consider increasing the
predator base.
2. Meet requirements for the area affected by the project that could provide habitat of a
quality necessary to successfully achieve the objectives of the plan.
3. Based on input from Clarington (the host municipality), it is preferred to focus on
potential compensation sites close to the project, preferably within the boundaries of the
Regional Municipality of Clarington.
The potential options identified are provided in Appendix B.
The assessment has concluded that the Project will not result in a residual adverse environmental
effect on Aquatic Habitat because of the mitigation measures that will be implemented.
However, there may be a perception that the loss of aquatic habitat as a result of lake infilling
and the construction of the intake and discharge structures will result in a residual adverse effect,
notwithstanding that mitigation measures will ensure there is no net loss of nearshore aquatic
habitat. For this reason, therefore, the following is advanced for consideration of significance as
if it was, in fact, considered a residual adverse effect:
Loss of approximately 40 ha of Lake Ontario nearshore aquatic habitat as a result of lake
infilling and a further 2 ha (approximately) as a result of construction of cooling water
intake and discharge structures.
3.7 Ecosystem Dynamics –Invasive Species
Invasive species have changed and are continually changing the dynamics of the Great Lakes,
especially in the nearshore environment (State of the Great Lakes Ecosystem 2007). Some of
these changes include the following:
Alewife: A marine invasive species which entered Lake Ontario in the late 1870’s and the upper
Great Lakes much later around 1931 (Scott and Crossman 1998). Alewife is a dominant species
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in the nearshore environment in the SSA and the major species entrained and impinged at DNGS
(see AE Existing Conditions TSD).
Zebra Mussels: First reported in Lake St. Clair in 1988 (Hebert et al. 1989), but were well
established in the Great Lakes in the early 1990’s. Recent benthic and video surveys (2008,
2009) indicated the proliferation of the species along the proposed lake infill shoreline in the
SSA (AE Existing Conditions TSD).
Round Goby: First reported in St. Clair River in 1990 (Jude et al. 2002) and remained confined
to the river until 1993, is now a dominant species in all Great Lakes (e.g. Lederer et al. 2008).
Recent larval fish and fish community studies in the spring of 2009 indicated the importance of
this species in the SSA (see AE Existing Conditions TSD).
Bloody Red Shrimp: First reported in the Canadian side of Lake Ontario in September 2007
(Marty 2007). Results of a 2009 spring survey indicated the presence of this species in the SSA
(first reported case in the vicinity of DNGS, see AE Existing Conditions TSD).
The future is hard to predict but will certainly be changing over time. The near term is not a
prediction of the potential future locally diverse aquatic ecosystem.
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4. REFERENCES
Ager, D.D., Cord, I., and P.H. Patrick 2007. Bay Shore Power Plant Fish Entrainment and Impingement Study Report. Report 112026-005-RA-0001-R00. Kinectrics Inc. Toronto,
Ontario.
Ager, D.D., Cord, I., and P.H. Patrick 2006. Entrainment Sampling At Darlington Nuclear
Generating Station – 2006. Report NK38-REP-07264-10002-R00. Prepared for Ontario
Power Generation Inc.
Ager, D., Cord, I., and P.H. Patrick 2005. Entrainment Sampling At Darlington Nuclear
Generating Station – 2004. Report 070970-001-RA-0001-R00.
The Canadian Institute for Climate Studies (CICS) 2000. Climate Change and Environmental
Assessment, Part 2: Climate Change Guidance for Environmental Assessment, Appendix A - Summary of Projected Regional Climate Change Impacts.
http://www.ceaa.gc.ca/default.asp?lang=En&n=9699932C-1&offset=13&toc=show
Canadian Nuclear Safety Commission (CNSC) 2006. Report On Review of Thermal Mitigation
Technologies for Nuclear Generating Stations, March 2006, Report RSP-0202. Prepared
by Golder Associates, submitted to CNSC, Ottawa ON.
Casselman, J.M. 2002. Effects of temperature, global extremes and climate change on year-class
productivity of warmwater, coolwater and coldwater species in the Great Lakes basin.
American Fish. Soc. Symposium 32: 39-60.
DFO (Fisheries and Oceans Canada). 1986. Policy for the Management of Fish Habitat. Ottawa,
Ontario.
DFO (Fisheries and Oceans Canada). 2007. Ontario Operational Statement – Clear-Span
Bridges. Version 3.0. http://www.dfo-mpo.gc.ca/regions/central/habitat/os-eo/provinces-
territories-territoires/on/pdf/os-eo05_e.pdf
Dunning, D.J., Ross, Q.E., Geoghegan, P., Reichle, J., Menezes, and J. Watson. 1992. Alewives
Avoid High Frequency Sound at a Power Plant Intake on Lake Ontario. North Amer. J.
Fish. Management. 12: 407-416.
Environment Canada 1990. The Climates of Canada, ISSN 0-660-13456-4.
ESG International Inc. 2001. Darlington Nuclear Generating Station Ecological Effects Review.
NK38-REP-0722.07-10001 R000. Ontario Power Generation Inc.
Great Lakes Environmental Center (GLEC). 2007. Impingement Mortality and Entrainment
Study at the Consumers Energy J.H. Campbell Plant. Prepared for Blasland, Bouck and
Lee (BBL) Syracuse, NY.
Griffiths, J.S. 1979. Potential Effects of Unstable Thermal Discharges on Incubation of Lake
Whitefish Eggs. Ontario Hydro Research Divisions Report No. 79-521-K.
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effect
Ontario Power Generation Inc. Technical Support Document
4-2
Griffiths, J.S. 1980. Potential Effects of Unstable Thermal Discharges on Incubating Round
Whitefish Eggs. Ontario Hydro Research Division Report 80-140-K.
Haymes, G.T. and D.P. Kolenosky. 1984. Distribution and Characteristics of Spawning Round
Whitefish in Lake Ontario, 1976-1981. Ontario Fisheries Technical Report Series No. 14.
Ministry of Natural Resources.
Hebert, P.N., Muncaster, B.W. and G.L. Mackie. 1989. Ecological and Genetic Studies on
Dreissena polymorpha (Pallas): A new Mollusc in the Great Lakes. Can. J. Fisheries and
Aquatic Sciences. 46:1587-1591.
Honeyfield, D. 2009. Personal Communication. Scientist, Northern Appalachian Research
Laboratory, Wellsboro, PA.
Hoyle, Jim. 2009. Personal Communication. Assessment Biologist Lake Ontario Management
Unit (LOMU), Ministry of Natural Resources.
Jude, D.J., Reider, R.H. and G.R. Smith 1992. Establishment of Gobiidae in the Great Lakes
basin. Can. J. Fish. Aquatic. Sci. 49: 416-421.
Kissel, R. 1997. Condenser Cooling Water Diffuser Performance. Ontario Hydro Nuclear.
Darlington NGD. Report NK38-REP-07000-003-R00-(P).
Lake Ontario Committee (LOC) 2009. State of Lake Ontario 2008. FMZ Council Presentation.
Lake Ontario Management Unit (LOMU) 2007. 2006 Annual Report of the Lake Ontario
Management Unit. Prepared for the 2007 Combined Upper and Lower Great Lakes
Committee Meetings, Great Lakes Fishery Commission. Queen’s Printer for Ontario,
Picton, ON.
Lederer, M., Janssen, J., Reed, T. and A. Wolf. 2008. Impacts of the Introduced Round Goby
(Apollonia melanostoma) on Dreissenids (Dreissena polymorpha and Dreissena
bugensis) and on Macroinvertebrate Community between 2003 and 2006 in the Littoral
Zone of Green Bay, Lake Michigan. J. Great Lakes Res. 34:690-697.
Lehman, J, 2002. Mixing Patterns and Plankton Biomass of the St. Lawrence Great Lakes under
Climate Change Scenarios. J. Great Lakes Res. 28(4): 583-596, International Association
of Great Lakes Research.
Maher, J.F.B. 1980. Location of the Darlington GS Cooling Water Intake With Respect to the
Distribution of Aquatic Biota.
Marty, Jérôme. (2007) Biological Synopsis of the Bloody Red Shrimp (Hemimysis anomala).Can. MS Rpt. Fish. Aquat. Sci. Draft. 36p.
Minns, C.K., Meisner, J.D., Moore, J.E., Greig, L.A. and R.G. Randall. 1995. Defensible
Methods for Pre- and Post-Development Assessment of Fish Habitat in the Great Lakes.
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effect
Ontario Power Generation Inc. Technical Support Document
4-3
I. A Prototype Methodology for Headlands and Offshore Structures. CanadianManuscript Report of Fisheries and Aquatic Sciences. 2328 (1995): xiii+65 p.
Minns, C.K. Quantifying “No Net Loss” of Productivity of Fish Habitats. Canadian Journal of
Fisheries and Aquatic Sciences. 54 (1997): 2463-2473.
Minns, C.K., Moore, J.E., Stoneman, M. and B. Cudmore-Vokey. Defensible Methods of
Assessing Fish Habitat: Lacustrine Habitats in the Great Lakes Basin – Conceptual Basis and Approach Using Habitat Suitability Matrix (HSM) Method. Canadian Manuscript
Report of Fisheries and Aquatic Sciences. 2559 (2001): viii+70 p.
Normandeau Associates, Inc. 2007. Section 316(b), Phase II Fish Impingement Mortality and
Entrainment Characterization Study at the Donald C. Cook Nuclear Plant. Prepared for
American Electric Power Bridgman, MI.
Owen, R.W., O’Gorman, R. and S.R. LaPan. 2003. Status of Major Prey Fish Stocks in the US
Waters of Lake Ontario. NYSDEC Lake Ontario Report.
Patrick, P.H., and S. Rkman-Filipovic 2004. Space Perception of Fish in Reference to WE’s
Proposed Porous Dike Concept. Kinectrics Report No. K-010259-001-RA-0010-R00.
September.
Patrick, P.H. and S. Poulton 1993. Effectiveness of the Porous Veneer Intake at Excluding Fish
at Darlington – Sonar and Video Evaluations 1993. Report NK38-07000-T10.
Persaud, D.,, Hayton, A., Jaagumagi, R. and G. Rutherford. 2003. Fill Quality Guidelines for
Lakefilling in Ontario. Ont. Ministry of the Environment Report. ISBN 0-7729-9329-7.
March 2003.
Romanchuk, M.E. and W.L. Burchat 1997. Thermal Plume Study – Darlington NGD – Lake
Ontario – 1990-1996. Report: R-NK38-02740-0003.
Scott, W. B. and E. J. Crossman. 1998 (Editors). Freshwater Fishes of Canada. Galt Mouse
Publication, Oakville. ON. 966 p.
SENES Consultants Ltd. 2009. Biological Liability Losses of Environmental and Impinged Fish
at the Intake Structure of Darlington Nuclear Generating Station. NK54-REP-07730-
00031.
SPDES Biological Monitoring Report 2004. James A. FitzPatrick Nuclear Power Plant (Permit
No. NY 0020109, Section 10, CP-04.03). May 2005.
State of the Great Lakes Ecosystems 2007. Environment Canada and United States
Environmental Protection Agency. EPA 905-R-07-003.
Tarandus Associates Limited (Tarandus) 1996. 1995 Aquatic Monitoring Studies At The
Darlington NGS. Data Report NK38-07015-6. Prepared for Ontario Hydro.
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effect
Ontario Power Generation Inc. Technical Support Document
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Tarandus. 1998. The Evaluation of fish Communities in Armoured and Natural Habitats in the
Vicinity of the DNGS. OPG Report NK38-REP-07000-016-ROO.
Wismer, D.A. 1997a. Condenser Cooling Water Intake Performance. Ontario Hydro Nuclear.
Report No. NK38-REP-07000-006-R00-(P).
Wismer, D.A. 1997b. Condenser Cooling Water Intake Fish Impingement Monitoring Sampling
Verification. Report NK38-REP-07000-013-R00. Ontario Hydro.
Wismer, D.A. and A.E. Christie 1987. Temperature Relationships of Great Lakes Fishes – A
Data Compilation. Great Lakes Fishery Commission, Ann Arbor, MI.
Wright, D.G., and G.E. Hopky 1998. Guidelines for the use of explosives in or near Canadian
fisheries waters. Can. Tech. Rep. Fish. Aquat. Sci. 2107: iv + 34p.
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APPENDIX A
NEW NUCLEAR - DARLINGTON - EA BASIS TABLE
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New Nuclear - Darlington - Basis for EA
Project Phase / Works
and Activities
Description
Site Preparation Phase
Mobilization and
Preparatory Works
Mobilization (construction workforce and equipment): will involve mobilization of equipment and the construction workforce to the site. The
physical aspects of mobilization will involve the establishment of parking areas for staff and equipment, service areas for construction offices,
construction phase fencing for security and safety and equipment storage; security/guardhouse and reception facilities.
Clearing and Grubbing: Vegetation within areas of future construction will be removed. A variety of methods including the removal of trees by
truck, chipping of smaller vegetation and grubbing with a dozer or excavator will be used to remove vegetation. Environmental effects
management measures will be applied throughout the activity such as minimizing the area to be cleared to the extent feasible and complying with
seasonal constraints and regulatory requirements for clearing operations.
Installation of Services and Utilities: includes temporary services and utilities required during construction and permanent services and utilities
required to support operations. Wherever possible, utilities and services will be installed to accommodate the needs of both construction and
operation phases. Utilities and services will include: i) potable water; ii) sanitary sewage collection discharging to a municipal water pollution
control plant; iii) electrical and telephone service; iv) P.A. system; v) fencing. Excavation to install services is captured by other earthmoving
activities.
Development of Roads and Related Infrastructure: includes improvements to access into the site and features to provide for temporary (i.e.,
during construction) and permanent (during operations) access, egress and parking. Onsite roads and infrastructure will include local access roads
and parking facilities within the site to accommodate workforce-related and other traffic during both construction and operation phases. For EA
purposes, it is assumed that off-site parking facilities may be used with workers transferred to the NND via shuttle bus.
Excavation and Grading Excavation and grading will comprise all earth and rock-moving activities including earthmoving and grading, drilling and blasting. Excavation
activities will be conducted in-the-dry with dewatering where required. Collected water will be managed and discharged as described in
Management of Stormwater.
On-Land Earthmoving and Grading: During site preparation activities, effectively all land area east of Holt Road will be disturbed to a large
extent. Topsoil stripping will be by means of suitable earthmoving equipment (e.g., scrapers, excavators and trucks). Excavated soils transferred
to the Northeast and Northwest Landfill Areas and lake infill will be placed using good management practices that address surface erosion, dust
control and related aspects including noise and vehicle emissions.
Transport of Surplus Soil to Off-site Disposal: Should it be necessary to do so, surplus soil will be transported to disposal at an off-site
location(s). The destinations for this material have not been determined, however, it is intended that the material be used to rehabilitate extraction
pits and quarries or other development sites, or similar beneficial use.
Rock Excavation and Grading (Drilling, Blasting, Boring): will involve the excavation and grading of rock and like material, and associated
activities such as drilling or blasting to facilitate its excavation and transfer to rock fill areas (i.e. lake infill) or disposal areas.
Development of Construction Laydown Areas: will include specific areas identified for, and developed as, staging areas for contractor
operations and storage areas for construction equipment and materials. Laydown areas will be graded, temporarily fenced, and surfaced,
depending on function, with granular or asphalt.
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Project Phase / Works
and Activities
Description
Marine and Shoreline
WorksMarine and Shoreline Works includes all works and activities conducted within or adjacent to Lake Ontario such that they are likely to interact
with the marine and aquatic environment. Marine and shoreline-related works and activities will include the following:
Lake infill and Shoreline Protection: will occur throughout an area of Lake Ontario and will extend from the easterly limit of the DN site to
approximately the DNGS intake channel; and about 100 m into the lake on its westerly limit to approximately 450 m on its easterly limit. Lake
infill will create a new landform of up to approximately 40 ha. The lake infill operation will begin with the construction of a low-permeability
coffer dam on its outer perimeter to contain the deposit lake infill materials and isolate the area from lake water intrusion. The core would
typically consist of low-permeability soils or compacted granular materials, driven or vibrated steel sheeting, or drilled caissons. The lake-facing
surface of the dam will be covered with armour stone placed by crane on the lake side of the dam. Any fish within the area to be dammed will be
directed out of the work area by progressive seining and other appropriate means as the dam is placed. Once the cofferdam is complete, the water
contained within it will be pumped out and discharged to Lake Ontario. The material placed within the cofferdam to create the new landform will
originate on-site and be placed as part of the Excavation and Grading activity.
Construction of Wharf: a wharf will be developed in a portion of the lake infilled area generally in front of the Power Block. The wharf will be
used during construction for off-loading oversize and over-weight components and its construction will be appropriate for this purpose.
Lake Bottom Dredging: dredging activities are expected to be minimal, but may be required at the point where the cooling water intake tunnel
daylights to the lake bottom. Any such minor dredging will involve conventional equipment designed and operated for the purpose (suction and/or
mechanical). All dredged sediment will be placed into barges and subsequently off-loaded and disposed of in the Northeast Landfill Area or
existing onsite construction landfill.
Development of
Administration and
Physical Support
Facilities
Administration and Support Facilities comprise various buildings housing staff, equipment and operations necessary to provide ongoing support to
the NND. These will include offices, workshops, maintenance, storage and perimeter security buildings, and utilities operating centres. All such
buildings will consist of conventional steel and masonry structures.
Construction Phase
For assessment purposes, it is assumed that the entire site will be prepared for construction at the outset. Construction of the nuclear power plant elements (i.e., construction
phase) will begin as soon as possible into the site preparation activities and accordingly, the site preparation and construction phases will overlap in time. This is a bounding
assumption since it represents the greatest amount of related work in the shortest period of time.
Construction of Power
BlockThe Power Block includes the reactor building, the turbine-generator building/turbine hall (powerhouse) and related structural features that are
physically associated with them. Development of the Power Block includes the installation of all power generation equipment within it, including
the reactors, primary and secondary heat transport components, and all powerhouse components including turbines, generators and heat
exchangers and pumps and standby power systems. Supply of construction materials and operating equipment to the site is included in the
Construction Material and Operating Equipment Supply.
Foundations will extend into bedrock and may require drilling and blasting. Some elements of construction will be further supported on steel piles.
Above-grade construction will involve techniques typical of heavy industrial development. Placement will involve extensive use of heavy
equipment, including heavy-lift fixed and mobile cranes. Installation of operating equipment will involve movement and placement of large and
specialty components using various standard and extraordinary procedures, depending on the size and weight of the component.
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Construction of Intake
and Discharge Structures Intake and Discharge Tunnels and Structures for Once-Through Lake Water Cooling: For EA purposes, the once-through cooling water
intake and diffuser structures at NND are assumed to be similar to the existing structures at DNGS, although appropriately sized to accommodate
the required water flow rates at NND. The tunnels at DNGS were constructed using typical underground mining techniques involving blasting and
excavation. Tunnels for once through cooling water at NND may alternatively be constructed by boring using a purpose-built tunnel boring
machine (TBM).
Intake and Discharge Structures for Cooling Tower Water Makeup and Service Water: Although the water from both mechanical draft and
natural draft cooling towers is recirculated, some make-up water is required to replace tower blowdown and other losses (e.g., evaporation) and for
plant service water needs. This water will be drawn from Lake Ontario via intake and discharge pipelines. The open-cut drill-and-blast method is
likely to be used to excavate a trench to place the intake or outfall pipe. Pipes will be placed in trenches and backfilled with a granular material,
and armour surface protection. Screens may be used to prevent debris from entering the intake structure. Both the intake and discharge structures
for makeup water and service water will be substantially smaller than those required for once-through lakewater cooling due to the smaller
associated water volumes.
Construction of Ancillary
Facilities Ancillary facilities include all features necessary to support operations of the reactors and generation of electricity, although not physically
associated with the power block. Clearing and grubbing and major earthmoving and grading to accommodate development of the ancillary
features are included in the Mobilization and Preparatory Works, and the Earthmoving and Grading activities, respectively.
Expansion of Existing Switchyard: will involve the physical enlargement of the footprint of the existing DNGS switchyard, an increase to the
electrical capacity to accommodate its use for NND, and its connection to the existing electrical grid. The switchyard expansion will effectively be
as an easterly extension to the existing switchyard.
Cooling Towers – Mechanical Draft: includes the towers and the associated infrastructure to support their operation. Mechanical draft cooling
towers are typically shorter in height and larger in footprint than natural draft cooling towers. Construction of the towers will involve conventional
techniques and materials, primarily steel framing, concrete and masonry, and mechanical and electrical components.
Cooling Towers – Natural Draft: includes the towers and associated infrastructure to support their operations. Up to two natural draft towers
may be constructed for each unit (depending on the design). The towers will have a hyperbolic shape. The towers will be constructed of steel
reinforced concrete with structural, mechanical and electrical components and will be erected by means of traditional construction methods (e.g.,
slip forming, crane lifts), and conventional construction materials.
Cooling Towers – Fan Assisted Natural Draft: are not included in any of the three model plant layout scenarios considered in the EA. Because
they are a variation of the two cooling tower types that are considered, their potential interfaces with the environment during construction are
considered to be bounded by the cooling tower options that are addressed in the EA. Fan assisted natural draft cooling towers have a slightly
larger base dimension than the natural draft cooling tower, and have fans placed around the base of the tower to increase the air flow rate. These
towers have a similar hyperbolic shape as a traditional natural draft tower, but approximately the height.
Cooling Tower Blowdown Ponds: For each of the cooling tower options one or more blowdown ponds may be required to receive and treat
blowdown from the towers. Blowdown is the portion of the circulating water flow that is removed in order to maintain the amount of dissolved
solids and other impurities at acceptable levels. The ponds would be excavated into the ground surface and lined (e.g., with clay or synthetic
materials) to ensure proper containment. The ponds will be sized to accommodate the required volume for the system, and the water would be
appropriately treated to comply with discharge water quality criteria, prior to discharge.
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Construction of
Radioactive Waste
Storage Facilities
Radioactive Waste Storage Facilities comprise used fuel dry storage facility to house containerized used fuel bundles following their removal from
wet storage in the used fuel bays. Low and Intermediate Level Waste Storage building(s) may also be required. For EA purposes, it is assumed
that a used fuel dry storage building for NND will not be required until approximately 2025, though a storage building for Low and Intermediate
Level Waste will likely be required starting in 2017.
Common to Site Preparation and Construction – Works and Activities
Management of
Stormwater As the site is developed, ditches and swales will be constructed to collect and convey surface water to stormwater management ponds and
ultimately to discharge to an existing drainage course or Lake Ontario. Stormwater management features will be developed to address the
requirements for runoff control both during site preparation and construction (temporary) and during operations (permanent). Wherever possible,
stormwater management features will consider the needs of both construction and operation phases.
Supply of Construction
Equipment, Material and
Operating Plant
Components
Supply of construction materials and operating equipment includes the delivery to the site, of all necessary materials and components for
construction of NND. While much of the material that will be delivered to the site will be via the road network, large components may be
delivered by rail (to an existing rail siding on a neighbouring property and then transported overland to the site or to a new rail siding on the DN
site), or by barge to the new wharf.
Rock Delivery for Cofferdam: delivery of imported rock for cofferdam construction is estimated to be up to 200 trucks per day.
Construction Equipment: comprises all mechanized and related equipment required to support construction. Heavy earthmoving equipment will
be typical of large-scale construction projects (e.g., trucks, dozers, loaders, excavators, scrappers, graders, compactors).
Aggregate and Concrete: For EA purposes, it is assumed that ready-mixed concrete will be provided by an offsite supplier operating on a nearby
property, or is mixed on site in a concrete batch plant. Approximately 750,000 to 1,000,000 m3 of concrete will be required for 4 units.
Manufactured Construction Materials: will include items associated with site preparation (e.g., precast concrete structures, culverts and utility
piping, fence), structural components for buildings and other facilities (e.g., fabricated steel products, masonry), mechanical and electrical
components for buildings and facilities, and various sundry items (e.g., interior finish components). All manufactured construction materials will
be delivered to the site via highway-licensed trucks travelling on provincial and municipal roads, by rail, or by barge. Aside from concrete, the
largest single quantity of material that will be delivered to the site will be structural steel (rebar etc). Approximately 150,000-200,000 tonnes of
structural steel would be required for 4 units.
Plant Operating Components: are fixtures and components associated with an operating nuclear plant. These will include conventional items
(e.g., pumps, turbines, electrical power systems) as well as those that are unique to nuclear plants (e.g., calandria). Most operating components
will be delivered to the site via highway-licensed trucks travelling on provincial and municipal roads. Some oversize items will require special
permits and transport provisions, and others are likely to be transported to the site by rail or via barge and off-loaded at the purpose built wharf.
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Management of
Construction Waste,
Hazardous Materials,
Fuels and Lubricants
Construction waste: will be transferred from the site to disposal or recycling at appropriately-licensed waste management facilities. This activity
does not include disposal of excavated spoil (see Excavation and Grading). The existing on-site DNGS construction landfill may also be reopened
for the disposal of construction waste.
Hazardous Materials: (e.g., solvents, chemicals, compressed gases) associated with site preparation and construction will be managed, including
storage, use and disposal, in compliance with applicable legislation, codes and practices. These materials will include expired chemicals, cleaners,
paint, aerosol cans and electrical components. Non-radioactive oil and chemical wastes will be removed from the site for disposal.
Fuels, Lubricants and Chemicals: those required for mechanical construction equipment will be delivered to the site in appropriately-qualified
vehicles and/or containers, stored in purpose-built facilities, and dispensed and used, all in compliance with applicable legislation, codes and
practices. Contingency plans for a detailed response system in the event of a spill will be developed.
Work Force, Payroll and
PurchasingSite preparation and construction will require a contractor labour force that will vary in size throughout the work based on the scope and nature of
the activities underway at any given time. This activity will represent the daily transportation-related aspects of workforce commute as well as the
economic aspects associated with payroll and construction-related capital purchases. The labour force will peak, in the early years of the Project,
at approximately 3,800. In later years of the site preparation and construction phase, the workforce involved in the construction of units 3 and 4
will overlap with staff operating units 1 and 2 and will peak at approximately 5,200.
Operation and Maintenance Phase
Prior to the start of the Operation and Maintenance Phase, commissioning activities will be undertaken including the testing of systems and components. Nuclear fission
reactions in the reactor core will be increased in a controlled manner until criticality is achieved. Reactor power will then be increased in a controlled manner. Steam will be
admitted into the turbine and the steam and feedwater system will be placed into service. The unit’s electrical generator will be connected, or synchronized, to the electrical grid.
Maintenance, both routine and major, is included in this phase of the Project. Three general areas of maintenance are performed: preventative maintenance, corrective
maintenance, and improvement or upgrade activities (including during planned shutdowns and outages).
Operation of Reactor
Core
The reactor consists of the reactor assembly and reactivity control devices. The reactor core is the starting point for the generation of radioactivity.
All other systems in the nuclear power plant (NPP) work to support the reactor core. This activity includes operation, startup, shutdown, and
maintenance, testing and modification of the reactor core components, including the maintenance required for refurbishment. Nuclear malfunction
and accident considerations will originate here.
In an ACR-1000 reactor the horizontal calandria vessel is axially penetrated by calandria tubes. The calandria tubes provide access through the
calandria vessel to the fuel channel assemblies containing nuclear fuel bundles of varying fuel enrichments.
In the EPR and AP1000 reactors, a pressure vessel contains vertically oriented assemblies of fuel rods called fuel assemblies. The assemblies,
containing various fuel enrichments, are configured into the core arrangement located and supported by the reactor internals. The reactor internals
also direct the flow of the coolant past the fuel rods.
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Operation of Primary
Heat Transport System
The function of the primary heat transport system is to move heat from the reactor core into the primary side of the steam generator. This system
will generate L&ILW (such as filters and ion exchange resins). This is captured in the Waste Management work activity. Maintenance of this
system includes periodic chemical cleaning of the steam generators and replacement of parts during refurbishment and is included in the Major
Maintenance work activity. Water losses are captured under the ventilation and drainage project works and activities. For all of the technologies,
the chemistry of the reactor coolant is controlled by filtering, ion exchange, and chemical addition.
In an EPR reactor, core cooling and moderation are provided by light water (H20) at high pressure. There is no separate moderator system, only a
reactor coolant system. The coolant is circulated through 4 cooling loops, each containing a steam generator. A pressurizer and a chemical and
volume control system are used to maintain inventory and chemical composition in the reactor coolant system. The coolant used in this system
contains boron, which acts as a neutron absorber and can also result in a reaction that forms tritium in the heat transport system fluid.
Unique to the AP1000 reactor is the use of 2 cooling loops instead of 4, and therefore the use of only two steam generators. The remainder of the
system is similar to that of the EPR reactor.
In an ACR-1000 reactor, the heat transport system circulates light water through the reactor fuel channels to remove the heat produced by the
fission of uranium fuel within the fuel bundles. Coolant from the fuel channels passes to the four steam generators where the heat is transferred to
the secondary side to generate steam.
The ACR-1000 reactor has a calandria filled with a heavy water (D2O) moderator. The moderator slows down neutrons from fission reactions in
the fuel, increasing the opportunity for these neutrons to trigger additional fissions. The heavy water moderator is circulated and cooled. This
system is separate from the primary heat transport system, and is a low pressure, low temperature closed circuit. This activity includes routine
maintenance of the moderator systems and their auxiliaries.
Heavy water management is only applicable to the ACR-1000. Heavy water is managed during maintenance activities and those activities
connected to the movement of heavy water inventories into and out of the moderator system. Heavy water is managed in the ACR-1000 by the
D2O Supply System, the D2O Vapour Recovery System and the D2O Cleanup System.
Measures are taken to minimize the loss and downgrading of the heavy water, which escapes from the moderator systems. Heavy water may be
transported offsite to a licensed facility for the removal of tritium.
Losses from the heavy water management system are addressed under the active ventilation systems and radioactive liquid waste management
activities.
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Operation of Active
Ventilation and
Radioactive Liquid
Waste Management
Systems
Radioactive Liquid Waste Management: The active drainage system segregates liquid waste by the degree of contamination and directs it to the
receiving tanks of the radioactive liquid waste management system. The system discharges treated wastes at a controlled rate to Lake Ontario after
stringent testing and treatment to maintain acceptable activity levels for release.
Tritium can be found in heavy water after contact with the reactor core, and this may be present in waterborne and airborne emissions from water
losses. There are cleanup (ion exchange columns and filters) and upgrading facilities for recovered heavy water that will be used if heavy water is
present in the liquid waste stream. There are also heavy water vapour recovery circuits in each reactor building to dry the atmosphere in areas that
are subject to heavy water leakage during operation or servicing of equipment.
Tritium can also be produced through neutron capture by B-10 in the EPR and AP1000 reactors. This tritium can be found in liquid and airborne
effluents due to water losses.
Radioactive Gaseous Waste Management: Gaseous wastes from potentially active areas, such as reactor buildings, will be monitored for
activity before release to the atmosphere. The gases from the active ventilation stacks are filtered through absolute and charcoal filters before
being released, to minimize the release of radioactivity. In some cases, the release of active gaseous waste is delayed to allow for decay of short-
lived radioisotopes.
Operation of Safety and
Related Systems
A multiple barrier approach has been built into the design of all of the reactors to control releases of radioactivity to the environment.
The ACR-1000 reactor has five safety systems: Shutdown System 1 (SDS1) and Shutdown System 2 (SDS2), which provide emergency safe
shutdown capability for the reactors, the Emergency Core Cooling System (ECCS), the Emergency Feedwater System (EFW) and the Containment
System.
The EPR reactor design includes four safety systems: the Safety Injection System (SIS) which provides emergency cooling, the Rod Cluster
Control Assembly (RCCA) shutdown system which provides rapid reactor shutdown, the Emergency Feedwater System (EFWS), as well as the
Containment System.
The AP1000 reactor includes four safety systems: the Passive Core Cooling System (PXS) which is designed to provide emergency core cooling;
the Passive Containment Cooling System (PCS) which provides for the removal of heat from the containment vessel using water and airflow; the
Containment System which is a steel vessel surrounded by a concrete shielding structure; and the Reactor Trip System, which acts to keep the
reactor operating away from any safety limit.
Fuel and Fuel Handling includes receipt, handling and storage of fresh fuel and used fuel.
Fuel: The reactor may be fuelled with low enriched uranium (LEU) or more highly enriched uranium, with a maximum enrichment of
approximately 5% U-235. The enrichment level and configuration of the fuel differs based on the reactor class. Fuel will be delivered to the NND
site in protective flame retardant containers and stored in these containers until required. Criticality safety is a concern due to the enrichment of the
fuel and a criticality program will be put in place to mitigate this.
Fuel Storage and Handling: The fuel handling system comprises equipment required for fuel changing, for the storage of fresh fuel, and for on-
site storage of used fuel.
Operation of Fuel and
Fuel Handling Systems
New fuel storage: New fuel is stored in a high density rack which includes integral neutron absorbing material to maintain the required degree of
subcriticality. The rack is designed to store fuel of the maximum design basis enrichment.
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Fuelling system: In the ACR-1000 reactor, fuelling of the reactor is completed online. Fresh fuel bundles are pushed into one end of the fuel
channel by a remotely operated fuelling machine. Irradiated fuel bundles are simultaneously discharged at the other end of the channel into
another fuelling machine.
For the EPR and AP1000 reactors, fuelling must be completed during a refuelling outage. The refuelling operation is divided into four major
phases: preparation, reactor disassembly, fuel handling, and reactor assembly. Prior to refuelling, the reactor pressure vessel (RPV) cavity is
flooded with borated water and the reactor internals are placed in an internals storage pool separated from the reactor cavity by a removable gate.
Fuel assemblies are remotely removed from the RPV and sent to the Spent Fuel Pool (SFP) through the fuel transfer tube. Some new fuel
assemblies may be stored in the SFP, from where they will move through the fuel transfer tube and be placed into the RPV by the refuelling
machine. When the refuelling is complete, the RPV internals are replaced into the RPV, instrumentation, and control/shutdown rods are
reconnected, and the reactor vessel head is placed and fastened back onto the RPV. The borated water is then drained from the refuelling work
areas and can be reused in the IRWST.
Used Fuel Handling: In every reactor technology, the used fuel storage facility will be composed of transfer systems that carry the used fuel from
the reactor to a used fuel storage pool in which the fuel is stored and cooled. The used fuel will be stored in a used fuel storage bay until it has
cooled sufficiently for storage using an alternative means.
Used Fuel Bay and Auxiliaries: The design specifications and location of the used fuel storage pool will be determined based on the reactor
technology selected and the level of enrichment of the fuel to be used. Neutron absorbing material and spacers will be used to maintain the desired
degree of subcriticality. A fuel bay cooling and purification system is used to maintain chemical composition, volume, activity level and
temperature of the water in the fuel bay at desired levels. Filters, ion exchange columns and heat exchangers may be used depending on the
specific reactor design selected.
Turbine/Generator and Auxiliaries comprise the turbine/generator, steam supply, main condenser, feedwater heating system and auxiliary
systems. These systems are similar for the EPR, AP1000 and ACR-1000 reactors. This system also includes the generator oil supply and the
associated fire suppression systems. This activity also includes maintenance of the system components. Interactions with the environment resulting
from this activity are from oil leaks and water usage.
Turbine/Generator System: Each unit has one turbine/generator unit and its auxiliary systems. The EPR and ACR-1000 reactors have four
steam generators, and the AP1000 has two.
Steam Supply: Steam is produced in steam generators in the reactor building, and transported by pipes to each turbine/generator. The specific
configuration may vary by reactor design.
Main Condenser: Steam from the turbines exhausts into the condenser shells where it is condensed using Condenser Circulating Water and
collected in the hotwells. The condensate feedwater system collects the condensed steam from the turbine and supplies it to the steam generators.
External makeup to the closed loop steam and feedwater system is from the demineralized water storage tank. This configuration is independent of
reactor technology selected.
Operation of Secondary
Heat Transport System
and Turbine Generators
Feedwater Heating System: The feedwater heating system supplies feedwater to the steam generators where applicable, preheats the water to
achieve a good heat rate, and performs several other functions. This is generally true for all reactor technologies.
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Auxiliary Systems: The major turbine/generator auxiliary systems are: the sampling system, which permits sampling steam and feedwater for
chemical analysis; and the chemical control system, which eliminates the residual oxygen from the deaerated feedwater and controls its pH. These
systems have different names depending on which reactor is being discussed but perform the same functions.
Operation of Condenser
and Condenser
Circulating Water,
Service Water and
Cooling Systems
The condenser circulating water system (CCW) supplies cold water to the condenser tubes to condense the steam from the turbine exhaust. Four
options are being assessed for the CCW system. These options are: once through cooling water, natural or mechanical draft cooling towers, or fan
assisted natural draft cooling towers. Dependent on climate and land considerations, a combination of these technologies may be used to provide
condenser circulating water at NND.
The once-through CCW system draws water from Lake Ontario, pumps the water through the condenser tubes, and discharges the water back to
Lake Ontario. Water will be brought into the plant through a lake bottom intake tunnel. The configuration of the intake tunnel and structure will be
similar to that currently being used at DNGS, but sized to the necessary water volumes.
Natural draft cooling towers are taller and have a smaller footprint than mechanical draft cooling towers, and up to two towers will be required for
each reactor unit. A natural draft tower uses convection and evaporation forces to cool the condenser circulating water.
Mechanical draft cooling towers use power driven fan motors to force or draw air through the tower. They are typically shorter and have a larger
footprint than natural draft cooling towers.
For both cooling tower technologies, makeup condenser cooling water is drawn from Lake Ontario at significantly lower rates than with once
through cooling, however, a portion of the water is lost to evaporation. The blowdown flow is directed to blowdown ponds, where mineral and
particulate impurities may be removed. Discharge will comply with appropriate criteria for surface water discharge to Lake Ontario.
Service Water Systems: Water will be drawn from Lake Ontario and distributed to the various systems. For the once-through cooling option,
service water will be combined with the CCW systems intake. For the cooling tower option, service water is drawn from the CCW closed loop
circuit.
Demineralized Water: NND will include two demineralized water plants to remove minerals removed from lake water prior to use in plant
cooling systems.
Inactive Drainage Systems: The inactive drainage system collects wastewater in various buildings (turbine building, waste treatment building,
pumphouses etc.). The wastewater is collected and treated as required to comply with discharge criteria prior to discharge.
Electrical Power Systems deliver power to and from the grid, generate emergency power and distribute power throughout the station. The
Electrical Power Systems will be similar for all reactor technologies as their operation is independent of the reactor itself. Possible environmental
interactions may include noise, spills or leaks from storage tanks, and air emissions from the generators.
Switchyard and Main Transformers: A switchyard is located near the station to connect the station to the grid transmission lines. The main
transformers and associated service transformers are oil cooled.
On-Site Power System: Power used internally at DNGS is supplied both from the unit itself and from the grid. Several buildings largely used for
administration or general support functions are supplied with electricity from the grid.
Operation of Electrical
Power Systems
Generation of Emergency and Standby Power: On-site standby diesel generators (DGs) provide back-up power sources to specific station
loads. The configuration of the diesel generators is similar for all reactor technologies.
Operation of Site Domestic Water: The domestic water system will be supplied from Durham Region water mains.
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Sewage System: The sewage system collects waste throughout the complex and discharges it into the Regional Municipality of Durham sewage
mains.
Stormwater Management: Stormwater management features will be developed to address the requirements for runoff control. Stormwater runoff
ponds will be sufficient in number and size to provide adequate retention times following rainfall events. The pond design will incorporate an
emergency overflow bypass for flows in excess of the design storage capacity.
Compressed Air: The compressed air systems consist of instrument air, service air, high pressure air and breathing air.
Heating and Ventilation: The heating and ventilation systems are required to provide comfort to people working inside the plant and prevent
equipment and line freezing during plant shutdown in the winter. Steam, electricity, and hot water are used for heating.
On-Site Transportation: There is an extensive existing road network at the DN site including the roadways and parking lots necessary to service
DNGS. Further infrastructure will be developed to service NND. The roads are used by employees, contractors and visitors to drive to and from
the site, as well as for the transfer of materials.
Services and Utilities
Other Auxiliary Systems: Other auxiliary systems will include: communication systems; lighting systems, site security facilities, auxiliary and
service buildings, and fencing. NND will also have a dedicated onsite laundry facility.
Management of
Operational Low and
Intermediate-Level
Waste
Management of Low and Intermediate-Level Waste (L&ILW) will be similar regardless of reactor design selected. Two options for management
of L&ILW include storage in a modular building on the DN site, and transport to an appropriately licensed facility off-site. Low Level Storage
Buildings (LLSB), constructed as required, could accommodate both Low and Intermediate Level Waste. Eventually, the waste would be
transported to an appropriate facility off-site for long-term management. The first LLSB will be required by approximately 2017.
Transportation of
Operational Low and
Intermediate-Level
Waste to a Licensed Off-
site Facility
Transportation of L&ILW to the WWMF or another licensed facility and transportation of other radioactive materials, such as tritiated heavy
water, will be carried out in accordance with the NSCA and its Regulations and other applicable regulations (e.g., as made under the
Transportation of Dangerous Goods Act).
Dry Storage of Used Fuel Used fuel from NND will be stored in used fuel bays for approximately ten years following removal from the reactor. After this cooling period,
the fuel is moved to dry storage containers which are processed and stored in a Used Fuel Dry Storage (UFDS) Building. Storage containers differ
between the ACR and the two PWR reactors due to differences in fuel characteristics. UFDS buildings will be constructed as required, and will be
either an independent facility of an expansion to the existing DWMF.
Management of
Conventional Waste
The generation of non-radioactive wastes will be minimized to the extent practicable through re-use and recycling programs. All residual waste
will be collected regularly by licensed contractors and transferred to appropriately licensed off-site disposal facilities. Hazardous wastes will be
handled in accordance with applicable regulations.
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Major Maintenance: Some systems and components will require maintenance, replacement or upgrading. A maintenance program for the plant
will be developed to address issues related to ageing, wear and degradation. A portion of this work will require the unit to be offline for these
maintenance activities to be completed. Typically, this work is done during a maintenance or refuelling outage that occurs once every one to three
years (1-2 months duration), depending on station protocols and an assessment of needs. The periodic chemical cleaning of systems and
components (e.g. steam generators) is also included in this activity. Many maintenance activities do not require a unit shutdown, and will be
performed with the unit in an operating state.
Refurbishment: During the 60 year life of the station, specific reactor components and the steam generators, will likely require replacement. In
addition to the steam generators, refurbishment of the ACR-1000 would require replacement of fuel channel assemblies, calandria tubes and
feeder pipes; and the EPR and AP1000 would require replacement of the reactor pressure vessel head. Each of these activities will require the
reactors being removed from service for a period of time (one to three years).
The reactor will be defuelled, systems will be drained and access ways through containment created. The components will be removed by cutting
or disconnecting piping and equipment.
The Low and Intermediate Level Waste from refurbishment will be transported either to a purpose built facility on-site or transported a licensed
facility is in accordance with CNSC transportation regulations in place at the time of refurbishment.
Replacement /
Maintenance of Major
Components and Systems
Safe Storage: Preparation for, and safe storage of a reactor are the first two of the three-stage decommissioning program (the final stage is
dismantling, disposal and site restoration). Safe storage involves removing the reactors from service for a period of time to allow for decay of
radionuclides. In preparation for safe storage, the reactors will be defueled, and dewatered. During the safe storage period resident maintenance
staff will perform routine inspections and carry out preventative and corrective maintenance.
Physical Presence of the
Station
When complete, NND will exist as a functioning nuclear power plant comprised of up to four individual reactors. The greatest potential difference,
in an environmental context, between the new facility and the existing station are the cooling towers that may be included as an alternative to the
once-through cooling. From a physical presence perspective, natural draft cooling towers would be the more dominant of the cooling tower
options, with several towers likely, each extending to a height of as much as 152.4 m above finished grade. A visible steam plume would routinely
be associated with cooling tower operation.
During operations, used reactor fuel will be stored onsite in water-filled bays for a period of several years, following which it will be removed
from the bays, repackaged into dry storage containers and placed into on-land storage, also onsite, for a period of up to several decades.
Administration,
Purchasing and Payroll
Upon completion of the Construction Phase of the project, the maximum estimated staff required for the operation of NND is expected to be 1,400
for the first two units in approximately 2016, and 2,800 for four units in about 2025. During the period 2018-2024, the workforce involved in the
operation of units 1 and 2 will overlap with the workforce staff associated with the construction of units 3 and 4. During these years the Project-
related workforce will total approximately 5,200.
The Project-related workforce will increase from the normal complement of 2,800 by a further 2,000 during NND refurbishment (approximately
2050-2055).
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APPENDIX B
COMPENSATION DEVELOPMENT OPTIONS TABLE
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B-1
Appendix B: Compensation Development Options Table
Compensation
OptionAdvantages Limitations
Species/
Community
Affected
Benefits to
Local Area
Technical
Feasibility
Compensation
AreaConclusion Rank
Site Study Area
Modification of
infill front and
enhancement of
habitat in the infill
area reduces the
overall footprint.
Will provide near
shore habitat for
Round Goby
community.
Round Goby Would require
additional fill
material, including
a source of round
cobble.
Project occurs in the
SSA but with limited
benefit to diversifying
quality of habitat.
Potential for benefiting
non target and/or
undesirable fish
species. Potential for
increased benefit to
target species in future
years if Round Goby
populations decline.
Consultation with
coastal engineer
required since infill
could affect
currents and
sediment transport.
Modification of
Lake Infill
Design
Enhancement of
near shore habitat
function around the
DN site, if
moderate and
optimally located,
would not result in
a significant
increase in I&E.
Possible increase in
I&E from fish
attracted to the
area.
Warm and cold
water species
Create
additional
complex near
shore habitat
providing a
forage/spawnin
g area for
native species.
Redesign of infill
area would be
required. Design
needs to consider
navigational
constraints.
Would provide a
component of the
compensation plan
but would likely
need to be
combined with
other initiatives.
Overall benefits could
be high since this
option will limit the
infill area and benefit
the SSA.
Modifications would
need to be limited for
habitat compensation
to ensure that I&E
losses would not
substantially increase.
Pass
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effects
Ontario Power Generation Inc. Technical Support Document
B-2
Appendix B: Compensation Development Options Table (Cont’d)
Compensation
OptionAdvantages Limitations
Species/
Community
Affected
Benefits to
Local Area
Technical
Feasibility
Compensation
AreaConclusion Rank
Site Study Area
Compensation can
be in the SSA
and/or LSA. If
compensation is in
the SSA then on-
going management
would be included
under site
biodiversity plan.
Recent 2009
studies indicate
round goby are the
most common
species in the
nearshore and
additional habitat
creation is likely to
favour this species.
Round Goby are
currently the most
prevalent and most
likely to benefit.
Requires
substantially more
fill materials to
provide gentle
slope.
Option to identify
local areas.
Will require source
of round cobble
sufficient for the
area.
Regenerate historic
shoals along Lake
Ontario north shore
area.
Providing
additional onshore
habitat in the SSA
may increase fish
populations in area,
and result in an
increase in I&E.
Under existing
conditions, will
provide habitat for
Round Goby and could
result in an increase in
I&E if compensation is
within the SSA.
However, if Lake
Whitefish stocks
recover, the possibility
exists to increase
habitat for this species
and other salmonids.
Will require
consultation with
coastal engineer to
assess effects on
currents and
sediment transport.
On-shore &
off-shore
shoals*
Compensation in
the LSA could
create additional
habitat without
resulting in
increased I&E.
Success of on-
shore shoals is
unknown.
Salmonid and
forage species may
use habitat in the
longer term if goby
numbers are
reduced in the
future. Goby will
likely feed on
whitefish and other
salmonid species
eggs and larvae.
Enhanced
habitat is
within the local
municipality of
Clarington
Creation of suitable
slopes needs to
consider
navigational needs.
Can provide a
potential
component of
compensation plan,
and large areas can
be considered.
Overall benefits will
be moderate under
existing conditions but
could be of greater
significance in the
future if goby stocks
decline and Lake
Whitefish populations
recover.
Pass
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effects
Ontario Power Generation Inc. Technical Support Document
B-3
Appendix B: Compensation Development Options Table (Cont’d)
Compensation
OptionAdvantages Limitations
Species/
Community
Affected
Benefits to
Local Area
Technical
Feasibility Compensation Area Conclusion Rank
Local Study Area
Compensation is
focused in Local
Study Area (LSA)*.
Watercourse restoration
is small in scale and
would need to consider
a number of projects.
Watercourse
enhancements
would benefit
salmonids and
cyprinids,
including
undesirable
species such as
carp
Enhanced
habitat is
within the local
municipality of
Clarington.
Requires
knowledge of
hydrology and
research into
projects that will
function as
intended but is
technically feasible
in most areas.
Restoration could
provide a substantial
component of the
compensation plan
depending on the
specific initiative
since the quality of
habitat created could
be high.
Quality vs quantity
of habitat needs to
be defined since this
option has the
potential to create
high quality habitat
but not sufficient
quantity to offset
loss.
Coastal wetlands can
be highly productive
areas and the quality
of the habitat created
can be of greater value
than some nearshore
compensation efforts
that create less
valuable habitat.
Coastal wetland
restoration in these
areas has historically
been unsuccessful since
it is dependent on the
condition of the
watercourse.
Requires further
discussion with
CLOCA to identify
local areas that
would be feasible
for enhancements.
This option has high
potential benefits
since compensation
would occur within
the LSA and
Clarington RM and
projects would be
high profile
however quantity
of compensation
would be low.
Restoration –
CLOCA
fisheries
management
plan. Farewell,
Black, Soper,
coastal
wetlands,
barrier
removal/
modification
Effective means to
restore fish
communities to
reaches with
previously restricted
access and improve
water quality and in-
stream habitat
conditions.
Focus of program is
on salmonids but
forage base is likely to
benefit as well.
Carp are prevalent
species and would need
to be controlled.
Removal/modification
of barriers in lower
watershed areas could
allow aquatic invasive
species (e.g. Round
Goby/Sea Lamprey)
access to upstream
reaches.
Coastal wetland
enhancements
would benefit
the local fish
community and
forage base.
Can be "high
profile" project
with anglers,
naturalist and
other
stakeholder
groups
Will require
partnering with
CLOCA to allocate
compensation
funds
Quantity of habitat
replaced will not
offset proposed loss.
Would need to be
combined with other
initiatives.
Need to consider
potential for
invasive species to
access watersheds.
Pass
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effects
Ontario Power Generation Inc. Technical Support Document
B-4
Appendix B: Compensation Development Options Table (Cont’d)
Compensation
OptionAdvantages Limitations
Species/
Community
Affected
Benefits to
Local Area
Technical
Feasibility Compensation Area Conclusion Rank
Local Study Area
Requires
substantially more
fill materials to
provide gentle
slope.
Will require
source of round
cobble sufficient
for the area.
Compensation can be
in the SSA and/or
LSA. If compensation
is in the SSA then on-
going management
would be included
under site biodiversity
plan.
Regenerate historic
shoals along Lake
Ontario north shore
area.
Recent 2009 studies
indicate round goby are
the most common
species in the nearshore
and additional habitat
creation is likely to
favour this species.
Providing additional
onshore habitat in the
SSA may increase fish
populations in area, and
result in an increase in
I&E.
Option to
identify local
areas.
Under existing
conditions, will
provide habitat
for Round Goby
and could result
in an increase in
I&E if
compensation is
within the SSA.
However, if Lake
Whitefish stocks
recover, the
possibility exists
to increase
habitat for this
species and other
salmonids.
Will require
consultation with
coastal engineer to
assess effects on
currents and
sediment transport.
Compensation in the
LSA could create
additional habitat
without resulting in
increased I&E.
Success of on-shore
shoals is unknown.
Round Goby are
currently the
most prevalent
and most likely
to benefit.
Salmonid and
forage species
may use habitat
in the longer
term if goby
numbers are
reduced in the
future. Goby
will likely feed
on whitefish and
other salmonid
species eggs and
larvae.
On-shore &
off-shore
shoals*
Enhanced
habitat is
within the local
municipality of
Clarington
Creation of suitable
slopes needs to
consider
navigational needs.
Can provide a
potential component
of compensation
plan, and large areas
can be considered.
Overall benefits
will be moderate
under existing
conditions but
could be of
greater
significance in
the future if goby
stocks decline
and Lake
Whitefish
populations
recover.
Pass
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effects
Ontario Power Generation Inc. Technical Support Document
B-5
Appendix B: Compensation Development Options Table (Cont’d)
Compensation
OptionAdvantages Limitations
Species/
Community
Affected
Benefits to
Local Area
Technical
Feasibility Compensation Area Conclusion Rank
Regional Study Area
Diversifying
Forage Base
through
Replacement of
Stock
Diversifying forage
base would have local
and lake wide benefits
and would also meet
the objectives of the
Lake Ontario
Management Unit
(LOMU).
Deepwater Cisco
rearing in hatchery only
experimental, project
ongoing in N.Y (Lake
Ontario).
Meets LOMU
objectives
Will require
partnering with
MNR and possibly
N.Y. State
Option would
replace fish I&E
losses from intake
and also compensate
for habitat loss.
High profile
project with lake
wide and local
benefits but
difficult to
observe tangible
improvement.
Deepwater
Cisco species,
Lake Herring,
Round Whitefish
Would fortify efforts
focused on stream
rehabilitation to
enhance salmonid
rehabilitation.
Forage base stocking
does not directly
compensate for habitat
loss.
Fortifies stream
rehabilitation
efforts.
Expertise is
available at
White’s Lake
hatchery
Would need further
discussion with
MNR/DFO
Requires further
discussion with
MNR/DFO.
Would help re-
establish the native
forage base and would
aid in moving away
from dependence on
introduced species
such as Alewife
Hatchery should not
occur within SSA since
may result in increased
I&E (e.g. Port
Washington example in
Lake Michigan)
Could be “high
profile”
especially with
anglers,
naturalists and
other
stakeholder
groups
Potential high costs
for development
and operation.
Could be offset if
can use MNR
hatcheries.
Potential for
high benefits
from this option
since it meets the
LOMU objective
and effects would
extend to
Clarington area.
Potential to
collaborate with MNR
(provincial hatcheries)
or develop a hatchery
within LSA.
Deepwater Cisco
rearing is currently
experimental.
Would provide
potential
compensation under
Section 32 of FA, if
required.
Deepwater
Cisco (
important food
base for Lake
Ontario top
predators )
Pass
New Nuclear - Darlington Aquatic Environment
Environmental Assessment Assessment of Environmental Effects
Ontario Power Generation Inc. Technical Support Document
B-6
Appendix B: Compensation Development Options Table (Cont’d)
Compensation
OptionAdvantages Limitations
Species/
Community
Affected
Benefits to
Local Area
Technical
Feasibility Compensation Area Conclusion Rank
Regional Study Area
Lake Ontario
Areas of
Concern
Hamilton
Harbour (AOC)
Modification of
Hamilton Harbour
(HH) embayment
would equate to large
area of compensation
Warm and cold
water species
HH AOC has been
extensively
monitored and
restoration plans
developed. In need
of corporate
partners to fund
projects.
Potential for large
area
Potential for
large project
partnering that
could have lake
wide benefits but
projects will not
occur in local
area
Possibility to partner
in multi corporation
project for greater
benefits through
habitat creations and
rehabilitation
Indirectly –
forage base
dependent fish
(salmonids)
Would need
confirmation that
lake herring move
into this area of the
lake.
The Fish and
Wildlife Habitat
Restoration Project
in Hamilton Harbour
and Cootes Paradise
proposes to create
372 ha of fish habitat
Overall benefit is
low since site is
far removed from
the SSA and
LSA, and
benefits may not
be significant
relative to other
contributors to
program.
Would need water
quality issues to be
addressed.
Restore historic
whitefish and herring
spawning area
Would benefit entire
Lake Ontario fish
community through
restoration f forage
base.
Hamilton Harbour far
removed from SSA and
LSA.
Modifications
to HH would
aid in
diversifying
entire lake
forage base and
therefore
would benefit
local fish
communities
Pass
Site Study Area (SSA) - The SSA corresponds to the existing DNGS property and approximately 2-3 km into Lake Ontario. The SSA is the area where direct
effects on aquatic habitat and biota are most likely (such as the proposed infill area, offshore intake and diffuser)
Local Study Area (LSA) - The LSA refers to lands and portions of Lake Ontario outside the LSA but within Clarington Area.
* Indicates an option that has been considered at more than one study area scale.
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