ICMC Meeting #3 March 2015 MEETING AGENDA Introduction of ICMC - - PowerPoint PPT Presentation

Ashbridges Bay Treatment Plant Outfall Conceptual Design & Receiving Water Assessment

ICMC Meeting #3

March 2015

MEETING AGENDA

• Introduction of ICMC & Project Team
• Meeting Objective
• Project Background
• Evaluation of Alternatives
• Project Implementation
• Achieved Outcomes
• Discussion

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INTRODUCTIONS

• Personal Introductions
• Project Team
• CH2M HILL – Prime consultant for outfall modelling
• Hatch Mott MacDonald – Outfall conceptual design
• Baird – Lake modelling and sediment modelling
• Previous ICMC Meetings
• March 2012 – Background and Project Approach
• October 2013 – Preliminary Evaluation of Alternatives

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Meeting Objective

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To obtain ICMC input on the draft conceptual

• utfall design.

MEETING OBJECTIVE

PROJECT BACKGROUND

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WHY ARE WE LOOKING TO REPLACE THE EXISTING OUTFALL?

• The existing outfall was

constructed in the late 1940s and has insufficient capacity

• The existing outfall does not

meet current regulatory standards

• For these reasons a

commitment to the public was made to replace it

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PROJECT OBJECTIVE & SUCCESS FACTORS

• Project Objective
• Deliver a conceptual design for a new outfall that meets

regulatory acceptance and improves nearshore water quality in Lake Ontario

• What are the important success factors for the

project?

• Achieve regulatory endorsement and acceptance on the

Conceptual Design

• Gain stakeholder understanding
• Develop an economically and environmentally feasible solution

PROJECT OBJECTIVE & SUCCESS FACTORS

• Your key success factors
• Reduce impacts on the natural environment
• Effective stakeholder process
• Fulfills EA commitments
• Timely project completion

(From March 2012 ICMC meeting)

EVALUATION OF ALTERNATIVES

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EVALUATION PROCESS

We were here at the last ICMC meeting in October 2013 We are now here

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SCREEN OUTFALL CONFIGURATIONS Recap from previous meeting

Outfall Lengths that Passed Screening 2700m 3500m

• Configurations based on 1986 preferred

alignment which is clear of buried valley and ridge features

• “Must Have” Screening Criteria included:
• Mixing performance
• Water quality at water treatment plant intakes
• Water quality at recreational beaches
• Longer outfall lengths met mixing and water

quality criteria

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• Tunnel

Construction

• Open Cut

Construction

• Hybrid Construction

DEVELOP OUTFALL ALTERNATIVES Construction Approaches

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Criteria Categories:

• Technical – Ease of implementation, operation and maintenance
• Natural – Aquatic systems, terrestrial systems, air quality
• Social – Public health, safety of plant and construction workers,

quality of life

• Economic – Life-cycle costs

ASSESS OUTFALL ALTERNATIVES Evaluation Criteria

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ASSESS OUTFALL ALTERNATIVES Tunnel Construction

• No dredging required - minimizes social and natural impacts
• Fewer permits
• Less complex to construct

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ASSESS OUTFALL ALTERNATIVES Open Cut Construction

• Shoreline excavation and shallow water dredging – high

social and natural impacts

• More permit requirements
• Construction limited by weather and timing windows

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ASSESS OUTFALL ALTERNATIVES Hybrid Construction

• Dredging in deeper water – fewer social and natural impacts
• Moderate permit requirements
• A portion of construction is limited by weather and timing

windows

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• Single tunnel
• Similar to 1986 Concept
• 7.0m internal diameter
• 3500m length
• Tunnel Boring Machine

(TBM) in bedrock

• 61 vertical “tunnel risers”
• 61 diffuser ports

RECOMMENDED ALTERNATIVE 3500m Tunnel

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RECOMMENDED ALTERNATIVE 3500m Tunnel

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Total Project Cost (2020 CAD) $340M Total Estimated Project Duration 7.3 years

RECOMMENDED ALTERNATIVE Cost Estimate and Schedule

2015 2016 2017 2018 2019 2020 2021 2022

Completion Tender Award Project

Construction Design

ACHIEVED OUTCOMES

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• Capacity shortfall of existing outfall has been addressed
• New outfall peak capacity will be 3,900 million litres per day
• Outfall is designed to not discharge through seawall gates to

Ashbridges Bay

INCREASED OUTFALL CAPACITY

IMPROVED NEARSHORE WATER QUALITY

PROPOSED OUTFALL

EA CONDITIONS HAVE BEEN MET

EA Condition Is the Condition Met?

Condition (1) – Document effluent quality for blended effluent during secondary bypass events.

YES

Condition 10 (ii) – Meet Provincial Water Quality Objectives (PWQO) at the edge of the mixing zone

YES

Condition 10 (iii) – Mitigate impacts on the Island and Harris WTPs

YES

Condition 10 (iii) – Eliminate need for seawall gates

YES

Condition 10 (viii) – Mitigate impacts on the beaches and shoreline

YES

Condition 12 – Mitigate impacts on fish and fish habitat

YES

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• Met with the ICMC at each stage of this project
• We will finalize the conceptual design after receiving your input

COMMITMENT TO THE PUBLIC

DISCUSSION

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