Black Creek Sanitary Drainage Area Servicing Improvements Class Environmental Assessment Study

The purpose of this Environmental Assessment Study is to recommend improvements for the Black Creek Sanitary Trunk Sewer (STS) system

This Environmental Assessment Study is not focused on basement flooding• The Basement Flooding Protection Program is separately

addressing basement flooding issues at the local sewer level• Information from the Basement Flooding Protection Program

studies will inform the analysis and recommendations made for the Black Creek STS Environmental Assessment

WelcomeBlack Creek Sanitary Drainage Area Servicing ImprovementsMunicipal Class Environmental Assessment StudyPublic Information Centre

Date: April 26 and April 28, 2016Time: 6:00 pm to 8:00 pm

Please sign in to receive project updates on the study. Please provide your comments by completing a comment sheet and placing it in the box or forwarding it to the Project Team by May 20, 2016.

Purpose of Today’s Information Session

• Present the purpose and objectives of the study• Provide background on the Black Creek Sanitary Trunk Sewer System• Present the problems and opportunities for the study• Present potential solutions to be considered• Present draft criteria for evaluating alternatives• Receive your comments

We Want to Hear From YouYou can participate by:• Signing in at the attendance register• Reviewing the display panels• Asking questions from City Staff and Consultants• Completing a comment form• Participating in future Public Information Centres

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Study Purpose and Objectives

The purpose of this study is to assess capacity issues with the Black Creek Sanitary Trunk Sewer (STS) system, identify solutions and develop a plan to achieve the following objectives:• Service projected population growth in the sanitary drainage area to 2041• Reduce surcharge levels in the Black Creek STS during wet weather events• Reduce combined sewer overflow discharges to Black Creek• Reduce Inflow and Infiltration into the Black Creek STS

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Municipal Class Environmental Assessment Process – Schedule C

• Identify the Problem/ Opportunity

• Consult with Public, Agencies, Stakeholders

• PIC #1 April 2016

Phase 1

• Review of background studies, relevant EAs and existing conditions

• Develop and Evaluate Alternative Solutions

• Consult with Public, Agencies, Stakeholders

• PIC #2 • Select a Preferred

Solution

Phase 2

• Identify Design Concepts

• Consult with Public, Agencies, Stakeholders

• PIC #3 • Select the

Preferred Design Concept

Phase 3

• Complete Environmental Study Report

• File Environmental Study Report for Review by Public, Agencies, Stakeholders

Phase 4

Weare

here

30 DayReview Phase 5

• Design, Construct and Monitor

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Black Creek Sanitary Trunk Sewer System and Drainage Area• The Black Creek STS was built in the 1960’s• It is a tributary to the Humber Sanitary Trunk Sewer and discharges into

the Humber Wastewater Treatment Plant• The Black Creek STS is 15 km long, from Finch Avenue West to Scarlett

Road• The Black Creek STS services a sanitary drainage area of 5,700 ha• It services a population of 386,100 in 2011 (70% residential, 30%

employment)• 80% of the sanitary drainage area has separated local sanitary and

storm sewers; 20% has local combined sewers• There are 3 combined trunk sewers that connect to the Black Creek

STS:• Hillary Combined Trunk Sewer• Mt. Dennis Combined Trunk Sewer• St. Clair Combined Trunk Sewer

• There are 8 combined sewer overflow structures that control flows to 7 combined sewer outfalls

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Overflow structures divert, or bypass flows to relieve an overloaded sewer

Outfalls from the combined trunk sewers to Black Creek

Study Area (portrait orientation)

Study Area (portrait orientation)

Separated Sanitary Sewer System

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Combined Sanitary Sewer System

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Servicing Population Growth

Problem:• Residential and Industrial/Commercial/Institutional populations are expected to grow within the study area• Population growth may increase capacity constraints on the Black Creek STS

Objective:• Ensure capacity in the Black Creek STS to service population growth to 2041 and beyond

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Sanitary Trunk Sewer Surcharge Levels During Wet Weather Events

Problem:• Surcharge of the Black Creek STS happens when the flows through the trunk sewer exceed its design capacity• This may occur due to inflow during large storm events when large

amounts of stormwater enter the Black Creek STS. • Excessive flows in the Black Creek STS may backup into local sewer

systems, valleys and ground surface.

Objective:• Reduce Black Creek STS surcharge levels to the ground surface and valleys and potential impacts on the local sewer systems

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Water Inflow/Infiltration to the Black Creek STS

Problem:• Significant amounts of wet weather flows enter the Black Creek STS during rain events. The sources of the inflow/infiltration may be:• Connections in the local sanitary and combined sewers • Leakages in the trunk sewers, for example, openings in the

maintenance hole covers which allow water into the sewer• Water level increases in the creek/rivers, water gets inside the trunk

sewer via combined sewer outfalls and manholes that are located in the floodplains

Objective:• Reduce Inflow/Infiltration water entering the Black Creek STS to reduce capacity constraints.

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Sanitary Trunk Sewer Surcharge Levels and Inflow/Infiltration (I&I) During Wet Weather Events

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Combined Sewer Overflows

Problem:• Combined trunk sewers carry a mixture of stormwater and

domestic sewage. During rainstorms, or high levels of snowmelt, excess flow can result in discharge of combined sewer overflow from outfalls to Black Creek

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Objectives:• Reduce discharges of combined sewer

overflows to meet the Ministry of Environment and Climate Change Procedure F-5-5• Procedure F-5-5 requires efforts be made to

eliminate combined sewer overflows• Improve water quality in Black Creek

and downstream watercourses

Potential Solutions Being Considered for the Development of Alternatives• New relief trunk sewer: Construction of new trunk sewers to

accommodate future growth and provide a relief to Black Creek Trunk Sewer • Combined sewer overflow storage tank: Temporary storage tanks

allow storage of additional flow during storm events until there is capacity in the downstream infrastructure

• Flow diversion: Diverting flow to other sewers in specific locations to address capacity constraints in those locations.• Flow control structures: Making adjustments to existing flow control

and combined sewer overflow control structures• Maintenance hole adjustments: Raise maintenance holes and

reduce number of openings in maintenance hole cover15

Storage tanks are underground andsurface areas are landscaped to pre-construction conditions

How We Are Developing Alternative Solutions

Technical, environmental and cultural studies are being completed. The work to develop alternative solutions involve:• Review of background information and

previous studies• Data collection• Rainfall and flow monitoring• Water quality sampling• Modelling trunk sewer capacity and

combined sewer overflows under current and future conditions• Geotechnical and other field investigations• Environmental impact assessments• Stage 1 Archaeological and Cultural Heritage

Assessments 16

Draft Evaluation Criteria for Alternative Solutions

Alternative solutions and selection of a preferred alternative will be evaluated based on their ability to address the Study’s Problem and Opportunities, stakeholder input, and potential impacts based on the criteria belowNatural Environment

• Terrestrial impacts (e.g. trees, vegetation, wildlife)

• Aquatic habitat impacts (e.g. water quality, erosion and sedimentation impacts)

• Soil • Geology

Social • Public Health and Safety• Disruption to the community

(e.g. noise, dust, traffic)• Impact to public property and

recreational use• Cultural heritage and

archaeological impacts• Odour issues

Technical • Constructability• Regulatory approvals• Capacity for future growth• Reduce combined sewer overflows• Reduce surcharging• Impacts to local infrastructure and the

Humber Wastewater Treatment Plant

Cost • Capital cost• Risk/benefit analysis• Operations and maintenance costs

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Next Steps for the Black Creek Sanitary Drainage Area Servicing Improvements Environmental Assessment

Phase Phase 1 Phase 2 Phase 3 Phase 4

TaskIdentification of Problem and

Opportunity

Identification of Alternative Solutions

Identification of Alternative

Design Concept

Environmental Study ReportIdentify

Alternatives

Assess and Recommend

Preferred Alternative

Month N D J F M A M J J A S O N D J F M A M J JYear 2015 2016 2017

PIC#1 PIC#2 PIC#3

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After today’s meeting:• Finalize hydraulic model• Develop alternative solutions• Evaluate alternative solutions and recommend a preferred solution• Present alternatives evaluation and preferred solution at Public Information Centre #2

in late 2016 for feedback

30 Day Review

Thank You for Attending

We welcome your feedback. Please fill out the comment sheet provided.Following this PIC, the project team will review and consider your comments in the evaluation of alternative solutions.

Mae LeePublic Consultation UnitCity of Toronto55 John Street, Metro Hall 19th Floor, Toronto, ON M5V 3C6Phone: 416-392-8210 Fax: 416-392-2974 TTY: 416-338-0889 Email: rmlee@toronto.caVisit: toronto.ca/blackcreekstudy 19