Welcome Investigation of Basement Flooding and Stormwater

Runoff Quality Control Study Area 36 (Etobicoke)

Class Environmental Assessment

Public Information Centre #1

View displays and discuss the study with project staff

Feel free to ask questions and fill out a comment sheet

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Purpose of Tonight’s Meeting • To provide background on the study

purpose and objectives. • To present information on the potential

causes and factors contributing to flooding in the area and the impacts of stormwater runoff.

• To present possible alternative solutions and criteria for evaluating the alternatives.

• Outline the next steps in the study process.

• Hear from you! Your input is very important

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Purpose of Our Study • Examine and analyze existing sanitary

sewer and storm drainage systems and identify the causes of basement and surface flooding (severe ponding on streets during large storms).

• Assess control measures to improve the quality of stormwater surface runoff as per the City’s Wet Weather Flow Master Plan.

• Assess alternative solutions to reduce the risk of basement and/or surface flooding.

• Make recommendations to: – Reduce the risk of future basement and/or

surface flooding; and – Improve the quality of stormwater runoff

before it is discharged through storm outfalls to area watercourses.

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Study Area 36 • The Study Area is

generally bounded by: Bethridge Road to

the north; Gracie Boulevard/

LaRose Avenue to the south;

Scarlett Road/ Humber River to the east; and

Iron Street/ Precision Road to the west.

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This area has historically experienced basement and surface flooding during major storm events.

Study Area 36

• There are thirty (30) storm sewer outfalls that discharge stormwater to Humber Creek.

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OF3928002026 OF3865003448

• The City must meet the requirements of Ontario’s Environmental Assessment (EA) Act for infrastructure projects.

• This study is being planned as a Master Plan. This requires the completion of Phases 1 and 2 of the Class EA process. We are currently at the end of Phase 1.

• The EA process is an opportunity for the public and agencies to provide input. Consultation is facilitated via two rounds of Public Information Centres (PICs).

Municipal Class Environmental Assessment Process

PHASE 1 PHASE 2

Problem Or Opportunity

Alternative Solutions

Submit Project File for 30 Day

Review Project

Completion

We are here

PIC #2

Incorporate Comments

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PIC #1

Many steps are involved in the study before solutions can be recommended. This work includes: • Collect and review background data on land use, population, soil conditions, sanitary sewers and

storm drainage systems, flooding history, and operation/maintenance records;

• Conduct field surveys to inventory the number of roof downspouts disconnected, survey catchbasins, identify low lying areas, and inventory storm sewer outfalls;

• Identify preliminary potential causes of basement and surface flooding based on the background data review and results of field surveys;

• Develop and receive feedback on alternatives methods to reduce the risk of flooding and improve stormwater runoff water quality (1st Public Information Centre); • Develop computer models to analyze the causes of flooding and to predict flows under various

weather conditions and assess stormwater runoff impacts to receiving watercourses; • Develop and analyze alternatives to reduce the risk of flooding; • Gather input from the community and review agencies and undertake further assessment and

refinement of the alternatives; and,

• Present recommended solutions (at 2nd Public Information Centre) and finalize the study recommendations based on input from the public and review agencies.

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Investigating Basement Flooding: The Steps Involved

We Are Here

Under normal rainfall events, the storm and sanitary sewer systems operate as designed. However, during extreme storms, the following can take place: • Stormwater flow exceeds the storm sewer capacity and overloads the system; • Directly connected roof downspouts contribute significant volumes to the sewer

system;

Basement Flooding

• Water remains on the surface and flows overland along roads during larger storm events. Excess surface water may enter basements through basement doors and windows;

• At low lying areas, water accumulates (ponds) on the surface and enters the sanitary sewer system through manhole covers. This causes the sanitary sewers to surcharge and potentially back-up into basements.

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During these heavy rainfalls, the ground becomes extremely wet and water enters the sanitary system through cracks or broken pipes, cracked maintenance hole walls and loose joints underground. This contributes to back-up of the sanitary sewers. Other factors causing sanitary sewer back-up include: • Shallow groundwater table is above the sanitary sewer system in parts of Area 36; • Water can enter basements from the surface via basement doors and windows

and then enter the sanitary sewer system through floor drains; • Downspouts and weeping tiles connected to the sanitary system; • Illegal cross-connections between the storm and sanitary sewer systems; and • Oil/grease dumped into sanitary sewers causing blockages.

Basement Flooding

Typical Causes of Basement Flooding

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• Urbanization has increased surface runoff, decreased infiltration into the ground and increased the potential for the transport of pollutants via surface runoff from streets, parking lots and other hard surfaces.

• Stormwater runoff often contains grit, oil/grease, heavy metals (zinc, lead, etc), bacteria, nitrates/sulfates, salt and other pollutants.

• Pollutants in the stormwater runoff adversely impact the water quality of the receiving watercourse, which can affect fisheries, wildlife, recreational uses, and visual aesthetics, etc.

Stormwater Runoff Quality

Methods for Reducing the Risk of Basement and Surface Flooding and

Improving Water Quality Source control measures involve managing stormwater where it originates (roofs, roads, driveways), before it enters the City’s sewer systems.

Downspout disconnection Rain barrels Catchbasin inlet controls Surface flow path

diversion Bioretention units Sanitary sewer

rehabilitation

Source Controls Conveyance Controls

These measures include: Alternate road cross-sections (grassed

ditches / swales) Bioretention units and bioswales Overland flow control Sewer pipe diversion, replacement or

twinning

End-of-Pipe Controls

These measures include: Surface dry ponds Surface wet ponds Underground storage tanks or

underground storage pipes

Conveyance control measures help to control stormwater as it travels and enters the drainage system (in pipes or along the road).

End-of-pipe control measures control stormwater just before it is discharged to a watercourse (stream, river, or lake).

These measures include:

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Potential Solutions – Source Control

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Sealing and Plugging Maintenance Hole Covers

Surface Flow Path Diversion

Additional source control options: • Increasing the number of catchbasins; • Pervious driveways; and • Rehabilitating sewer systems to reduce

inflow/ infiltration (I/I) based on CCTV inspections.

‘Pick Holes” plugged with rubber insert

Most source control measures help to reduce the risk of basement flooding and also contribute to improving stormwater runoff quality.

Downspout Disconnection

Rain Barrel

Potential Solutions in the Study Area

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Inlet Control Devices

SOURCE CONTROLS

Description • Inlet Control Devices control the amount of water that

enters the storm sewer system during a storm event.

• Allows excess stormwater to remain in catchbasins or temporarily on the street until the storm subsides.

• Helps prevent overloading of the storm sewer system and sewer backups.

What Does it Involve? • An Inlet Control Device is installed inside the catchbasin.

It is not visible from the surface.

• Minimal time and effort are needed to install an Inlet Control Device.

Potential Solutions in the Study Area

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Bioswales Description • A vegetated depression and underground trench designed to

convey and filter stormwater. A Bioswale slows down the flow of stormwater and can help protect downstream areas from surface flooding and improve stormwater runoff quality.

What Does it Involve? • Diversion of small overland or piped drainage areas for small

storm events. • Excavation of a trench with specific soil mixture and surface

plantings and underdrain within an open area such as a boulevard or park.

CONVEYANCE CONTROLS

Local Bioretention Units

Potential Solutions in the Study Area

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Overland Flow (Major System) Control Description • The diversion of surface drainage away from low lying

areas that have no direct outlet, to reduce surface ponding depths.

What Does it Involve? • Addition of “speed bump” or “curb cut” to redirect

overland flow to strategic locations. • Interception of road or boulevard flows with large inlet

grate or “curb drain” to dedicated major system sewer.

Public Parking Lot Retrofit for Surface Storage Storage

Description • Installation of Inlet Control Devices in parking lot

catchbasins to store stormwater on the surface. • Installation of roof drain controls to store stormwater on

large flat roof areas.

What Does it Involve? • Retrofit of City-Owned property (where physically

possible).

CONVEYANCE CONTROLS

Potential Solutions in the Study Area

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Replacement of Existing Storm and/or Sanitary Sewers

Description • Increase the size of the sewer pipe by replacing the old

sewer with a larger pipe.

What Does it Involve? • Road excavation within City’s Road Right of Way. • Removal of old sewer and structures (manholes &

catchbasins) and disconnection of sewer service line(s). • Placement of new sewer, reconnection of sewer service

line(s) and restoration of road and boulevard.

Adding New Sewers (Twinning) Description • Increase the capacity of the sewer system by adding

another sewer pipe in addition to the existing pipe.

What Does it Involve? • Road excavation within City’s Road Right of Way. • Replacement of old structures (manholes & catchbasins)

and reconnection of sewer service line(s) if necessary. • Placement of new sewer, reconnection of sewer service

line(s) and restoration of road and boulevard.

CONVEYANCE CONTROLS

Potential Solutions in the Study Area

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Wet Stormwater Management Pond/Wetland Description • Wet stormwater management ponds and wetlands have

a permanent water surface that controls the quantity and quality of inflowing stormwater through storage and gradual release to the receiving system.

What Does it Involve? • Excavation and shaping of a suitable open space area. • Addition of inlet/outlet structures. • Restoration and landscaping (aquatic and side-slope). • Infrequent maintenance (sediment removal).

Dry Stormwater Management Pond

Description • An engineered surface depression that controls the

quantity of inflowing stormwater through storage and gradual release to the receiving system.

• Typically fills with water during large storm events and drains within 24 to 48 hours or less.

What Does it Involve? • Excavation and shaping of a suitable open space area. • Addition of inlet/outlet structures. • Restoration and landscaping.

END-OF-PIPE CONTROLS

Potential Solutions in the Study Area

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Underground Storage Tank

Description • An underground tank that controls the rate of inflowing

sanitary or stormwater through temporary storage and gradual release to the receiving sewer, thereby reducing the potential for flooding.

What Does it Involve? • Excavation and construction of tank or pipe, including

inlet and outlet structures. • Infrequent maintenance (monitoring, clean-out). • Restoration and landscaping.

Storage Pipes Description • An underground pipe that controls the rate of inflowing

sanitary or stormwater through temporary storage and slow release to the receiving sewer, thereby reducing the potential for flooding.

What Does it Involve? • Excavation and additional of inlet/outlet structures. • Road restoration.

END-OF-PIPE CONTROLS

Maintenance Hole

Street Level

Maintenance Hole

Maintenance Hole Maintenance Hole

Evaluation of Solutions

Natural Environment • Potential Impact on Terrestrial Systems

(Vegetation, Trees, Wildlife). • Potential Impact on Aquatic Systems

(Aquatic Life and Vegetation, Surface Water, Groundwater).

• Soil and Geology.

Socio-Cultural • Land Use Impacts (Parks, Ravines,

and Open Spaces) • Disruption to Existing Community

During Construction (Traffic, Noise) • Disruption to Existing Community

Post Construction (Visual Impact, Odour, Safety)

• Archaeology and First Nations

Technical • Effectiveness of control measure in reducing

surface and basement flooding and improving stormwater runoff quality.

• Feasibility of Control Measure (Available Space, Accessibility, Constructability)

• Impacts on upstream, downstream and surrounding area infrastructure.

• Impacts on operating and maintenance requirements.

Economic • Capital cost • Operating and Maintenance Costs

Economic

The following criteria are suggested for evaluating each of the alternatives and identifying the recommended solutions:

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What are your thoughts on the evaluation criteria? Are there any additional criteria that should be considered?

Thank You for Attending

We welcome your feedback. Please fill out the comment sheet provided. Following this PIC, the study team will review and consider your comments in

the evaluation of alternative solutions. The next Public Information Centre will be held in late 2016 to present the

recommended solutions.

Contact Information For more information on this study, or to provide your comments or be placed on the

project mailing list, please contact:

Josie Franch, Public Consultation Unit 55 John Street, Metro Hall, 19th Floor, Toronto, ON M5V 3C6

Phone: 416-338-2859, E-mail : jfranch@toronto.ca Fax: 416-392-2974, TTY: 416-338-0889

Website: http://www.toronto.ca/bfea 21

What Can Homeowners Do to Prevent Future Flooding?

1. Residents are encouraged to complete an investigation of their property to identify potential causes of flooding.

2. Actions that may help reduce the risk of basement flooding should be investigated. These include: • Ensure yard is graded away from house, and downspouts discharge

away from foundation • Waterproofing basements • Replacing weeping tiles • Capping and severing the weeping tile connection to the City’s system • Installing a sump pump with backup power • Backflow valve on the sanitary sewer

Basement Flooding Protection Subsidy Program

To assist homeowners, the City offers owners of single-family, duplex and triplex residential homes, a financial subsidy of up to $3,400 per property, to install flood protection devices including:

• Backwater valve (max $1,250), • Sump pump (max $1,750), and • Disconnection of a home’s foundation

drains (weeping tile) from the sewer system (max $400).

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BELFIELD RD

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Basement Flooding Area 36

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Humber RiverHumber Creek

Black CreekMimico Creek

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BasementFloodingAreasKey Map

Legend_̂ Reported Basement Flooding

Basement Flooding AreaExtended Contributing StormDrainage Area

"P Storm Pumping StationManholes

!( Sanitary!( Storm!+ Outfalls

SewersSanitaryStorm