City of Toronto Basement Flooding Area 37 Display Boards

1. Welcome
Basement Flooding Remediation and
Water Quality Improvement Master Plan
Environmental Assessment
Study Area 37
Public Information Centre #1
View displays and discuss the study with project staff
Feel free to ask questions and fill out a comment sheet

2. Purpose of Tonight’s Meeting
• To introduce the problem and study approach
• To outline general factors contributing to surface and/or basement
flooding and surface water pollution
• Introduce 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.

3. Purpose of Our Study
• Examine existing stormwater drainage,
combined and sanitary sewer systems to
identify the potential causes of basement
flooding and/or surface flooding (severe
ponding on streets during extreme storms).
• Assess control measures to improve the
water quality of receiving water bodies as
per the City’s Wet Weather Flow Master
Plan.
• Make recommendations to:
– Reduce the risk of future basement
flooding
– Improve the quality of stormwater runoff
before it is discharged to watercourses

4. Study Area
• York-Cedarvale
Area
• Generally bounded
by Bathurst, Dufferin,
St Clair and Eglinton
• Study Area is based
on the tributary
drainage areas for
the combined sewer
system.

5. • The City must meet the requirements of Ontario’s Environmental
Assessment (EA) Act for infrastructure projects.
• This project requires completion of Phases 1 and 2 of the Class EA process
as set out by the Municipal Engineers Association (October 2000, as
amended in 2007, 2011 & 2015), following the Master Planning Process.
We are currently in the late stages 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 Master
Plan Report for
30 Day Review
Notice of
Completion
We are here
PIC #2
Incorporate
Comments
PIC #1

6. 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, combined
sewer and storm drainage systems, flooding history, and operation/maintenance records;
• Conduct field surveys to inventory the number of roof leaders disconnected, survey
catchbasins, identify low lying areas, inspect combined sewer overflow structures, and
inventory storm sewer outfalls;
• Consult with the public via Questionnaire and 1st Public Information Centre, to explain the
problem, introduce the objectives of the EA Study, and invite comments on resident history
of flooding and feedback on potential alternatives to reduce risk of flooding / pollution;
• Develop computer models to:
– Analyze the causes of flooding and to estimate flows under various weather conditions;
– Assess the impacts of stormwater runoff and combined sewer overflows on water quality
in receiving watercourses;
• Develop, assess and refine alternative solutions; and
• Present recommended alternative (at 2nd Public Information Centre) and finalize the study
recommendations with consideration on input from the public and review agencies.
Investigating Basement Flooding:
The Steps Involved
We
Are
Here

7. Stormwater Pollution: The Problem
• Urbanization has altered the pathways
through which stormwater finds its way
back to rivers and lakes.
• Stormwater collects oil, dirt, pet waste and
other pollutants and carries them to rivers
and lakes.
• Relief structures in the combined system,
intended to reduce flood risk, can result in
sewer overflow to the environment.
• This results in degraded water quality as
well as:
• Impacts on fisheries and aquatic
habitat
• Reduced recreational use and
aesthetics.

8. Under normal rainfall events, the storm, combined and sanitary sewer
systems operate as designed. However, during extreme storms, the
following takes place:
• Stormwater flow exceeds the storm sewer capacity and overloads the
system.
• Directly-connected roof drains, especially flat roofs, contribute significant
volumes to the sewer system.
• Water remains on the surface and flows
overland along roads.
• At low lying areas, water accumulates (ponds)
and enters the combined or sanitary sewer system
through manhole covers. This causes sewers to
surcharge and potentially back-up into
basements.
Potential Basement Flooding Factors

9. During these heavy rainfalls, the ground becomes extremely wet and unwanted
water enters the sanitary/combined system through cracks or broken pipes,
cracked maintenance hole walls and loose joints underground. This contributes
to back-up of the sanitary/combined sewers.
Other factors related to sanitary/combined sewer back-up include:
• Shallow groundwater table intersecting the sewers
• Downspouts connected to the sewer (direct or through weeping tiles)
• Water entering the basement from the surface via window sills and reverse-
slope driveways etc. and then through basement floor drains (connected to
the sewer)
• Interconnections between the road storm and combined sewer systems
• Downstream creek and/or trunk sewer water levels
• Grease build-up and/or blockages.
Potential Basement Flooding Factors

10. Typical Sewer System Configuration
Case 1 – Combined Sewer
Note: Typical connections shown,
however, private drainage systems
can be more complex and each one
is unique. For example, there could
be other combinations of
connections shown.

11. Typical Sewer System Configuration
Case 2 – Partially Separated Sewer
Note: Typical connections shown,
however, private drainage systems
can be more complex and each one
is unique. For example, there could
be interconnection between the
combined/sanitary and storm systems
or other combinations of connections
shown.

12. Typical Sewer System Configuration
Case 3 – Separated Sewer – Isolated System
Note: Typical connections shown,
however, private drainage systems
can be more complex and each one
is unique. For example, there could
be interconnection between the
sanitary and storm systems or other
combinations of connections shown.

13. Methods for Reducing Basement Flooding
and Improving Water Quality
Source control measures involve managing stormwater where it
originates (roofs, roads, driveways), before it enters the City’s
sewer pipes.
Source Controls
Conveyance Controls
End-of-Pipe Controls
Conveyance control measures help to control stormwater as it
travels along 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), or control
combined sewer overflow discharge so that it can be treated or
re-released back into the combined sewer system for treatment
at the wastewater plant.

14. Potential Solutions
SOURCE CONTROLS
Rain Barrels Rain Gardens Tree Planting
Residents can help reduce runoff – the water that flows from hard surfaces into the sewer system.
Naturalizing your property lowers the risk of basement flooding and contributes to improving
stormwater runoff quality.
Downspout
Disconnection
Reduce ToxinsPermeable Paving
• Eliminate pesticide/fertilizer use
• Do not let household
chemicals such as paint, oil,
grease, salt, soap, etc. wash to
the storm sewer
• Pick-up pet waste
Soakaway Pits Green Roofs

15. Potential Solutions
SOURCE CONTROLS
Replace Perforated
Maintenance Hole Covers
Additional source control options:
• Sewer Maintenance and Rehabilitation
Involves:
• CCTV, smoke/dye tests, sewer cleaning, relining, and repair
• Street sweeping, seasonal leaf pick-up, catchbasin vacuum cleanouts
Surface Flow Path
Diversion
Pervious
Pavement
These measures can also help reduce the amount of runoff entering the sewer system.
Sealing Maintenance
Hole Covers

16. Potential Solutions
CONVEYANCE CONTROLS
Description
• At existing combined sewer overflow locations, either to a
storm sewer or the natural environment, adjust or remove the
structure to reduce discharge during extreme events
What Does it Involve?
• Redesign of underground structures such as interconnecting
pipes and weirs, to reduce or eliminate overflow
Description
• An engineered pipe system that encourages everyday
rainfall to be infiltrated back into the groundwater table
before running down the storm sewer pipe
What Does it Involve?
• Used where a storm sewer is already being replaced for
flood protection, an additional underground gravel trench
and perforated piping system is connected to encourage
infiltration
Exfiltration/Pervious Pipe Systems
(Improve Stormwater Runoff Quality)
Combined Sewer Overflow
Modifications
(Improve Water Quality)
http://www.hkywater.org/departments/wastewater/combined-sewer-system
http://www.civil.ryerson.ca/urban/techno/stormwater/source/10-2-8/index.html

17. Potential Solutions
CONVEYANCE CONTROLS
Description
• A vegetated depression and underground trench designed
to filter stormwater runoff to remove pollutants and promote
infiltration/evapotranspiration
What Does it Involve?
• Diversion of small overland or piped drainage areas for small
storm events
• Excavation of a trench with specific soil mixture, surface
plantings and underdrain within an open area such as a
boulevard or park
Description
• In place of concrete curb and gutter, replace with grassed
ditches and a series of culverts which slows surface water
down and encourages infiltration/filtration
What Does it Involve?
• Removal of curb and gutter (if existing) and reconstruction
of roadway and boulevard
• Installation of shallow culvert pipes
Alternate Road Cross-Sections (Ditches)
(Improve Stormwater Runoff Quality)
Local Bioretention Filters
(Improve Stormwater Runoff Quality)

18. Potential Solutions
CONVEYANCE CONTROLS
Increase Number of Catchbasins
(Controls Basement Flooding)
Overland (Major System) Control
(Controls Basement Flooding)
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 to dedicated
major system sewer with large inlet grate or “curb
drain”
Description
• Where the storm sewer has existing capacity, add
more catchbasins to capture more flow from the
surface
What Does it Involve?
• Minor street excavation for installation of new
catchbasin(s) and connection to storm sewer
• Curb replacement and road restoration

19. Potential Solutions
CONVEYANCE CONTROLS
Parking Lot Retrofit for Surface Storage
(Controls Basement Flooding)
Catchbasin Inlet Controls
(Controls Basement Flooding)
Description
• Installation of inlet control devices (ICDs) on
catchbasins to limit release into the storm sewer
system to control back-up (surcharge)
What Does it Involve?
• A plastic or metal plate / device installed inside the
catchbasin outlet (not visible from surface)
• Minimal effort and time to install
• Keeps more water on the surface
Description
• Installation of ICDs in parking lots to store stormwater
on 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)

20. Potential Solutions
CONVEYANCE CONTROLS
Adding New Sewers (Twinning)
(Controls Basement Flooding)
Replacement of Existing Storm,
Combined and/or Sanitary
Sewers
(Controls Basement Flooding)
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 limits
• 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
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 limits
• 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

21. Potential Solutions
END-OF-PIPE CONTROLS
Wet Pond/Wetland
(Controls Basement Flooding and Can
Improve Runoff Quality)
Dry Pond
(Controls Basement Flooding)
Description
• An engineered surface depression that controls the quantity of
inflowing stormwater through storage and slow release to the
receiving system
• Typically fills with water during extreme storm events and drains
within 24 to 48 hours or less
What Does it Involve?
• Excavation and shaping of a suitable open space
• Addition of inlet/outlet structures
• Restoration and landscaping; signage
Description
• An engineered pond or wetland with a permanent water surface
that controls the quantity and quality of inflowing stormwater
through storage and slow release to the receiving system
What Does it Involve?
• Excavation and shaping of a suitable open space
• Addition of inlet/outlet structures
• Restoration and landscaping (aquatic and side-slope)
• Infrequent maintenance (sediment removal)

22. Potential Solutions
END-OF-PIPE CONTROLS
Oil & Grit Separator
(Improves Stormwater Runoff Quality)
Underground Storage Tank
(Controls Basement Flooding & Can Improve
Water Quality)
Description
• An underground tank or pipe that controls the rate of
inflowing sanitary or stormwater through temporary
detention and slow release to the receiving sewer,
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)
Description
• An underground separation tank that takes the place of a
conventional manhole and provides a measure of
treatment for small drainage areas
What Does it Involve?
• Similar to a manhole, minor street excavation for
installation of structure
• Road restoration
• Annual maintenance (vacuum clean-out)

23. The following criteria are suggested for evaluating each of the options and
identifying the recommended solutions:
Evaluation of Solutions
Natural Environment
• Potential Impact on
Terrestrial Systems
(Vegetation, Trees,
Wildlife)
• Potential Impact on
Aquatic Systems
(Aquatic Life and
Vegetation, Surface
Water Quality,
Groundwater,
Receiving
Watercourses)
• Soil and Geology
Socio-Cultural
• Effect on Urban
Greenspace (Parks,
Ravines, 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
• Feasibility of Control
Measure (Available
Space, Accessibility,
Constructability)
• Ability to Improve Water
Quality
• Impact on Upstream,
Downstream and
Surrounding Areas
• Operations &
Maintenance
Requirements
• Basement Flooding
Prevention Effectiveness
Economic
• Capital Cost
• Operating and
Maintenance Cost

24. 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 PIC is expected to be held in late 2016 to present the recommended solutions.
Contact Information
For more information on this study, to provide your comments, or to be placed on the
project mailing list, please contact:
Mae Lee, Public Consultation Unit
55 John Street, Metro Hall, 19th Floor, Toronto, ON M5V 3C6
Phone: 416-392-8210, E-mail: rmlee@toronto.ca
Website: http://www.toronto.ca/bfea