PIC 2 display boards

1. Welcome
Investigation of Basement Flooding and
Stormwater Runoff Quality Control
Study Areas 21 & 23
Public Information Centre #2
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 provide background and review the study process / findings for Study
Areas 21 & 23
• To present preliminary recommended solutions to alleviate surface and
basement flooding and improve stormwater runoff quality to the
receiving watercourses including Wilket Creek and the East Don River
• Hear from you! Your input and comments are very important and will be
considered in finalizing the preferred solutions for the study
• Outline the next steps in the study process

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

4. Study Areas
• The Study Areas 21 & 23
are based on the
tributary drainage areas
for the sanitary and
storm sewer systems.
• These areas have
experienced surface
and basement flooding
during extreme storm
events (May 12, 2000,
August 19, 2005, July 8,
2013 and others).
• Storm sewers in both
areas primarily drain to
the East Branch of the
Don River. A small area
drains to Wilket Creek.

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. We are currently in the
final stages of Phase 2.
• 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 #1 &
PIC #2
Incorporate
Comments

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, sanitary 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, and inventory storm sewer outfalls
• Develop computer models to:
– Analyze the causes of flooding and to predict flows under various weather conditions
– Assess the impacts of stormwater runoff on water quality in receiving watercourses
• Develop and receive feedback on potential alternatives to address the issue of flooding in each
basement flooding area and improve stormwater runoff water quality before it is discharged to
the receiving watercourses (1st Public Information Centre held on June 24, 2014)
• Identify and assess alternatives and present recommended solutions (2nd Public Information
Centre)
• Gather input from the community and review agencies and undertake further
assessment and refinement of alternatives
• Finalize EA study based on input from public and review agencies.
Investigating Basement Flooding:
The Steps Involved
We Are
Here

7. Areas of Responsibility
Typical Sump Pump
Typical Foundation Drain
Typical Rear-yard Catchbasin
Watermain
Storm
Lateral
The homeowner is responsible for the
operation of drainage systems on
private property, including grading,
front and rear-yard or driveway
catchbasins, foundation drains, sump
pumps, backwater valves, service
laterals, tree roots, downspouts, and
what you put down the drains (fats, oils,
grease, non-disposable wipes, etc.).
Water
Service
Roof
Downspout
Catch
Basin
Fire
Hydrant
Rear-yard
Catchbasin
Sanitary
Lateral
Storm
Lateral

8. Drainage Systems Design and Operation
• Storm sewers (minor system) drain runoff generated from everyday rainfall events,
defined as the 1 in 2 year design storm (50% chance that an event of this magnitude
will occur in any year).
• Streets and overland flow paths (major system) convey major rain storms that exceed
the storm sewer capacity.
• Temporary ponding on streets is expected during these major rain storms.
Street Right-of-Way
Water Level in Street to be Within Right-of-Way Limits
Sanitary
Sewer to
Treatment
Plant
Storm
Sewer to
Don River
Catch
Basin
Water Level in Storm Sewer to be Below
Basement Elevation up to 1 in 100 year storm (1%
chance of occurring in any year)
Water Level in Sanitary
Sewer to be Below
Basement Elevation

9. Under normal rainfall events, the storm 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 sanitary sewer system through
manhole covers. This causes the sanitary
sewers to surcharge and potentially back-up
into basements.
Our Basement Flooding Findings

10. During 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.
Factors related to sanitary sewer back-up include:
• Shallow groundwater table intersecting the sanitary sewer
• Downspouts connected to the sanitary system 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
sanitary sewer)
Our Basement Flooding Findings

11. Typical Causes of Basement Flooding
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.

12. • Urbanization has not only increased the volume of surface runoff and
decreased infiltration into the ground, but has also increased the potential for
transport of pollutants from streets, parking lots and other hard surfaces to
receiving watercourses.
• Stormwater runoff often contains grit, oil/grease, heavy metals (zinc, lead,
etc.), bacteria, nitrates/sulfates, salt and other pollutants.
Our Stormwater Runoff Quality Findings
• These pollutants adversely impact the water
quality of the watershed, affecting fisheries,
wildlife, recreational uses, visual aesthetics, etc.
• There are 31 storm sewer outfalls in Area 21 and
19 in Area 23
• Most of these outfalls are ultimately tributary to
the East Branch of the Don River except for five
outfalls in Area 21 which flow to Wilket Creek.Area 21 Outfall

13. The following criteria were used to evaluate strategies and identify the
recommended solution alignments:
Evaluation of Solutions
Natural Environment
• Potential Impact on
Terrestrial Systems
(Vegetation, Trees,
Wildlife, Stream Erosion)
• 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
Stormwater Runoff
Quality
• Impact on Upstream,
Downstream and
Surrounding Areas
• Operations &
Maintenance
Requirements
• Basement Flooding
Prevention Effectiveness
Economic
• Capital Cost
• Operating and
Maintenance Cost

14. Methods for Reducing Basement Flooding
and Improving Stormwater Runoff 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).

15. Recommended 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

16. Downspout Disconnection
SOURCE CONTROLS
The City has a By-Law making downspout
disconnection mandatory in basement
flooding areas, where feasible.
Benefits of Disconnecting your Downspout:
• Helps reduce the amount of stormwater
that is sent into the sewer system.
• Helps to replenish and protect the
groundwater table and reduces and
delays stormwater runoff – helping to
prevent flash flooding in rivers and
streams.
• Less stormwater in the system will help
prevent wastewater from backing up
into basements.
• Leads to lower energy costs at
wastewater treatment facilities –
producing fewer greenhouse gas
emissions.
• This bylaw came into effect December 3, 2013 for
properties in basement flooding areas.
• For combined sewer service areas and properties
outside basement flooding areas, this bylaw will
come into effect December 3, 2016.
• If disconnection is not technically feasible or would
create a hazardous condition, owners can apply
to the City for an exemption.

17. Recommended Solutions
SOURCE CONTROLS
Sealing Maintenance
Hole Covers in Low
Lying Areas
Additional Source Control Recommendations:
• Sanitary Inflow and Infiltration Monitoring and Investigations to plan strategic maintenance and
rehabilitation programs
• Sewer Maintenance and Rehabilitation
Surface Flow Path
Diversion
Pervious
Pavement
These measures can also help reduce the amount of runoff entering the sewer system.
o Sanitary Sewer: CCTV inspections, smoke/dye tests, sewer cleaning, relining, and repair
o Storm System: Street sweeping, seasonal leaf pick-up, catchbasin vacuum cleanouts, sewer
flushing, CCTV inspections

18. Recommended 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
Recommended Locations
• Investigate opportunities associated with any road
reconstruction effort, in tandem with community input
Description
• Alternate method of storm sewer construction which slows runoff
during everyday rainfall and encourages filtering of pollutants
through a gravel medium before entering the storm sewer
What Does it Involve?
• During road reconstruction work, excavation of a trench and
reconnection of catchbasins to a new perforated pipe system
Recommended Locations
• Investigate opportunities associated with any sewer / road
reconstruction projects.
Sewer Filtration Systems
(Improve Stormwater Runoff Quality)
Local Bioretention Filters
(Improve Stormwater Runoff Quality)

19. Recommended 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”
Recommended Locations
• See large maps for locations
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
Recommended Locations
• See large maps for locations

20. Recommended 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
• Strategically keeps more water on the surface
Recommended Locations
• See large maps for locations
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)
Recommended Locations
• Where opportunities exist

21. Recommended Solutions
CONVEYANCE CONTROLS
Adding New Sewers (Twinning)
(Controls Basement Flooding)
Replacement of Existing Storm
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
Recommended Locations
• See large maps for locations
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
Recommended Locations
• See large maps for locations

22. Recommended Solutions
CONVEYANCE CONTROLS
Stormwater Tunnel to New Outfall
(Controls Basement Flooding)
Underground Oversized Storage
(Controls Basement Flooding)
Description
• Increase a portion of sewer pipe by replacing the old sewer with a
larger ‘super-pipe’ to provide temporary storage of water
• Once sewer capacity is available, water is gradually released
What Does it Involve?
• Road excavation within City limits
• Removal of old sewer and replacement/placement of new sewer
and restoration of road and boulevard
Recommended Locations
• See large maps for locations
Description
• Relieve the capacity of the sewer system by adding a new deep
sewer pipe to divert a portion of flow to a new outfall
What Does it Involve?
• Tunnelling deep underground with trenchless technology to avoid
traffic disruption associated with normal open trench excavation
• Periodic access shafts requiring temporary road excavation with
City limits during construction
• Construction of a new storm outfall to watercourse, underground
storage facility, or surface pond facility
Recommended Locations
• See large maps for locations

23. Recommended Solutions
END-OF-PIPE CONTROLS
Oil & Grit Separator
(Improves Stormwater Runoff Quality)
Underground Storage Tank
(Controls Basement Flooding & Can Improve
Stormwater Runoff 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)
Recommended Locations
• See large maps for locations
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)
Recommended Locations
• Distributed throughout study area.

24. Recommended Solutions
STORMWATER QUALITY IMPROVEMENT OPPORTUNITIES
• Where soils have high
permeability,
overlapping sewer
projects will consider
Local Bioretention Filters
and Sewer Filtration
Systems.
• Oil and Grit Separators
(OGS) are placed in
highly paved locations.
• There are no
opportunities for new
end-of-pipe pond / tank
facilities due to space.

25. 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
finalization of the preferred solutions.
• The Project File that documents the study’s findings and recommendations is
expected to be available for a 30 day review period in the summer of 2015.
• The City will implement the recommended solutions pending completion of the
Environmental Assessment, future regulatory and budgetary approvals, and
coordination with other planned infrastructure projects in these areas.
Contact Information
For more information on this study, to provide your comments, to be placed on the
project mailing list, or to receive a copy of these boards 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