Flood Management - Toronto and Region Conservation Authority

Flood Management
July 8th Severe Weather Event
Etobicoke-Mimico Watersheds Coalition Meeting
September 19, 2013
Laurian Farrell, P.Eng., MLA
Toronto and Region Conservation Authority
Email: lfarrell@trca.on.ca
Tel: 416.661.6600 ext 5601
Flood vs. Ferarri
and other untold stories!
Estimated Storm Damages (to date)
• Insurance Bureau preliminary
estimates more than $850 Million of
insured property damage
• City of Mississauga anticipates
approximately $1.2 Million in
municipal infrastructure damages
• City of Toronto estimates
approximately $60 Million in operating
& capital costs due to storm
• Region of Peel estimated $550k in
additional waste removal costs due to
the storm and over $500k in damages
to the GE Booth Wastewater
Treatment Facility
The Storm
July 8th, 2013
Documented Erosion
Sites
Priority sites for Flood Remediation *
* Based on Regulatory Storm Event Flooding
How did the rivers react to rainfall?
50-126mm
Rainfall Totals
1-3m Rise
(3-9 ft)
Water Level Rise in Streams
Bennington Heights Drive Erosion
Thompson Ave. Retaining Wall Failure
Black Creek Channel overtopped by 2 ft.
July 8th 2013
Flooded Roads
Surcharged Sewers
Basement Flooding
Critical Infrastructure
Social Media
Fairway at Islington Golf Club
Hwy 427 at Burnhamthorpe
Flooded Rescue Vehicles near Don River
Basement Flooding (Weather Network)
Mouth of Etobicoke Creek – 1 day after the storm
The Feedback
• Are you going to pay for my
damages?
• Do you admit you’re
responsible for this?
• What are you doing to make
sure this doesn’t happen
again?
• Why did no one tell me I lived
in the floodplain?
• No more studies! Do
something!
• Backflow valves don’t work.
• Stop allowing development!
This should not have happened!
Mimico Creek Stream Gauge 02HC033 and Cross Section Locations
Gauge
02HC03
3
Mimico Creek at Bloor St. & Islington Ave.
Cross Section of Design Storm Water Levels
During the July 8th, 2013 storm event, the peak
water level at the gauge exceeded the maximum
value of the rating curve. Peak flow and water
elevation were estimated to be about 190 m 3/s and
115.235 m, which would categorize this event as
being greater than the 100-yr storm but well below
the Regional design storm at this location.
REGION
AL
July 8,
2013 Event
52-YR
YR
10YR
10050- YR
25-YR
YR
BANK
HEC-RAS model cross-section output for design
storms
Design Storm
Regional
2 yr
5 yr
10 yr
25 yr
50 yr
100 yr
Q Total Water Elev
(m3/s)
(m)
402.8
117.1
42.6
113.55
60.7
113.93
74.4
114.23
92.5
114.48
107.1
114.67
121
114.82
Mimico Creek Water Levels for July 7-12, 2013
PRELIMINARY REAL-TIME DATA FROM WATER SURVEY CANADA, ENVIRONMENT CANADA
Etobicoke Creek Stream Gauge 02HC030 and Cross Section Locations
Etobicoke Creek south of QEW
Cross Section of Design Storm Water Levels
During the July 8th, 2013 storm event, this
stream gauge did not record the peak level and
flow of the storm, therefore these were
estimated using a HEC-RAS model run based
on maximum rainfall total in the Etobicoke
watershed (109.6mm). The estimated peak flow
from the model was 475 m3/s which would
categorize this event as being just greater than
the 100-yr storm but well below the Regional
design storm at this location.
July 8,
2013 Event
REGION
AL
100YR
Design
Storm
5025YR
10YR
5YR
YR 2YR
BANK
Regional
2 Year
5 Year
10 Year
25 Year
50 Year
100 year
Water
Q Total Elev
(m3/s)
(m)
1249.4
94.93
134.9
91.19
205.7
91.45
259.7
91.78
335.9
92.36
395.7
92.39
459.4
92.64
Can this happen again?
Peterborough
Hazel
Essex
July 8th storm:
We’re Tweeting
Downtown Brampton Flood
Protection Feasibility Study
Etobicoke-Mimico Watersheds Coalition Meeting
September 19, 2013
Laurian Farrell, P.Eng., MLA
Toronto and region Conservation Authority
Email: lfarrell@trca.on.ca
Tel: 416.661.6600 ext 5601
Project Goal:
To identify options to reduce and/or eliminate
!
flooding during the Regional Storm
(Regulatory).
Etobicoke Creek flows
Spill into historic valley
Backwater from downstream
!
Must not create more flood risks
upstream or downstream
!
Brampton Diversion Channel
•
•
•
•
•
2008 South of CN Rail
Constructed in 1952 by the Etobicoke & Mimico Creek Conservation Authority
600 m long trapezoidal concrete lined channel
22m wide (top width)
Built to convey the 100 year storm
4 bridge crossings
2008 Natural Channel Section
Location of bridges
Why does Brampton flood?
Large Upstream
Contributing
Drainage Area
Highly
Urbanized
(landuse)
Minimal Stormwater
Controls (2yr storm only)
By-pass
starts
here
Flood Risk in the SPA
Frequent
Infrequent
0.5-2.5 m depth of
flooding in
Downtown Core
during Regional
Event
Point at which flow spills from channel
across Ken Whillans Drive
*based on 2012 Hydrology, MMM Group
Location of spill
out of the bypass channel
Flood Risk in the SPA
Depths based on 2012 floodline mapping
1m
3m
2m
2m
Existing Flood Risk & Mitigation Options:
Alternative ‘A’:
Conveyance
Improvements
Alternative ‘B’:
Flood Control
Alternative ‘C’:
Diversions
Alternative ‘D’: Flood
proofing
Alternative ‘E’:
Land Acquisition
Combinations of the
above mitigation must not
EXISTING SPA BOUNDARY
!
increase flood
impacts elsewhere
Preliminary Alternatives:
4. Bridge
Improvements
1. Church Street
Berm
5. Channel
Deepening
2. Rosalea Park
Berm
3. Flood Protection
Landform
6. Channel Widening
7. Valley ReShaping
Engineering Study:
Feasibility Study
Alternative ‘A’:
Conveyance Improvements
Alternative ‘C’:
Diversion
Hydraulic Impacts:
• Can flood levels in SPA be
eliminated or reduced?
• Can the frequency of flooding in
SPA be reduced (e.g., Regional
Storm)
• Are there any upstream or
downstream impacts to risk?
Alternative ‘D’: Flood
proofing
Policy Impacts:
• Will the SPA policy still apply?
Alternative ‘B’:
Flood Control
Alternative ‘E’:
Land Acquisition
Combinations of the above
(permanent vs. non-permanent flood
protection)
•
If it does still apply, can flood
proofing requirements be
reduced?
EA
3-4 Mitigation Options
Evaluate Options in More
Detail:
• Economic Impacts /
Opportunities
• Social Impacts /
Opportunities
• Environmental Impacts /
Opportunities
Engage all stakeholders
including public
3 Concurrent Studies
TRCA/City of Brampton Joint Steering Committee Projects
1
1.
2
2.
TRCA Downtown Brampton Flood
Protection Feasibility Study
City of Brampton Urban Design and
Landuse Study
City of Brampton Project
3
3.
Downtown Brampton Special Policy
Area: Comprehensive Flood Risk and
Management Analysis
Thank you
LAURIAN FARRELL,
P.ENG., MLA, PMP
SENIOR MANAGER, FLOOD RISK MANAGEMENT
& INFRASTRUCTURE
TORONTO AND REGION CONSERVATION AUTHORITY
EMAIL: lfarrell@trca.on.ca
TEL: 416.661.6600 EXT 5601