Public Information Centre (PIC) February 12, 2020 Content Purpose - - PowerPoint PPT Presentation

Tilbury Stormwater Master Plan

Municipal Class Environmental Assessment

Public Information Centre (PIC)

February 12, 2020

Content

Purpose of this PIC Project Team Study Area Master Plan Process Community Café Summary Stormwater Management in Tilbury Existing Conditions Assessment Proposed Design Alternatives Next Steps

Pur urpo pose of

• f t

the he PI PIC

 Provide a progress update for the study.  Discuss the challenges of stormwater conveyance in Tilbury.  Present the existing stormwater conveyance model results.  Present the design alternatives developed to address flooding in Tilbury.  Obtain feedback from residents regarding the design alternatives and solutions.  Break-out tables to discuss design alternatives after the presentation.

Proj

• jec

ect T Team eam

Matthew Link Project Coordinator Chris Thibert Director, Engineering and Transportation Services Mark McFadden Manager, Infrastructure Services Jerry Corso Manager, Public Works South Katerina Oliver Drainage Superintendent Adam Spargo – ERI Project Manager Chris Moon – ERI Project Director and Senior Water Resources Engineer Brad Dickieson – ERI Water Resources EIT Stephen Jahns – RC Spencer Senior Engineer and Project Advisor Dennis McCready – RC Spencer Senior Drainage Engineer

Study udy Ar Area

 The Community of Tilbury

Project Ba Background und

Study Purpose

 The purpose of the Stormwater Master Plan is to identify a set of alternatives to address various flooding issues in Tilbury.

Phase 1 Problem or Opportunity Phase 2 Alternative Solutions

Identify Problem or Opportunity Public Consultation Community Cafe Existing Conditions Flood Assessment Identify Alternative Solutions Identify Impact of Solutions on the Natural, Social and Economic Environment and Mitigation Measures Evaluate Alternative Solutions – Identify Recommended Solution Public Consultation PIC - Review Alternative Solutions Select Preferred Solution Master Plan Report and Notice of Completion Public Consultation 30-day Review Period

WE ARE HERE September 2019

Co Communi unity Ca Café S Sum ummary

• 34 attendees signed in at the meeting.
• 19 flooding questionnaires completed.
• Key areas identified:
• Lyon Street (1).
• Odette Court (3).
• Sunset Place / Thomas Crescent (5).
• Laurentia Drive / Rose Avenue (8).
• Homestead Drive (3).
• Key Flooding Concerns
• September 2018 Flood Event.
• Sump pumps and basement flooding.
• Laurentia Drive – Farm Tile Drains.

1 3 1 4 4 4 3

Co Communi unity Ca Café S Sum ummary

• 34 attendees signed in at the meeting.
• 19 flooding questionnaires completed.
• Key areas identified:
• Lyon Street (1).
• Odette Court (3).
• Sunset Place / Thomas Crescent (5).
• Laurentia Drive / Rose Avenue (8).
• Homestead Drive (3).
• Key Flooding Concerns
• September 2018 Flood Event.
• Sump pumps and basement flooding.
• Laurentia Drive – Farm Tile Drains.

1 3 1 4 4 4 3

MORE QUESTIONNAIRES AVAILABLE TONIGHT

Stormwater Co Conveyanc nce

 What is stormwater?

Surface runoff after rainfall or snowmelt.

Storm sewer Catchbasin Catchbasin Surface Runoff Surface Runoff

Stormwater Co Conveyanc nce

 Stormwater: Surface runoff after rainfall or snowmelt.  Stormwater Collection System is made up of two components:

 Minor System: Storm sewers convey small, frequent storms – Municipal design standard = 5-year storm event.

Storm sewer Catchbasin Catchbasin

Stormwater Co Conveyanc nce

 Stormwater: Surface runoff after rainfall or snowmelt.  Stormwater Collection System is made up of two components:

 Minor System: Storm sewers convey small, frequent storms.

 Major System: Roads and ditches convey larger, infrequent storms – 100-year storm event with max. depth of 0.3 m.

Storm sewer Catchbasin Catchbasin Road Conveyance

Sep 2018 p 2018 Storm E Event

 4 inches (100 mm) of rainfall in 1 hour.  In comparison a 100-year storm event equals 2 inches (52 mm) of rainfall in 1 hour.

52 mm 100 mm

Typi pical Stormwater Co Conveyanc nce

Major System along road Minor System in pipes Storm sewer outfall River / Creek

• Min. 1.2 m

1 2 3

Cha Challeng nges i in T n Tilbur bury

Flat and Reverse Grade Storm Sewers Shallow Outlet Saw Toothed Road Design Trapped Low Points

Major System Minor System

 Very flat topography constrains the stormwater conveyance system.  Minor system: Outlets to Trembley Creek and Mallot Drain. Shallow, channels limit the depth of the storm sewer system. Leads to flat storm sewers with reduced capacity.  Major System: Flat topography requires a saw toothed road profile to provide sufficient grade for drainage. This creates trapped low points along the road where ponding will occur.

1 2 3

Private S Storm S Sewer Co Conne nnections ns

Sump Pump connected to the Storm Sewer Backflow Preventer

Storm sewer at capacity. Pressure head from road ponding

Private S Storm S Sewer Co Conne nnections ns

Not outlet for sump pump. Basement flooding occurs.

Private S Storm S Sewer Co Conne nnections ns

Direct sump pump to front yard to allow alternate outlet during storm events

Private S Storm S Sewer Co Conne nnections ns

Probl blem / O Oppo portuni unity

 The flat topography and constrained outlets have led to a stormwater conveyance system that cannot convey the minor and major systems effectively.  Basement flooding and overland flooding has occurred in Tilbury.  Improvements to the stormwater conveyance system are required to alleviate the flooding.  These improvements vary depending on the cause and extent of

• flooding. No single solution will address the problems.

 The Master Plan process provides a framework to consider multiple solutions under a single preferred alternative. Implementation will

• ccur over the short-term and long-term time scales.

Existing ng Co Condi nditions ns

 Minor System:

 2-year design storm  92 % of storm sewers surcharge.

 59 % of manholes surcharge.  5-year design storm  96 % of storm sewers surcharge.  68 % of manholes surcharge.

 Major System:

 29 trapped low points considered in the analysis.

 9 of the 29 low points are contained within the road and boulevard.  9 of the 29 low points cause ponding onto private property.  11 of the 29 low points cause flooding of buildings or spill through private property  High Priority

Low P Points

Lyon Avenue Flooding of houses. Odette Court Ponding contained in right-of-way.

Alternative 1 Alternative 2 Alternative 3 Alternative 4

Do Nothing Address Overland Flooding Meet Design Standards No Road Ponding

Maintain the Status Quo.

Private Measures:

• Direct sump pumps to the

road to reduce basement flooding.

Targeted Strategies:

• Implement targeted

strategies at the 12 high priority flooding locations to prevent overland flooding of houses.

Private Measures:

• Direct sump pumps to the

road to reduce basement flooding.

Targeted Strategies:

• Implement targeted

strategies at the 12 high priority flooding locations to prevent overland flooding of houses.

Regional Strategies:

• Provide pump stations and

ponds to achieve design standards:

• 5-year storm sewer capacity

Private Measures:

• Direct sump pumps to the

road to reduce basement flooding.

Regional Strategies:

• Provide pump stations

and ponds to facilitate 5- year storm sewer capacity.

• Regrade roads or provide

100-year storm sewer capacity to remove ponding at trapped low points.

Des esign gn A Alter ernatives es

Increasing Cost and Complexity

 Four alternatives developed for the Master Plan.

Des esign gn A Alter ernatives es

Alternative 1 Alternative 2 Alternative 3 Alternative 4

Do Nothing Address Overland Flooding Meet Design Standards No Road Ponding

Maintain the Status Quo.

Private Measures:

• Direct sump pumps to the

road to reduce basement flooding.

Targeted Strategies:

• Implement targeted

strategies at the 12 high priority flooding locations to prevent overland flooding of houses.

Private Measures:

• Direct sump pumps to the

road to reduce basement flooding.

Targeted Strategies:

• Implement targeted

strategies at the 12 high priority flooding locations to prevent overland flooding of houses.

Regional Strategies:

• Provide pump stations and

ponds to achieve design standards:

• 5-year storm sewer capacity.
• 100-year maximum ponding

depth of 0.3 m within the road right-of-way.

Private Measures:

• Direct sump pumps to the

road to reduce basement flooding.

Regional Strategies:

• Provide pump stations

and ponds to facilitate 5- year storm sewer capacity.

• Regrade roads or provide

100-year storm sewer capacity to remove ponding at trapped low points.

Alternative ve 1 1

 Alternative 1: Do Nothing

• Does not address flooding.
• Does not meet design standards.
• Pre-screened – not viable option.

Alternative ve 2 2

Targeted strategies to address key flooding locations:

• Maintain existing storm sewers – not 5-year design

standard.

• Short-Term Solutions (1 to 5 years):
• Implement private side measures – Disconnect

sump pumps and downspouts, direct to front yards.

• Address historic farm tile issues at Laurentia Drive.
• Medium to Long-Term Solutions (5 to 25 years):
• Implement targeted strategies at 11 low point

locations where ponding on the roadway could cause overland flooding of houses.

Summary of each strategy is provided at the breakout tables.

Alternative ve 3 3

Upsize storm sewer network to convey the 5-year storm and contain 100-year storm within the road right-of-way:

• Same solutions as Alternative 2:
• Sump pump disconnections.
• Targeted strategies.
• Laurentia drive farm tile.

PLUS

• Medium to Long-Term Solutions (25 to 40 years):
• Construct approximately 9 km of trunk sewers and

Municipal Drains.

• Construct 6 pump stations / reservoirs.
• Upsize approximately 30 km of existing storm

sewers as part of life cycle replacement.

Alternative ve 4 4

 Upsize storm sewer network to convey the 5-year storm and regrade roads to remove trapped low points and prevent ponding during the 100-year storm:

• Same solutions as Alternative 3:
• Sump pump disconnections.
• Targeted strategies.
• Laurentia drive farm tile.
• Pump stations, ponds and trunk sewers.

PLUS

• Long-Term Solutions (15 to 40 years):
• Regrade roads to provide major system conveyance or provide 100-year storm sewer

capacity.

• Pre-Screened - Very challenging to implement and very high cost.

Des esign gn A Alter ernatives es

Criteria Alternative 1 Alternative 2 Alternative 3 Alternative 4

Do Nothing Address Overland Flooding Meet Design Standards No Trapped Low Points

Prevents Basement Flooding

   

Reduces Overland Flooding of Buildings

   

5-year Minor System Capacity

   

100-year contained with road ROW

   

No Road Ponding at Trapped Low Points

   

Estimated Cost

$0 $26 Million $55 Million >$100 Million  Design Alternative evaluation:

Des esign gn A Alter ernatives es

Criteria Alternative 1 Alternative 2 Alternative 3 Alternative 3

Do Nothing Address Overland Flooding Meet Design Standards No Trapped Low Points

Prevents Basement Flooding

   

Reduces Overland Flooding of Buildings

   

5-year Minor System Capacity

   

100-year contained with road ROW

   

No Road Ponding at Trapped Low Points

   

Estimated Cost

$0 $26 Million $55 Million >$100 Million  Alternative 3:

• Targeted strategies reduce flood risk to

flood vulnerable houses.

• Pump stations, ponds and trunk sewers

allow for future expansion and upsizing

• f the storm sewer network.
• Consideration for future development.
• Capital costs are feasible in the medium

to long-term (25 to 40 years).

Break eak-out ut T Tabl bles

 Four tables to obtain feedback.  Design Alternatives and the 12 targeted strategies are provided at each table.  Opportunity to provide comments on the Design Alternatives.  Opportunity to provide comments on the targeted strategies.  Please fill in a comment sheet so it can be included in the Master Plan report.

Fut utur ure Co Comments a and Q nd Que uestions

• ns

Adam Spargo, B.Sc. Project Manager Ecosystem Recovery Inc. 201 King Street London, Ontario N6A 1C9 Phone: 519-859-0446 Email: adam.spargo@ecosystemrecovery.ca Matthew Link, A.Sc.T. Project Coordinator Municipality of Chatham-Kent 315 King Street West Chatham, Ontario, N7M 5K8 Phone: 519-360-1998 ext 3309 Email: matthewl@chatham-kent.ca

 Take a comment sheet and fill in later.  Contact us directly.

Que uestions ns?