Update on Lisgar District Basement Water Infiltration Investigation - - PowerPoint PPT Presentation

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Update on Lisgar District Basement Water Infiltration Investigation - - PowerPoint PPT Presentation

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Update on Lisgar District Basement Water Infiltration Investigation City of Mississauga June 17, 2014 Agenda Presentation Outline 1. Purpose / Overview of Presentation 2. Background 3. Recap of where we were as of April 2013 4. Scope

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Update on Lisgar District Basement Water Infiltration Investigation

City of Mississauga

June 17, 2014

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Update on Lisgar District Basement Water Infiltration Investigation

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June 17, 2014

Agenda

Presentation Outline

1. Purpose / Overview of Presentation 2. Background 3. Recap of where we were as of April 2013 4. Scope of Additional Work by Consultant 5. Supplemental Work by City Forces 6. Preliminary findings 7. Future Work / Next Steps 8. Other Matters 9. Status of Claims

  • 10. Questions & Answers
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  • 1. Purpose / Overview of Presentation
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Project Title & Date

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June 17, 2014

  • 1. Purpose / Overview of Presentation

 Provide public with a status update  Inform parties of balance of work to completion of study/investigation

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  • 2. Background
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June 17, 2014

  • 2. Background

 Lisgar District experienced basement water infiltration on several occasions over late 2000’s with 187 homes reportedly affected (in total) over this period  City initiated a comprehensive study / investigation of causes (retained AMEC Environment & Infrastructure)  City advanced a variety of proactive measures (primarily maintenance focused)  Class Action suit underway; City’s Risk Management group engaged  Two Public Meetings to-date:

 December 2011  April 2013

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June 17, 2014

  • 2. Background

Three-pipe System in Lisgar

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  • 3. Recap of Where we were as of April 2013
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  • 3. Recap of Where we were as of April 2013

 Public Meeting with residents April 16, 2013

  • Opportunity for City staff and AMEC to describe the activities over 2012 and

associated findings

  • Opportunity for residents to query City Staff and AMEC
  • Provided outline of planned activities over 2013

 Offered outline of some of the speculated changes since initial development of Lisgar Community

  • Climate
  • Groundwater levels
  • Development
  • Changes to homes (walkouts / drainage connections)
  • Aging basements/infrastructure
  • Lot grading
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June 17, 2014

  • 3. Recap of Where we were as of April 2013

 Key Findings

 Surface water reaching FDC system quicker and in greater amounts than would be expected

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June 17, 2014

  • 3. Recap of Where we were as of April 2013

 What we knew in April 2013

Possible Cause / Factor Level of Influence – April 2013 Groundwater Low/Not Applicable GO Station Low/Not Applicable Sanitary System Low/Not Applicable Cross‐Connections Low/Not Applicable Creek Backwater Further Assessment Required as part

  • f Phase 2

Osprey Marsh Pond (SWM) Backwater FDC Inflow/Infiltration FDC Hydraulics FDC Tailwater FDC Depths Lot Grading Basement Construction/ Changes Stormwater to Utility Trench

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  • 4. Scope of Additional Work by Consultant
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June 17, 2014

  • 4. Scope of Additional Work by Consultant

 Second phase of investigation over 2013 focused on data collection to answer

  • utstanding questions; scope of work included:

 Additional monitoring

– FDC, Storm Sewer, Groundwater

 Storm sewer leakage tests  Other

– Review sanitary sewer data – CCTV video – Chemical analyses (water typing)

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June 17, 2014

  • 4. Scope of Additional Work by Consultant
  • Additional Monitoring
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June 17, 2014

  • 4. Scope of Additional Work by Consultant
  • Storm Sewer Leakage Tests
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  • 4. Scope of Additional Work by Consultant

 Review of Sanitary Sewer data, CCTV video, Chemical analyses

− minor − not widespread − City is addressing on an on-going basis

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  • 5. Supplemental Work by City Forces
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June 17, 2014

  • 5. Supplemental Work by City Forces

 FDC System  High Water Protocol  Maintenance and Inspection  Support for Consultant–led activities

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June 17, 2014

  • 5. Supplemental Work by City Forces

 FDC system

 Continued smoke testing of FDC system to identify any remaining cross- connections  Repairs to address identified leakage/infiltration points within FDC system  CCTV (video inspection) and flushing of large sections of FDC system where required

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June 17, 2014

  • 5. Supplemental Work by City Forces

 High water protocol (HWP)

 Ongoing monitoring of weather conditions and storm events; pumps on standby  On site for February 20-21, 2014 rain event (no surcharging occurred)  On site for June 11-12, 2014 rain event (surcharging occurred)

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June 17, 2014

  • 5. Supplemental Work by City Forces

 Maintenance and inspection

 Dredged creek crossings at Doug Leavens Boulevard, Osprey Boulevard, and Alderwood Trail  Continued to monitor creek and Osprey Marsh pond to identify any maintenance needs and assess work completed to-date  Lined select storm outlet channels with Armourstone and removed sediment

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June 17, 2014

  • 5. Supplemental Work by City Forces

 Support for Consultant-led activities

 Storm sewer leakage tests  Creek water level monitoring (equipment and channel maintenance)  Installation of FDC monitoring gauges in deep sewer locations

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  • 6. Preliminary Findings
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June 17, 2014

  • 6. Preliminary Findings

 2013 Monitoring showed:

 FDC system surcharge continues  Downstream FDC capacity may affect upstream system performance  FDC outlets to a storm sewer which surcharges  Osprey Marsh SWM facility water levels show no definitive connection to FDC levels (limited 2013 data though)  No connection to sanitary system’s performance

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  • 6. Preliminary Findings

 Further, 2013 Program showed:

 Storm sewer system clearly leaks into FDC system (utility trench)  Some FDC laterals flow continuously albeit this is minor (based on CCTV); City actively addressing these  Chemical testing confirms FDC water as being very similar to samples taken from storm sewer utility trench, the creek, and the Osprey Marsh SWM Facility (and dissimilar to groundwater samples)

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  • 6. Preliminary Findings

 What we know now (May 2014):

 Based on 2012 data:

– Groundwater – GO Station – Sanitary system – Cross-connections

generally discounted as Not Applicable (N/A) or of Low influence.  2013 Program definitively validated no relationship to sanitary system and cross connections; too few to be of significance

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June 17, 2014

  • 6. Preliminary Findings

 What we know now (May 2014):

 2013 Program proved/validated:

– stormwater is leaking from storm sewers and rapidly moving to utility trenches and

FDC; impact could range from a contributing to primary factor

– surcharging in FDC is widespread and not generally concentrated in one location

(also varies by storm)

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June 17, 2014

  • 6. Preliminary Findings

 What we know now (May 2014):

 2013 Program raised questions about FDC Hydraulics:

– capacity of trunk FDC; due to flat nature of pipe system, impact could be far

reaching

– influence of FDC outlet on system capacity (i.e. storm sewer surcharges) could

impact upstream areas  Over the course of 2013, additional review and consultation with City staff resulted in new factors being added into the mix as potential causes:

– FDC Maintenance (closed system hence clean outs not expected) – Creek Maintenance (outlets and creek cleaned; lands regulated by Conservation

Halton)

– FDC Design (detailed information on design standards to be assessed) – FDC Construction (limited data) – Basement Walkouts (potential to capture and contribute drainage to FDC)

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  • 6. Preliminary Findings

 What we still don’t know:

 Hydraulics of FDC:

– model to validate

 Effectiveness of pumping

– model to validate

 Aggregate influence of various inflows:

– storm sewer leakage – basement walkouts

 Definitive influence of creek and stormwater management facility backwater:

– limited data thus far – field test to validate

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June 17, 2014

  • 6. Summary of Preliminary Findings

New Factor Possible Cause / Factor Level of Influence Notes April 2013 May 2014 Groundwater Low/Not Applicable Low GO Station Low/Not Applicable Not Applicable Sanitary System Low/Not Applicable Not Applicable Cross‐Connections Low/Not Applicable Low Known cross‐connections repaired Creek Backwater Further Assessment Completed as part of Phase 2 Low to Contributing Additional field monitoring in 2014 Osprey Marsh Pond (SWM) Backwater Low to Contributing Additional field monitoring in 2014 FDC Inflow/Infiltration Low FDC Hydraulics Assessment and Analysis Underway (Phase 3) FDC Tailwater FDC Depths Lot Grading Basement Construction/ Changes Stormwater to Utility Trench Contributing to Primary Validated by 2013 storm sewer leakage tests  FDC Maintenance These items were not originally identified at the April 2013 public meeting and have been subsequently considered based on follow‐up analysis and assessment (some have yet to be analyzed). This will be completed as part of Phase 3. Low FDC system flushed since study start‐up; FDC systems are closed, hence would typically only require nominal maintenance Not Applicable to Low Lands regulated by Conservation Halton; work needs to balance ecological impacts. City forces have cleared creek (sediment / vegetation) since study start‐up  Creek Maintenance Assessment and Analysis Underway (Phase 3)  FDC Design

FDC Construction

Basement Walkouts

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  • 7. Future Work / Next steps
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  • 7. Future Work / Next steps

 Phase 3 (Final) of Investigation

 Focus on remaining unknowns  More analytically based (modelling); some supplemental monitoring  Prepare final documentation, and provide City direction for remediation

 Corporate Report proposed early 2015  Public Report will be available also early 2015

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  • 8. Other Matters
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  • 8. Other Matters

 Local Area Development Applications (Infills)

 City is reviewing each with specific objective to ensure no negative impacts from development  No connection proposed to FDC; local foundation drainage via sump pumps; additional surface runoff managed via Low Impact Development (LID) Best Management Practices (BMPs)

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June 17, 2014

  • 8. Other Matters

 Ninth Line Lands Study

 City has initiated a study of the Ninth Line lands, west of Ninth Line to Highway 407  The purpose of that study is to establish preferred land uses use for this corridor, along with general management strategies

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  • 8. Other Matters

 Ninth Line Lands Study

 The Ninth Line Lands Study will need to meet the provisions of the Planning Act and Environmental Assessment Act, specific to mitigation and management of impacts  The Ninth Line Lands are on a separate downstream tributary from the Lisgar District  any development of these lands would not be expected to influence the current risk of basement water infiltration in the Lisgar Area; however the respective studies will inform each other in terms of technical outcomes and management considerations

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  • 9. Status of Claim
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June 17, 2014

  • Damage Claims Filed with the City
  • The City is aware of approximately 187 incidents in the Lisgar Area between

2008 and January 2013; this represents approximately 165 homes that were impacted on one or more occasion; or approximately 2% of all homes in the Lisgar Area

  • Many have submitted a claim with the City’s Risk Management Section seeking

compensation for damages

  • In addition, a Class Action lawsuit has been commenced seeking damages in

the amount of $200 million on behalf of all residents in the Lisgar Area

  • 9. Status of Claims
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  • Damage Claims Filed with the City
  • Like other municipalities, the City’s insurance program does not allow the City

to pay any compensation without evidence of negligence on behalf of the City

  • To date, we have not received any evidence of negligence
  • Unless the legal test for liability against the City is met, there is no justification

for paying out any claims associated with the basement water infiltration in this area.

  • If our continued efforts to find the causes uncover proof of negligence, the City

will then be able to address all reported damage claims

  • 9. Status of Claims
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  • 10. Questions and Answers