Hamilton, ON – The City of Hamilton’s Office of the Auditor General (OAG) has released its report on their investigation into sewage spills that had been leaking into Hamilton Harbour.

The OAG engaged an external forensic engineering expert to conduct an origin and cause and risk assessment investigation of the incident sewage spills and to undertake a peer review of the Hamilton Water investigation and the report by Stantec Consulting responding to elements of the Ontario Ministry of Environment, Conservation and Parks (MECP) Order.

The investigation found the sewage spills were caused by the following factors:

  • The drawings used in the design and construction were incorrect, which resulted in improper instructions being provided to the design and construction teams.
  • The lack of recognition that the cross-connections were being constructed – and were not deemed a significant risk – during the construction process.
  • The physical piping networks and the drawings illustrating them were large, complex, and interconnected, which made it difficult to identify issues once they existed.

The report concludes that:

  • The Hamilton Water response to the spills and investigation into the origin and cause was appropriate, thorough, and in accordance with the industry’s best practice.
  • The MECP Order was reasonable, and the ongoing response to the Order by Hamilton Water and Stantec is appropriate, thorough, and in accordance with the industry’s best practice.

The OAG put forward five recommendations for consideration by Hamilton Water to help support the response to, and mitigate, future spills:

  • Continue with actions outlined in the Stantec report such as:
    • The existing sewer lateral cross-connection program,
    • Existing passive monitoring and complaints-driven processes to find and identify suspected cross-connections and spills.
    • Continue and expand the Risk-Based Proactive Pilot Program in the high-risk central Hamilton combined sewer system and using this program as a launching pad for a permanent System-wide Unauthorized Discharges Removal and Inspection Program.
    • Review and revise these programs over time to ensure they remain a good value as infrastructure is renewed, cross-connections are repaired, and high risk areas are cleared.
  • Use and refine Hamilton Water’s risk-scaled communication and response (for as-yet-undiscovered leaks/cross-connections). As it is likely that residual risk exists that new leaks/spills may be uncovered; therefore, transparency and response planning remain important.
  • Maintain focus on integrating wastewater asset management information across three Hamilton Water databases while moving toward a streamlined and unified asset management data base is prioritized to ensure collaboration and communication between internal City divisions.
  • Consider on a risk-basis, including Hamilton Water and Engineering Services expertise to review City design and construction projects at key milestones and include personnel with optimal and timely expertise being part of projects, particularly those wastewater projects with higher risks of cross-connections, spills, or other community impacts.
  • Continue to evaluate opportunities for improvement on a cost-benefit basis balancing costs to the natural environment and community with policies related to stormwater management and infrastructure investment and operation specific to stormwater management.

Hamilton Water has agreed with all five recommendations and provided management responses.

Quick Facts:

  • The City of Hamilton has 3,080 kilometers of sewer pipes, of which 40 per cent is dedicated wastewater/sanitary, 41 per cent is dedicated stormwater, and 19 per cent is combined.
  • A total of three wastewater spills were reported to the City of Hamilton’s Public Works Committee, one on November 28, 2022 and two on February 12, 2023.
  • On January 18, 2023, the Ministry issued an Order to the City of Hamilton in response to the Burlington Street Spill (on November 22, 2022) and the subsequent Rutherford Avenue Spill (on January 9, 2023)

The three spills investigated in this report and spills of this nature are a concerning reality within many cities across Canada given aging water and wastewater infrastructure. There is no simple solution, however following this investigation, I am encouraged by the actions taken and underway, and I would underscore the importance of implementing the recommendations we have made in this report.” – Charles Brown, Auditor General, Office of the Auditor General


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