Update on the 2018 discharge in Chedoke Creek

HAMILTON, ON - In July 2018, the City of Hamilton informed the public that it had discovered that one of its combined sewer overflow tanks was discharging untreated wastewater into Chedoke Creek. The City immediately stopped the discharge and began clean-up activities in the area.

Over the past year, the City has been working with the Ministry of the Environment, Conservation and Parks (MECP) to investigate the incident and determine what work may be recommended with respect to further remediating Chedoke Creek.

Hamilton City Council takes this matter very seriously and today is sharing additional information that has become available based on the City’s investigations.

Investigations have determined that the spill was a result of a bypass gate in the combined sewer overflow tank that should have been in a closed position, but was opened to approximately five per cent on January 28, 2014. Despite extensive investigations, the City has not been able to determine why the bypass gate was opened.

Older cities like Hamilton often have a combined sewer system where a single sewer system collects and handles both the storm water runoff and sanitary sewage directly from households. The discharge into Chedoke Creek was a combination of storm water runoff and sanitary sewage.

The City estimates approximately 24 billion litres of storm water runoff and sanitary sewage was discharged into Chedoke Creek during the time that the gate was open. This represents approximately four per cent of the annual volume of flow to Hamilton’s wastewater treatment plants.

In response to the discharge, the City has taken a number of actions toward addressing the impacts from the discharge. These actions include:

• Completing enhanced inspections of all combined sewer overflow facilities and an inventory of all critical valves and control points to ensure operations of these facilities are working as designed.
• Review and revision of the procedures that inform the City’s response in the event of a spill.
• Chedoke Creek is an urban watercourse, which means it collects storm water runoff and discharges from the City’s combined sewer overflow tanks during large storm events. Public Health Services does not recommend using the urban watercourse linked to Chedoke Creek for secondary recreational purposes such as canoeing or fishing. Warning signs are posted at public access points near the water’s edge, and indicate a public health warning not to come in contact with the water. These signs will remain in place indefinitely.
• Retaining a licensed external qualified consultant to review the environmental impacts of the discharge and make recommendations around the most effective mitigation and remediation efforts in the Creek. This work has also been peer-reviewed by a second consultant. At this time, the consultants agree that more investigation is required.

Since this came to the attention of the City, staff have continued to monitor water quality in impacted areas of Chedoke Creek. The monitoring demonstrated substantial improvements in water quality conditions within weeks of stopping the discharge and odours also dissipated quite quickly. Sample results show a dramatic decrease in E.coli levels for the parameters tested, and the results were similar to the levels before the discharge within weeks of stopping the discharge.

Quick Facts:

• The Main/King combined sewer overflow tank is located in Cathedral Park at 707 King St W
• The City reported the discharge to the MECP’s Spills Action Centre on July 18, 2018 and has been working with them in their investigation.
• The MECP issued orders to the City under the Environmental Protection Act. The MECP also forwarded the file to the Investigations & Enforcement Branch (IEB).  This investigation is ongoing.
• The City completed surface cleaning in Chedoke Creek in summer 2018 to remove “floatable material” in the area.
• Combined sewer overflow tanks are used throughout the system to protect the environment,  public and private infrastructure, and properties (such as basements) from sewer backups, surcharges and overflows during severe wet weather.

Chedoke Creek is an urban watercourse that has been historically and is presently the receiving body for storm water, combined sewer discharges, and two of the City’s combined sewer overflow tanks, which are designed to discharge combined sewage during large storm events. There are several urban watercourses in Hamilton, which are the collecting water body for storm water runoff, and discharges from the City’s combined sewer overflow tanks during large storm events.

At this time, the City is continuing to work with the MECP to determine what impacts remain in Chedoke Creek due to the discharge, and what work, if any, is required for remediation/mitigation.

City staff will provide updates to Council and the public regarding the MECP investigation as they become available.