During Port Hope Area Initiative (PHAI) work at the Highland Drive South Ravine, water used to flush excess grout from the construction surface during sheet piling was observed in the coffer dam at approximately 11:30 a.m. on Wednesday, August 6, 2025.
Workers immediately stopped operating the pump to lessen impacts and to implement corrective actions that would prevent additional water from leaving the work area. Water samples were collected and sent for analysis. Mitigation measures have been implemented, such as the placement of additional check dams and sandbags to control water release, and continuous monitoring during the grouting operation to ensure the process water is properly controlled. Work resumed on site on August 7, 2025.
At no time was there a risk to the safety of workers or the public, and no harm to the local environment occurred. Additionally, at no time did the process water enter the lower creek beyond the bypass or water features on adjacent properties.
CNL notified the Ontario Spills Action Centre, and proactively shared this information with the Canadian Nuclear Safety Commission (CNSC).