Results of routine sampling conducted on effluent (treated water) from the PHAI Waste Water Treatment Plant in Port Hope on May 23 showed an exceedance for copper above CNL action level. Results of other sampling parameters were in compliance with limits.
On receipt of the results on May 29, CNL stopped releasing effluent to Lake Ontario and began investigative sampling to determine the cause of the exceedances. CNL notified the Canadian Nuclear Safety Commission (CNSC) of the results and CNL subsequent actions to protect the environment.
Additional testing confirmed the results of an exceedance for copper, with sample results in the range of 13 micrograms/litre. The action level for copper is 5 micrograms/litre. Action levels are an internal threshold set well below the CNSC’s regulatory weekly discharge limit.
The Waste Water Treatment Plant was placed in recirculation mode immediately following the event. All sampling results continue to be monitored until October 2023 and the plant is expected to return to normal operation on July 3, 2023.