As a result of extreme weather and record rainfall in the Northumberland County and Durham Region, storm water collection ponds at the Port Hope Long-Term Waste Management Facility reached and exceeded storage capacity. At approximately 9:30 a.m. on June 23, 2017, water overflowed from the storm water management ponds, then flowed over ground to Clark’s Ditch and Brand Creek, which lead to Lake Ontario.
On discovery of the event, CNL immediately implemented measures to contain the collection pond water, including placing sand bags to divert the overflow water into a storm water catch basin on the site and installing additional pumps to decrease the amount of water stored in the ponds. By 12 noon the overflow had decreased substantially, and by 2:00 p.m. it had ceased entirely.
An independent analysis of water samples collected from the storm water management pond overflow indicated that contaminant levels were close to discharge objectives accepted by the Canadian Nuclear Safety Commission (CNSC). The heavy rain would have diluted the storm water such that contaminant levels in Brand Creek and Lake Ontario are considered to have been negligible.
On June 24, CNL took additional precautionary measures to ensure that no surface water from other sources was entering the storm water catch basin by constructing an earthern berm.
CNL will provide updates on the June 23 event as more information becomes available.