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July 18, 2019

Port Granby

As a result of torrential rainfall causing flash flooding in Southern Ontario on July 17, 2019, surface water overflowed from catchment areas at the Port Granby Project waste management sites, located near the Lake Ontario shoreline in Southeast Clarington. Berms used to contain the water became inundated and were breached, resulting in overflows.

Upon discovery of the overflows at approximately 7:00 a.m., CNL’s contractor took immediate action to redirect the water by pumping it to on-site storage tanks and ponds, and to deploy additional sandbags, which effectively stopped the overflows. The berms were repaired that same day.

Based on observation of the overflow and the size and extent of the flow paths, it is estimated that 80 – 150 cubic metres of surface water flowed to the lake, about the volume of water in a backyard swimming pool.

At no time was there a health or safety risk to workers or the public. Water samples were taken at the catchment areas and have been sent to an independent laboratory for analysis. The results are expected to show that the effect on the environment was negligible because the surface water had been diluted significantly by the heavy rainfall.

CNL proactively notified the Canadian Nuclear Safety Commission and the Municipality of Clarington of the overflows.

A fact-finding investigation by CNL is underway, and this disclosure will be updated if new information becomes available.