Host Region: Saskatchewan
February 26, 2021
Lac La Ronge Dam is used to control water levels on Lac la Ronge. The major components of the dam consist of a four bay concrete control structure, a fishway channel, and a 3.3 m high rockfill dam with a relatively impervious core. During a routine inspection of Lac La Ronge Dam in June 2017, depressions and cracking were identified on the embankment crest. During the following investigations, a cloudy discharge was observed downstream, indicating material movement out of the embankment core. Temporary repairs were completed to reduce flow through the embankment and reduce the potential for piping. Permanent remediation was planned and initiated in June 2020.
In June 2020, reservoir levels were rapidly increasing due to wet conditions on the basin and it was expected that the core of the dam would be overtopped, increasing the risk of internal erosion. Increased monitoring and additional mitigation measures including a crest raise were put in place to verify the condition and ensure containment of the reservoir. The execution of the crest raise is complicated by the remote site and the lack of sufficient space at the site to accommodate permanent rehabilitation and the crest raise. The risk to the dam imposed by the high reservoir was determined to be more urgent resulting in the delay of the permanent remediation project until 2021.
Through July, the reservoir continued to rise resulting in a lack of adequate minimum freeboard. WSA then elevated the emergency classification from hazardous condition to potential dam failure. This resulted in daily on-site monitoring, satellite camera reviews, and additional mitigation measures. WSA also changed organizational structures for this response to an ICS structure and established an ICP in Moose Jaw and Regina initially. In late September 2020, the elevation of Lac La Ronge at the dam site was declining along with the upstream tributaries. As a result, a step down of the emergency classification was developed to include fewer onsite inspections supplemented by removed data collection.
The potential dam failure classification was officially removed in November 2020.
- Why applying an Incident Command to a Potential Dam Failure is beneficial.
- Learn from a real world emergency response to adjust emergency action plans to be more functional.
- Presenters will demonstrate effectiveness and flexibility of the ICS structure.
Jody leads the Operations and Maintence group of WSA. This group is responsible for the all dam safety actives associated with WSA’s 72 dams including dam safety policy and emergency planning. Along with dam safety, this group is also responsible for the operation and maintenance of WSA’s 9 Major Structures including Gardiner, Qu’Appelle, Rafferty, Grant Devine, Duncairn, Lafleche, Eastend, Val Marie and West Val Marie dams.
Jody has been working within the dam industry for the past 16 years. He received his B.Sc. in Civil Engineering in 2004 and completed his M.Sc. in Civil Engineering in 2013, both at the University of Saskatchewan.
Allison leads WSA’s Dam Safety group and is responsible for the practical implementation of WSA’s dam safety management policy for its 72 dams. This is achieved through the development and testing of emergency action plans, OM&S manuals as well as leading and conducting dam safety reviews and inspections.
Allison received her B.Sc. in Civil Engineering from the University of Saskatchewan in 2004 and has been working within the dam industry for the past 11 years. In her early career she worked in the geoenvironmental consulting industry.
Host Region: Nova Scotia and New Brunswick
March 2021 - more details coming soon