Geotechnical Engineering

Dr. Denise Leahy describes her first job, working in a geotechnical laboratory at the massive La Grande hydroelectric project at Baie James. She was very excited to start field work, but was devastated to learn that, due to security issues, women could not work outside the laboratory. She describes being on a work site with 1000 guys and 100 women as "a learning experience". Eventually she and her supervisor realized that, after putting on the required Personal Protective Equipment, no one could determine her gender and she got out on site.

Geotechnical engineer Kwan Yee Lo describes his work on the intake and discharge tunnels of the Darlington Nuclear Plant, the largest nuclear power plant in Canada. He worked with a student, Dr. Ogawa from Japan, to predict the in-situ stresses and time-dependent deformations of the intake tunnel during its construction in 1983. The predicted values matched the observed values so well that, when constructing the discharge tunnel in 1985, it was deemed unnecessary to take boreholes in the lake or use extensive instrumentation, generating major cost savings. The intake tunnel cost $11.7 million, and the discharge tunnel, which is twice as long, cost $13.5 million.

Geotechnical engineer Peter Lighthall recalls the 2014 failure of the Mount Polly tailings dam in British Columbia, which released over 12 million cubic metres of water and tailings into a creek and, eventually, into pristine Quesnel Lake. This major upset for the mining industry triggered a review of all tailings dams in British Columbia – which "greatly increased the amount of available work for independent reviewers like me". The next year, in Brazil, a tailings dam failure released 40 million cubic metres of tailings that travelled 600 km down a river to the ocean, wiping out communities and destroying the environment.

Geotechnical engineer Dr. Denise Leahy describes her post-secondary education at Laval and the Institute for Geotechnique in Trondheim, Norway. Her first engineering job was as a technician at the La Grande hydro-electric dam at Baie James, where, sue to security issues, women could not work outside the laboratory. After completing her PhD, she took a job at Geocon, an affiliate of Lavalin, where she was mentored by Lech Brzezinski, Getahun Haile, Heri Major, Benoît Demers and Les MacPhie. Much of her work involved the inspection, maintenance and restoration of mine tailings dams and she describes initiatives to consider acid mine drainage prevention and seismic loading for these structures. She describes initiatives to improve the quality of geotechnical engineering in Quebec, and her interactions with the Canadian Geotechnical Society and the Canadian Dam Association. She recalls the transition to computer-aided engineering, particularly the switch from manual drafting to AutoCad. She offers advice to high school students considering an engineering career and newly graduated Engineers-in-Training.

Geotechnical engineer Kwan Yee Lo decided upon graduation in 1957 to do graduate research in soil mechanics at Imperial College London. His Masters of Science work was supervised by Professor Skempton, with Dr. Robert Gibson and visiting Professor Davis from the University of Sydney contributing significantly. In October 1959, he started at the Norwegian Geotechnical Institute, where he essentially was an assistant to Dr. Bjerrum there. He was encouraged by Cam Kenny, later Chair of the University of Toronto Civil Engineering Department, to emigrate to Canada, where he started working for Acres in 1961. His work there included design of the inlet and outlet structures of the Winnipeg Floodway. He then moved to the Ontario Department of Highways, where he tested a full-scale embankment to failure. He joined the University of Laval in 1965 and subsequently, in 1970, Western, where he worked in the areas of tunnels in soil and rock. His many projects included investigating distress at the Thorold Tunnel below the Welland Canal, which led to major changes in the approach to tunnel design in rock. He designed the intake and discharge tunnels at the Darlington Nuclear Plant – the in-situ stresses and time-dependent deformations predictions for the construction of the intake tunnel were sufficiently accurate that it was deemed unnecessary to drill boreholes in the lake or install extensive instrumentation for the discharge tunnel, realizing significant cost savings. He also worked on the Niagara Tunnel from Niagara Falls to Queenston and the Billy Bishop Airport Tunnel in Toronto. He and his graduate students developed means to strengthen clays using electrokinetic forces. He also contributed significantly to the Ontario Hydro (now Ontario Power Generation) Dam Safety Program, developing innovative methods to quantify the safety of 151 dams constructed before the Second World War.

Geotechnical engineer Peter Lighthall is a third-generation civil engineer who studied at the University of British Columbia, graduating in 1971. His first job, for BC mining firm Placer Development, involved construction of a tailings dam to impound mine waste for a new mining operation. Earle Klohn, principal of the firm Klohn and Leonoff, was the principal designer. Two and a half years later, Lighthall was hired by Klohn and Leonoff, where worked on a number of overseas projects, in Kuwait, Maine, Poland, Minnesota, Utah, the Soviet Union, New Guinea, Chile, Peru, . He then spent a year earning a diploma from Imperial College of Science and Technology in London, and a Masters degree from the University of London. He returned to work and the Klohn and Leonoff head office in Richmond, and by the mid '80s was Manager of their Mining Division. In 1995, he moved to AGRA Earth & Environmental, and in 2008, after "retiring" he took his first job as an independent consultant. He describes various techniques used to construct tailings dams, including some that created dangerous structures, and recounts serious failures in British Columbia, and Brazil between 2014 and 2019 that caused widespread environmental destruction and human fatalities. He also advises new graduate Engineers in Training to "get out in the field, to see how things really work."