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Superstar
Originally built in the 1950s, the underground cables located between our Esplanade Transformer Station (TS) and Terauley TS are reaching their end of life and will be replaced to ensure that we continue to energize the city’s most crucial institutions. The map below shows the tunnel route selected for the new cables through the Class Environmental Assessment (EA) process completed for the project in June 2020. The new underground tunnel will run between the stations at a depth of approximately 25 metres below ground in bedrock within existing road allowances.
In addition to the installation of the new tunnel, new tunnel access shafts will be constructed at both Esplanade TS and Terauley TS.
From: https://www.hydroone.com/about/corporate-information/major-projects/power-downtown-toronto
They are starting the excavation for the tunnel at The Esplanade & Lower Sherbourne this week.
About a decade ago they dug a similar tunnel from The Esplanade TS to the TS at Front & Windsor - there was really very little sign of it being dug.