In Kensington, while repairing one, it was found to be a hollowed out log with iron straps.
Late 80's/early 90's, a main broke near Erie & Torrosdale aves. A big sink-hole formed, took out the trolley tracks, created a traffic mess for a while.
It was repaired, hole filled, tracks repaired, all good.
There are 3 large mains crossing that section. And another promptly ruptured. A massive sinkhole formed, it was there for months. How the engineers would not think to replace/fortify the other two mains is beyond me.
“In Kensington, while repairing one, it was found to be a hollowed out log with iron straps.”
That would be cool if it was from Colonial times; less so if it was recent union work.