One very early morning this past January on an exceptionally frigid -25c day, I met up with some local drainers at Gargantua’s outfall to finally put my curiosity at rest about this system. I had been provided the impression that the drain was extremely long (just short of 6km), and pretty boring so it dropped lower on my ‘to do’ list, but with January being so cold, I figured it was the perfect time to spend a few hours under the city sheltered from snow and howling wind. Gargantua is located in the Northern end of the city in what would be an otherwise lame part of Toronto you wouldn’t normally find yourself in, unless you happened to driving through or if you happen to live in the area. Gargantua is a buried creek, called Wilket Creek under the surface of the existing dry trail running north up Willowdale proving drainage for the area. Wilket Creek was actually known as Milne creek until the 1950's after Alexander Milne who first settled the Northern end of the Valley. The name Wilket Creek originally refered to a tributary of the East Don River almost three miles further North.
Upon first entering gargantua at the outfall I was struck at the dimensions of the just one of the tunnels. Twin concrete boxes, having the dimensions of a small pedestrian walkway run side by side from the outfall upstream for almost a kilometer before an interesting box type opening briefly appears where you can gain access to the other tunnel. I’m not quite sure why these two tunnels run this way, but I suspect these prefab pieces were merely just dropped into place and were more economical then using one giant box.
Read more here :http://www.ntropy.us/archives/25