Digging tunnels in Toronto used to be pretty easy, all things considered: dig a hole, put the dirt in a ravine somewhere, and move on. (All the stuff you pull out of the ground has to go somewhere, after all—Montreal built its Expo pavillions that way, if Heritage Minutes taught us anything.)

The problem for Toronto these days is that nothing's as easy as it used to be. A lot of Toronto's soil is contaminated with gasoline and the lead that it used to contain (among just a few of the compounds under your feet). Which means that, thanks also to new environmental legislation, it's no longer possible to just dump fill wherever we want. According to the Globe and Mail:

Today, many downtown development sites sit on partially contaminated land, especially those created by lakefill operations.

“A lot of the clean infill [development] sites in the GTA are gone,” said Gordon Onley, an engineering consultant with Fisher Environmental. “What’s left are the dirty sites.” As another veteran developer observed, “None of the soil I know about in the city is benign. It’s all got history.”

Industry insiders interviewed by The Globe and Mail warn that the huge volumes, combined with regulatory loopholes and intense competition in the building industry, have created a perfect storm. “The soil management issue is a huge can of worms,” said environmental lawyer Janet Bobechko.

Of course, this has implications for building things like subways. Building kilometres of tunnels underneath the downtown, especially under old streets that have had decades of road traffic on top of them (with all the runoff that implies), is now a really expensive proposition. It also has cost implications for the city's condo boom: all of those tall buildings start with a deep hole, after all. Of course, spreading those costs over a few hundred condos starting at a quarter million dollars a pop helps with the economics.

Blog photo by keepitsurreal via Flickr.