When one complains about the environmental footprint of concrete, the main issue is usually the carbon footprint that comes from the production of cement. But cement is only about 15% of concrete; the rest is aggregate, the rock that the cement binds together. As this slide from The Highland Companies shows, concrete and aggregate is a big part of infrastructure. And just north of Toronto, in Melancthon, the company wants to dig a honking big hole covering 2,316 acres, over 200 feet below the water table, to supply aggregate to the Greater Toronto Area.
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