Sarnia has tons more smokestacks and firestacks than Hamilton. It's a different kind of industry though, Hamilton has the heaviest and oldest industry, it's just plain massive and it's really concentrated around the harbour. The Chemical Valley spreads out for 20 miles or more. There are over 60 chemical plants plus all the power generation in the Sarnia area but many are on isolated parcels of land surrounded by fields.
You wouldn't want them all together though. In the mid 1990s I witnessed a lightning strike on a giant oil tank as I was coming over the Bluewater Bridge after a night out in Detroit. I could still see the massive plume of fire when I arrived home in Port Lambton, about 40 km away. I couldn't imagine what would happen if a fire like that spread.
Another anecdote: I used to work at Union Gas, a ways from Sarnia but still related to the petrochemical industry there. There were massive compressors that pumped gas into empty oil wells for storage. The largest jet engines in the world (at the time) were used to pump the gas underground. They were so loud you would go deaf instantly if you went in without ear protection while they were running. When they shut down, the excess gas had to be blown off, it would send a stream of gas over a hundred feet in the air and let out a sound you wouldn't believe. I was told enough gas was released to heat a fair sized town for a year. We all firmly believed that if the place blew up it would take out half of southern Ontario.
Coming someday: new stuff from Rochester, NY; Hamilton; Toronto; Goderich, ON; Wheatley, ON; and Cobourg, ON.