After typing Del Monte Plant #3 a few times this evening, I went back to the question I occasionally ask myself: "Where was Del Monte Plant #1"?
This hints it was the San Francisco Cannery at Fisherman's Wharf. The building started off as the Alaska Packer's Association, and its location on Fisherman's Wharf makes perfect sense if the cannery was originally for fish.
The current Del Monte Plant #1 is in Modesto, and the Modesto Bee filmed a video showing what a modern cannery looks like. I suspect the canneries in the 1930's were smaller and had more labor, but were equally noisy!