Thanks for looking up that STB link.
At the time of closing the phosphorus plant was owned by Rhodia Inc. And a bit of history.

The Silver Bow Plant previously manufactured elemental phosphorus, from at least 1986 until 1996. Elemental phosphorus was used by other manufacturers to produce fertilizer, pesticides and food grade phosphoric acid. Elemental phosphorus waste, however, is known as a “hazardous” waste under RCRA, in that it is ignitable, since it can spontaneously ignite when exposed to air, posing a serious threat to the environment and public health. In 1996, the Silver Bow Plant was put into “mothball” status, and was closed in 1997.

So after 1997 there would have been little if any traffic from that source. I was under the impression that most of it went out by UP anyway.