riffian's response jogged my memory, convincing me that I misremembered a few details (and I did).
So I went to Historic aerials - riffian is correct, the building that is now a cosmetics outlet ("Precocious Cosmetics") did indeed receive covered hoppers into this century (some of the aerial photography on HA for that area is not the best). In addition, in an earlier era (1960s) the building to the south of the cosmetics outlet also received rail service; this building now houses a firm that installs commercial overhead doors.
I had originally thought the covered hoppers were parked in the two track "yard" along Gregg St. and that boxcars went to the (then) plastics facility, but no - there was another siding which curved north-east, crossing the siding to the plastics plant (a suspicious radius in the parking lot paving
of Atlantic Power IMO marks its route) which curved past the S.E edge of the building that houses (housed?) Atlantic Power, and this is where the boxcars were spotted. According to HA topos, this line continued further east past Ellios (McCains).