It is in fact fracking sand. They are also loading the sand still in brailers into hi cube boxcars at the port too. I am having a hard time piecing together their operating patterns though. Sometimes they will haul out 10-15 frack sand cars at a time with the normal train of pellet cars and corn syrup to DuPont for interchange. Other times they will string together a monster (for that line) 30+ car string of cars and hand it off to the BN either at East Oly or maybe on one of the sidings at the brewery. Most operations seem to be happening in the evening and on Sunday these days.