As noted on Atlantic Yards Watch, at about :46 of the video below (and captured in the screenshot at left), workers for the company took a white drum from a van, inspected it, and upended it on the street, discharging a white powdery substance.
What was it? Was this SOP?
As they were wearing no protective gear, it's likely the substance was not particularly toxic. Still, dumping waste material, of whatever ilk, in the street, is hardly an appropriate procedure.
As asked on Atlantic Yards Watch, "Can the ESDC or FCR please tell the community what unknown white power substance was dumped into the street next to 171 unit residential building from a Barclay’s arena contractor? [Are] there any penalties?"
I reached out to the Empire State Development Corporation and Wolkow Braker, which works on major projects like office buildings, schools, courthouses, and museums. If and when I get any amplification, I'll post an update.
What was in the truck?
A longer version of that video (below), via Atlantic Yards Watch, also shows the contractors, beginning at 9:52, taking a cylinder out of the truck and, as shown in the screenshot at right, moving it via handcart to the arena site.
If this is propane, as suspected, it is flammable and explosive, and any commercial motor vehicle over a half-ton requires a placard. As noted on Atlantic Yards Watch, there does not seem to be a placard.