Has code regarding PVC for drain/septic changed recently for Chicago?

I own a 2 story 4 unit building and recently renovated one of the units. Per code for multi-units, we used all copper throughout, even on the septic and vents. Of the reno, this was by far the costliest part and decimated the budget.

Shortly after, I was walking the neighborhood and stumbled across a new 4 story quad multi-unit being built by Halcyon Homes that was at a stage that was post waste install, pre supply. All of the waste line was PVC, including the vent out the roof. This building would obviously undergo inspection so I was baffled by how this was up to code.

Has something changed to modernize Chicago code? Are there any special exceptions that I'm unaware of that would have allowed this? And more importantly, may I now perform a reno using PVC for the drain side?

 

New pilot.program special permit required