Owner maintained carpet entry systems

I have an in patient Hospital project and we are providing roof gardens and access to those gardens. Hooray for direct access to nature! My question in on the entryway systems. We want to encourage people to go outside so these are regularly used entries. Using dirt trapping entry systems in a patient care unit would be unacceptable for infection control so we are looking into carpeted mat systems. I can get the owner to agree to the weekly maintenance but since they clean their own buildings, could I get an exception in line with the schools exception? For the record, we're staying with NC and not moving this project to HC for a variety of reasons.