Joy Home Builders past 9pm Residential Neighborhood?

In a residential area, builders are allowed to continue to 9pm per Fairfax county police.
Joy Builders had cement trucks lined up and were going to continue past 9pm until police dispatched.  This is just too late from 7am to 9pm.  No supervisor was on duty from Joy Builders on hand? Just subcontractors continuing to pour foundation, dont seem very safe past dark either.