It will receive them, the system they are on is P25 phase 1. Just make sure to get another antenna besides the stock one.
But before getting the HP-1, Consider that they and any department running P25 can always upgrade their systems to Phase 2 and then the HP-1 will do you no good. For Phase 2 that is.
Loudoun County currently uses the P25 system but on a phase 2 level. Only scanner that cover's that are the GRE PSR-800 or the new X36 HP models currently being offered by Uniden.
Also, remember that more and more Counties are changing their radios systems out and are getting grants for the new APCO P25 standard systems from the Government so most are looking to go with P25 systems over others and sales companies are starting to quote the phase 2 side to newer municipalities looking for these systems.
Either way for now, you will be able to hear a bit with the HP-1 depending where you are in Va.