Even with all the development, Con-Rob is secluded, but easy to get to from I-66 and several other roads. But it's not heavily patrolled by the local PD, either, since it's in the Western District for PWPD, and they've got a lot more to keep them busy elsewhere. So... yeah, these guys show up still. A bunch of arrests will slow it down for a few weeks, but they'll be back.
Call it in, and let the cops handle it. Happens enough, they'll decide that if bikers are there, it's time to leave.