Well, that explains how they handle things before it overflows, not that Donnie had been too curious about it. At the very least, it should probably keep the people on the other side from finding them, but there are clearly more immediate problems.

Donnie's managed to catch up with Fang by the time the other has made his decision, throwing a glance behind them as he hears things start to tumble their way as the bulldozer begins to push through. "Huh-?" is about all he has time for, not knowing what all Fang has in mind although he's in agreement that they need to move.