So when I tried to destroy the Silver Rush I placed a ton of mines in front of the door before I'd kill the guard outside. However, everytime I'd place a couple of mines... when I walked away the damn things would go off. So how can I throw down like 5 mines without them going off when I walk away from them?

If they're near a npc they should detonate automatically hostile or not.
Just place them at choke points stand back and shoot someone then hide where there is no direct LOS to you.
The npc's will rush you and set the mines off, without you having to get near.

whats your explosives skill level? Never had trouble placing mines on a level 32 explosives. I did have trouble disarming mines on level 16 though. I would say you want level 32 explosives minimum. Which system are you playing on?