While you're going after the last bomb in the Trail of Our Dead mission you'll go through the large room that's under construction and has glass all over the floor and trip mines. You should know this well from the USS campaign, though the area was on fire the last time you were here. All you really need to do is WALK through this area, avoiding all of the glass, and obviously the trip mines, until you reach the center of the room and deactivate the bomb. If you want to run, play Recon and max out your silent run skill, otherwise take it slow. Your teammates shouldn't set this off, but if they do just kill them prior to trying the achievement and do it solo.