Alright im gonna guess.
the lab exploded after you completed the game, and Glados said your mind has been saved or whatever, im thinking this was before the combine came, and more around the black mesa accident. one of the pics had test room 7 in ruin, and the aperture science lab had all this advanced stuff, who wants that stuff? the combine. whose going to stop them? Gordan freeman. whose going to help him? Chell. she most likely died after the explosion, and was cloned by Glados because Chell is truly a clone.
i think its going to be EPS 3 is going to be in the ruins of the Aperture science lab
