if we are to consider the colony numbers at 70. (lets go with the lower number for the sake of argument). now, lets knock the numbers down by twenty percent based on injury. 56. now lets account for night watch on the walls/ gates, these would not be totally available during the proper working hours. a safe number here given size could be around 12 (two per post, six separate posts).44...those 44 would include CJ herself, Michael, glenn, Tanya, so drop that down to 40 non critical people.

so from tales from my father and brothers work in the concrete yard. it takes roughly 20 separate laborers the better part of a week and the proper equipment to form a bridge beam(think a concrete beam 80 feet long by 10 by10 square). yes. each is person/group of dudes is broken into a "chain" , and they do complete 7-10 beams per week...but that's beside the point. while the colonists are not building bridge beams, they are likely working on a similar type of project. while I do feel like 4 months is a bit of a stretch, I don't completely know that its that far from the truth.