Wondering how everyone else handles this situation.?ÿ My company recently started doing more caisson layouts, which is easy enough.?ÿ Although I'm running into a problem when they want us to go back and as-built the caissons once they are finished and filled with concrete, for instance let's say the caisson is suppose to be 36" diameter.?ÿ Now if the top is formed, no big deal.?ÿ My problem are the ones that aren't formed and the concrete measures roughly 48" x 55", for a 36" caisson.?ÿ I know that the top of the ground has caved in a little and there is a mushroom effect for the top of the caisson.?ÿ As I see it there is no way that I can say that the caisson is within 3" of plan location.?ÿ Just wondering how others deal with this situation?
Are there bars sticking out of the caisson??ÿ
I have done some with the rebar sticking out, which at that point I know to shoot the rebar and do intersections to determine the center.?ÿ my main problem is when there is no rebar and just concrete.?ÿ I have in the past gone through and set mags at the plan centers and let the contractors and engineers determine if the caisson is within tolerance.
We have done it a couple different ways.
1) Stake out the PLAN center and let them decide, or
2) Locate enough of the exposed concrete to "calculate" the center of the caisson and then compare that to the PLAN location but make it very clear the centers are calculated based on existing conditions of as-built information (or something like that).
