We had positive results of a compression test with an irregular (Q3), but sudden planar failure at 20 taps. We performed 3 extended column tests, 2 had no results, but it took little effort to pull off the entire column (see video). The 3rd test we undercut our column by 10 cm and the entire column popped out onto us. This was at first a surprising result, but was similar to isolating the weak layer in a PST. The slab was quite dense so we are assuming that the column test energy was not reaching the weak layer.