Engineered fill is what we call the process of placing clay to support small buildings such as "traditional" houses. What is being built is far from traditional. And then there is the wet soil issues, where 0.6 metres of dry high plastic clay is placed and crusted over with a packer. The remainder of the fill is placed. Now what?
At the best, with traditional houses, we expect 2 inch of differential movement. Now a few construction problem/errors, tight basement finishes, and what do we have but houses who do not meet the owners expectations, but are within the expectations of the land developer and geotechnical engineers.