Engineered fill is used to create housing lots from land that was previously unsuitable. Out here, in the high plastic mud plane flats, there are slough areas that hold water most (all) years. The small ones are filled with engineered fill and turned into housing lots. No problems, usually. Bigger sloughs are usually reshaped to fit the lots better. The topsoil and/or marginal material is used to create a damn to control the water and fill is used to bring up the lots.
The primary difference between engineered fill and clean common fill is the amount of compaction and the documentation of the compaction. There is an issue with the extent of the engineered filled provided in the lots, and as the design, size, and location of the houses are not known at the time of lot construction, errors frequently occur as to the required lateral extent of the engineered fill.
After the house is put on the lot, the question becomes, was the rear of the house placed in engineered fill or into common fill? Where settlement of the back wall of the house occurs, it is likely that the engineered portion did not extend far enough into the lot.
But how do we prove the boundary of the engineered fill when the difference is compaction at the time of placement? If they used organic or marginal fill, the difference becomes apparent. But if it is good fill, now what?