Made ground
Also called Fill, Made-up ground
Ground that has been altered by human activity, typically by filling, dumping or reworking with material that is not naturally occurring in that location — demolition rubble, old foundations or uncompacted fill, for example. Made ground is often unpredictable and weaker or less consistent than undisturbed natural ground, so it is a common trigger for additional ground protection or investigation.
In practice
The hazard with made ground is variability rather than weakness as such. A trial pit can show competent fill and a foot two metres away can find a backfilled service trench, a soakaway or a void over an old basement. That is why an average capacity across a site is close to meaningless on made ground: the lift is governed by the worst point under a foot, not by the mean.
Where this comes from: Standard UK ground investigation practice; the risk it presents to plant set-up is what makes it a lift planning issue rather than only a geotechnical one.
Where it matters on site
Most UK urban and brownfield sites are made ground to some depth, so this is the normal case and not the exception. Practically it argues for larger spreading area than the arithmetic alone suggests, for checking what is directly under each set-up position rather than the plot as a whole, and for treating a sudden settlement during rigging as a stop, not as bedding in.