Sometimes it becomes necessary to excavate contaminated soil underneath a  foundation wall or basement.  When this happens under-pining the foundation with a solid concrete footing is needed. The footing must be supported on virgin ground.  pouring   concrete into a form, forming a block of  concrete resting on virgin ground.

The local Building Inspector must inspect the forms as each day and pour takes place..

A typical underpour footing consist of 3 yards of concrete. The forms must remain in place for at least twodays before the form can be removed. The process can be repeated as the excavation moves down the wall.