In a 50 feet continuous footing, if we encountered with 12 feet length of sand fill (SW/SP) in the center of the subgrade, what would be your recommendation to stabilize the subgrade in this location.
The depth of the sand fill is not sure, but it is approximately around 10 feet deep.

Suggestions are greatly appreciated.

Thank you.

couple of feet of undercut and some select backfill material with tensar fabric, (whats the width?)