First row of panels and tiebacks complete. Last sequence of panels for second row is underway.
Each panel is hand trimmed to the correct dimensions to provide support to the full width of the footing.	View of excavation nearing completion. Air track drill provided by Crown Drilling is in the foreground.

Underpinning

Underpinning involves extending the footings of a building by excavating and pouring concrete in a specific sequence. This can be done to lower floor levels for greater height inside a building, or as in this case, to lower footings to accommodate an adjacent excavation. Because of the depth, tiebacks were required to brace the underpinning against vertical loads.