a helical outrigger apparatus attached to an underpinning drive assembly for exerting an auxiliary anchoring force upon the underpinning drive assembly while sinking piers , pilings , screw - type underpinnings and the like . the piers , pilings , etc . are used to lift and support new and existing structures . the anchoring force is used to supplement a principal anchoring force provided by a dead weight of the structure . the helical outrigger apparatus fastens to a pier bracket which supports the underpinning drive assembly during operation . the helical outrigger apparatus includes a screw - type helical anchor that is sunk into the ground temporarily . the apparatus includes at least one outrigger fastened to the pier bracket . multiple helical outriggers with anchors may be located evenly along the drive assembly . each outrigger assembly includes an arm that is pivotally and telescopically moveable to facilitate connection between the pier bracket and the corresponding helical anchor .