The foundation and supporting columns of the Telogia Power Plant’s truck tipper began to shift and settle. Semi-trucks loaded with wood chips back on to the tipper and are hydraulically lifted at an angle to tip the truck and dump the wood chips out of the trailer. Over time, the repetition of this process caused the hydraulic pad and the hinge pad for the tipper foundations to settle in opposite directions. The support columns were 3 to 4 inches out of plumb and had caused a 7 inch gap in the ramp and the approach slab. As the columns continued rotating, the likelihood of them tipping grew. With traffic of up to one truck load every 30 minutes, it was imperative to address the integrity of the columns. Alpha Foundations was called to inspect the structures and determined that the foundations were tipping, causing the angle in the columns. The foundations were 2 feet thick and approximately 2 feet below grade.
Special attention had to be given to the scheduling so that the power company could hold off truck traffic during the repair. Alpha Foundations was given a 24-hour window to complete the installation and return the columns closer to level. On each foundation, six Foundation Groundworks 350 series push piers were installed to an approximate depth of 40 feet. Soil reports showed a shallow layer of very loose material that needed to be bypassed. Four push piers were installed on the outside edge of each foundation and two on the inside edges. Alpha Foundations was able to lift the foundations, causing the columns to straighten and the gap of in the approach slab to close. The Foundation Groundworks 350 retrofit system has an approximate compressive strength of 50 kips per location.