Casting Pit and Structural Support

Newnan, Georgia

Bonnell Aluminum is one of the nation’s leading producers in custom aluminum extruded profiles.   In order to improve inventory control and reduce operating costs, Bonnell produces its own aluminum stock, melting down scrap metal and then recasting it into billet form in a large casting pit.


After a fire destroyed the existing casting pit and a part of the manufacturing facility, Tiernan & Patrylo was contracted to complete the design and reconstruction of the new casting pit, which consists of three main areas: the casting pit, the access pit, and the sump well. The casting pit is approximately thirty-seven feet deep and rests on a concrete mat foundation that ranges in thickness from three to six feet. The access pit is also thirty seven feet deep and rests on a two foot thick concrete mat foundation. The third sump well extends to a depth of forty feet and also rests on a two foot thick concrete foundation.  In addition, at the center of the casting pit, there is a forty-two inch diameter casing with a two inch thick steel bottom plate that is seventy feet deep. This casing houses the hydraulic cylinder that lifts the cast billets out of the pit.


The pit could not be over excavated due to the proximity of an existing building so Tiernan & Patrylo installed an engineered sheet pile shoring system with three levels of structural wales made up of twenty-four inch steel wide flange beams.  This allowed excavation without undermining the existing building structure.  In addition to the pit, Tiernan & Patrylo is replacing the existing building frames and footings, providing new metal roofing and siding, and repairing the floor slab at the casting department.