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 part of the manufacturing facility, Forza Group was contracted to complete the design and reconstruction of the new casting pit. It 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, at a depth of seventy feet. 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. Therefore, Forza Group 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, Forza Group is replacing the existing building frames and footings, providing new metal roofing and siding, and repairing the floor slab at the casting department.