• Tiernan & Patrylo recently completed reconstruction of Bonnell Aluminum’s casting pit and surrounding structure. After an unexpected explosion, reconstruction had to be completed with a strict timeline.

    The explosion destroyed the roof above the casting pit and a portion of the end walls, according to an engineer’s report. The main building structure sustained little damage. There was roof damage in adjacent areas. The roof areas remained structurally sound but not capable of withstanding storm force winds because of broken tension rod bracing. Falling debris punctured the roof in some other areas of the plant. 

    During the casting operation, molten aluminum leaves the furnace and runs down troughs to a “sow pan” and then to the molds, which are set on a hydraulic table above a the pit. Aluminum flows into the molds and becomes “billets.” Water is then sprayed on the billets to help cool and harden the metal. 

    Typically in the event of a power outage, the operator aborts the casting process, stopping the flow of molten aluminum. “Emergency water” flows to clear out the metal from so that the metal does not harden.

  • “The findings of the investigation indicated that there were no violations of any OSHA requirements, demonstrating that we have strong safety systems in place, and that our employees are well-trained and follow those guidelines,” Ellis said in the statement. “This event also reminds us of the importance of focusing on safety every single day.” – Spokesperson at Bonnell

  • 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 replaced the existing building frames and footings, providing new metal roofing and siding, and repaired the floor slab at the casting department.

    Visit the project in our Case Study section here.