Owned by Lehigh Hanson, Inc. (LHI), the Bridgeport Quarry is among the company’s largest and most technically advanced aggregate facilities in North America. In addition to state-of-the art technology and environmental controls, the facility has comprehensive waste minimization, pollution prevention and recycling programs in place that focus on first minimizing any waste and then recycling it to the fullest extent possible. In fact, in February 2012, the Quarry was recognized for its environmental efforts by the National Stone, Sand and Gravel Association (NSSGA) by winning its top award, the Environmental Excellence Gold Award. The NSSGA’s awards program was created in 1992 to provide national recognition for aggregate producers that meet and exceed technical, environmental and regulatory requirements.
In order to access the other side of the quarry under existing railroad tracks, LHI proposed blasting two 30 foot tall tunnels through a 100+ foot tall wall of limestone. There was concern that the exposed face of the limestone wall would deteriorate over time causing debris to fall and potentially injure workers and/or damage equipment residing close to the wall. It was decided that a canopy extending out from the tunnel would be installed to provide protection for workers and equipment. The traditional approach is to utilize large steel I-beams and corrugated steel sheets as lagging between them, but this option is both costly and time intensive so an alternative was discussed.
As a solution, four 41'-6.5" x 29'-8" BridgeCor® 63S Single Radius Arches, 30 linear feet in length, were installed in the tunnels as outfall protection canopies. The structures had a hot-dipped galvanized finish with the portion within the tunnels shotcreted to seal any gaps.
Numerous challenges presented themselves during all phases of the project. Initially, limited design criteria, structure geometry and geotechnical recommendations were unavailable so many assumptions were made. There was considerable coordination back and forth between Contech and J.S. Redpath Corporation (JSR), the contractor on the project, to finalize the structure and meet client expectations. Due to the application being a free standing structure, rather than a buried structure, additional design considerations had to be factored into the structural analysis. These additional parameters lead to structural challenges, such as overturning from the wind load, and resulted in a higher than expected gage and more robust foundations. Due to the versatility of the product, these challenges were met and exceeded.
JSR selected Contech Engineered Solutions because of its ability to provide a turnkey solution. Contech provided: (1) preliminary consultative services to aid in structure selection, (2) cost analysis to assist with the contractor’s bid and LHI's budget, (3) design services for the structure and foundation, as well as (4) assembly services to construct the arches in their final location. Overall, it took 14 days on-site to install and assemble the four BridgeCor plate structures.
"Working with Contech on the design, manufacturing and assembly of four BridgeCor portal canopies proved to be a great project decision," stated Kellan Osborne, Project Manager, with JSR. "From preliminary structure design through structure assemblies, Contech’s customer service, product and installation were to the highest standards. We look forward to teaming with Contech on future projects."