Acrow, a leading international bridge engineering and supply company, is pleased to announce one of its modular steel bridges was recently utilized in a successful project to replace sewage system structures under the Santa Cruz River in Tucson, Arizona. Acrow’s bridge provided a safe bypass route for relocated sewage pipes, enabling the efficient excavation, removal and replacement of the existing structures.
The Pima County Regional Wastewater Reclamation Department’s Northwest Outfall Siphon is a dual-barrel sewer siphon that was known to produce high turbulence. This caused a release of corrosive gases, which had begun to produce an unpleasant hydrogen sulfide gas smell in the area. To reduce the turbulence and eliminate the resulting odors, the project team designed two new corrosion-resistant fiberglass-lined structures to replace the existing siphon but needed a solution to maintaining the flow of 15 million gallons per day of wastewater during the rehabilitation work.
While establishing a new route under the river with directional drilling was possible, a far less costly option was to direct the sewage over the river, so an aerial bridge was needed. Building a temporary bridge of traditional construction was also an option, but ultimately, a modular steel bridge from Acrow was selected for the project since it would be a faster, more economical alternative, with far less environmental impact.
Acrow’s bridge, rented to project contractor Hunter Contracting Co., was 270’ long and supported three HDPE pipes. The single-span bridge used two Acrow shoring towers as temporary piers during the cantilever launch of the bridge. The contractor designed, furnished and installed a timber deck.
Delivery of the bridging materials began on March 23, 2023, and the structure was launched a month later. After the installation of the deck and spanning of the pipes, the bypass system was put into service for the duration of the siphon replacement. Acrow’s bridge was de-launched and removed from the site by the end of July 2023.
“The versatility of Acrow’s rapidly installed modular steel components made them ideal for this project,” said Dan Schrager, Acrow’s Business Development Manager, Southwest Region. “In addition to vehicular and pedestrian applications, Acrow’s structures are frequently installed to carry relocated utilities during construction, or as permanent solutions for new installations or to replace aging infrastructure.”
Added Russ Parisi, Acrow’s Vice President, North America, “The strength and expertise of the Acrow engineering team provides government agencies and their contractors with highly customizable, high-quality solutions to keep critical projects on, or ahead of, schedule and within budget. Available for rent or purchase, Acrow’s rugged steel components are well suited for a wide range of permanent and temporary applications.”