Kentucky, US-based Sterett Crane and Rigging used a Terex CC 2400-1 lattice boom crawler crane to replace lids on eight anaerobic digester tanks at the East and West Evansville wastewater treatment plants.

“Having sufficient space alone to bring in and assemble the crane was challenging enough,” said Matt Crisp, crawler crane fleet manager for Sterett, about the congested project site at the 34-year-old facilities.

“To remove the massive tank lids that weighed in excess of 250,000 pounds (113.4 tonnes) each, we needed to mobilise a crane that was small enough to fit into and manoeuvre in the tight area while, at the same time, offer the capacity to lift the heavy lids.”

Out of the dozens of crane options from Sterett’s fleet, the one crane stood out for this job – the Terex CC 2400-1 lattice boom crawler crane. With its 440 ton (400 tonne) capacity, the Terex crane offered power to lift the heavy loads, and its Vario-Superlift structure feature proved to be the X-factor Sterett needed to successfully manoeuvre about the site at full load.

The digester tank lids were being removed and relocated for sandblasting and refurbishment. Each tank lid weighed between 258,000 to 274,000 lb (117 to 124.3 tonnes). The weight of the load required the CC 2400-1 crane to be equipped in its Superlift configuration, but as the crane’s body swung the lids into position to lower them onto the concrete cribbing, the Superlift tray had to manoeuvre past site barriers.

“The lids alone were 75 feet (22.9 metres) in diameter, and we had to rig to them at 16 points,” said Mr Crisp. “The plan was to pick the lid at a 91 ft (27.7 m) radius, boom up, move the crane a short distance and then swing the ring into position for lowering it onto the cribbing. However, often a tank obstructed the path of the tray as we swung the load.”

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