The 112 feet tall John Day Lock & Dam Gate stood as an icon of our nation’s economic capacity. But at 53-years old it was visibly fatigued putting the entire navigation industry at risk. But thanks to Advanced American Construction (AAC) the complex work of removing the gate and fabricating transporting and installing the new two million pound gate was impeccably executed in an unprecedented 14-week river shutdown.
For its innovation and skill Advanced American Construction received the 2012 AGC Build Washington Grant Award for Construction Excellence.
To facilitate the removal of the existing gate AAC sized it into four 500000-pound sections. Using a 660 ton crane mounted on a flat deck barge crews ensured each individual section of the old gate was removed safely and in a structurally sound manner. Transporting the gate sections required a second material barge several tugboats and an elaborate dolly system – all requiring engineering ingenuity. AAC delivered an in-house design and fabrication of the extensive lashing solution and gear to secure the gates during transport.
Installing and welding in place the new two million pound 90-feet wide x 16-feet deep gate poised several challenges. Narrow access to the location of the gate required each section to be delicately hoisted from 100 feet away by the derrick barge and lifted over the John Day Dam’s bridge – with a boom clearance of a mere 18 inches. During the heavy lifts AAC constantly monitored and counter balanced the heavy lift barge to keep the barge within the 1/2% listing requirements.
All the while the boom was affixed to a floating barge. This non-conventional rigging included non-standard oversized shackles that had to be approved by the manufacturer. Each gate section required fracture critical welding (approx. 10000-feet) to secure it. AAC also replaced the full mechanical drive system which controls the lifting and lowering of the gate by balancing two counterweights both weighing nearly one million pounds.
The inherent instability of working on a barge on a fast-running river in the notorious high winds of the Columbia Gorge presented several challenges that were all overcome by AAC. Said Col. Steve Miles of the Army Corps: “The Corps relies heavily on competent teammates and the construction expertise of professional firms like AAC. We needed you to develop a sound engineering plan that nailed the tolerances quality and safety – and you did it.