In 1939, the U.S. Army Corps of Engineers’ LaGrange Lock and Dam was completed on the Illinois River near Beardsville, just north of where the Illinois meets the Mississippi. It’s a key shipping point for commodities flowing to all points south on the Big Muddy.

After 81 years of service with only minor repairs in 1986 and 1988, the 600-ft-long lock and dam was past due for a refresh when AECOM Shimmick began the Corps’ $117-million rehabilitation last year.

“The LaGrange Major Rehab/Major Maintenance is the single largest construction contract ever executed by the Rock Island District,” says Col. Steven Sattiger, commander and district engineer of the USACE Rock Island District. “In the last 20 years, only one other Rock Island project exceeded the magnitude of the LaGrange project, but that project was split into multiple contracts and took nearly 10 years to execute, unlike LaGrange, which was substantially completed in a single construction season.”

Frequent flooding and temperature extremes combined with high usage resulted in significant deterioration of lock concrete and the decline of mechanical and electrical systems’ performance and reliability. The locks even had grass growing through the aged concrete.

AECOM Shimmick was tasked with dewatering the lock, removing its lock face, installing new precast panels and rebuilding the lock face with embedded armor plates for better durability.

“It was going to be a very difficult job in the way that the Corps set it up,” says Bob Wheeler, project director who also worked on the Olmsted Lock and Dam. “Before the summer shutdown, we kept the lock open and just performed construction activities around the lock, which can interfere with river traffic. It’s really hard to get things done that way.”

Work began in July on a 90-day lock closure and dewatering, but AECOM Shimmick was supposed to get several closures throughout the two-year project. The flooding of spring and summer 2019 meant that Wheeler and his team needed to compress work activities into a reduced, single closure window of 90 days from July to October 2020. With such a tight window, Wheeler said he knew it was going to be “incredibly difficult.”

The AECOM Shimmick team would need to install new miter gate anchorage points and new programmable control systems for opening and closing the miter gates. Since the site floods so much, the Corps wanted to replace traditional hydraulic cylinders with new technology.

“When they go underwater, [hydraulic cylinders] tend to leak and that’s going to become a problem,” Wheeler says. “It’s a cost and maintenance issue.”

Instead of hydraulic cylinders, the new lift mechanism uses rotary actuators with spindle technology that hadn’t been used in the U.S. for locks before. It’s technology that the Corps adapted for locks from submarines that use spindles to open and close hatches and torpedo bays.

Rotary actuator manufacturer Moog provided detailed instructions for their installation. The implementation needed to be exact for the actuators to work properly.

“They take up a much smaller footprint than the traditional cylinder,” Wheeler says. “When we were measuring the shaft and the spline that the rotary actuator fits on, it had to be within ten-thousandths of an inch—basically in a lock and dam like this, if it’s within an eighth, you’re good.”

Laser scanning was used to pinpoint the installation points of the actuators.

Heavy equipment within the tight footprint of the riverside lock and dam included a 300-ton crane on the land side, a 300-ton crane upstream and a 300-ton crane downstream of the bulkheads and the lock. A 150-ton crane was located on a barge outside of the riverside wall and two 60-ton cranes down in the chamber. On the land wall there were two 130-ton cranes and another 60-ton crane. These cranes were used to place the lock armor as well as new concrete for the lock walls, which the cranes placed using buckets.

AECOM Shimmick’s crews logged 200,000 worker hours in three-and-a-half months. Coordination and communication of heavy equipment, at peak, included 286 personnel working six 10-hour double shifts in the lock chamber, which is 600 ft long and 110 ft wide.

“We were working from both sides of the lock down the bottom of it,” Wheeler says. “Both sides at the same time. It’s been remarkable. We have a great planning system that we preplanned all of this stuff with. It’s similar to lean, but a lot more focused on getting the field and craft workers into it and giving their feedback every day.”

Underwater construction subcontractor JF Brennan out of La Crosse, Wis., provided the marine plan and the divers. Wheeler says they had to dive on the bulkhead slots, which had to be cleaned out and removed. All of the tainter valves had to be rehabilitated as well. The 1939 dam had a fixed weir used to dredge and clean it out. Brennan and AECOM Shimmick filled it with concrete so that it no longer functions and won’t be a liability for shipping. The modern cleaning systems were installed with the new control system.

“You just couldn’t put concrete in like you normally do where there’s formwork and just place it within three screen lines and finish it. It had to be very exact,” Wheeler says. “Then the structural system that went from the anchorages was in the concrete. We cut it out and then we drilled roughly 6 feet down with the anchors, put the structure in and then put this sparkline shaft in and that bolted to the structure and then the rotary actuator over that. It was really like machining—work you’d usually do in a power house, but out here in the middle of a lock.”

Despite the tight 90-day window to do all of the lock work in the dry, AECOM Shimmick got the project completed on time and the Illinois River has been open for barge shipping since mid-October. Work on five of the eight locks and dams along the Illinois River has been completed.