Below the Surface: Trimble Services Puts Clamshell Bucket to Work in Prospect, NY
A first-of-its-kind project for the Trimble Services team combined an 80-ton crane, commercial divers, and a two-line clamshell bucket to perform preventive debris removal approximately 30 feet below the waterline.
Quick Project Facts
đź“Ť Location: Prospect, NY
đź‘· Client: Brookfield
🏗 Services: Crane Services, Underwater Debris Removal
đźšś Equipment: Tadano AC 4.080-1, Clam Shell Bucket
🤝 Project Partners: Hunt Underwater Specialties – Commercial Divers
đź“… Completion: Aug 3-5Â
Taking Crane Operations Below the Surface
Trimble Services recently worked with Brookfield at a hydroelectric facility in Prospect, NY, to perform preventive maintenance by removing logs and wood debris that had accumulated in front of the facility’s trash racks.
The three-day project marked the first field deployment of our clamshell bucket and introduced an entirely different type of crane operation for the Trimble team.
Using our 80-ton crane, the clamshell was operated at an approximately 85-foot working radius and lowered roughly 30 feet below the water surface to reach the accumulated material.
But getting the bucket underwater was only the beginning.
Why Trash Rack Debris Matters
Trash racks serve an important role at hydroelectric facilities, helping prevent floating and submerged debris from entering the intake and reaching downstream equipment. Keeping those areas clear is part of maintaining reliable water conveyance through the facility.
But debris isn’t always sitting conveniently at the surface. Depending on the facility and conditions, material can accumulate underwater and require specialized methods to reach and remove it. Industry guidance recognizes physical removal by crane and the use of commercial divers among the methods used to address submerged debris at dams and intake structures.
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Precision Without a Direct Line of Sight
At the working location, the clamshell had to be lowered into a trash rack opening measuring approximately 60 inches wide. At just 37 inches wide, the bucket was well suited to access the opening—but positioning it approximately 30 feet underwater required a level of precision that couldn’t come from simply watching the load.
The crane operator couldn’t see the debris or the bottom.
Instead, the operation depended on communication between crews above and below the waterline, information from the crane’s computer, observation of the rigging, and the operator’s feel for how the crane and bucket were responding.
This was also the Trimble crew’s first time operating the clamshell in the field. One of the largest learning curves was understanding how the bucket changed the way the crane reacted throughout the operation, particularly as it transitioned between an empty bucket, contact with the bottom, and a loaded bucket returning to the surface.
The Challenge Started Before the First Pick
Operating the clamshell wasn’t the only challenge. Simply getting the crane to the hydro facility required careful equipment selection.
Access included narrow roads, off-road-style conditions, and a gate opening measuring approximately 10 feet wide. With the crane itself measuring roughly 8 feet 6 inches wide, there wasn’t much room to spare.
The 80-ton crane was selected in part for its maneuverability and all-terrain capabilities, allowing the crew to navigate the site while still providing the reach and capability needed for the underwater operation.
Once positioned, the crane would be working approximately 85 feet from the trash racks.
For this project, equipment selection wasn’t based on capacity alone. Getting the right crane to the work area was part of solving the job.
One Operation Above and Below the Waterline
Because the crane operator couldn’t see the submerged work area, Trimble Services coordinated closely with the commercial divers from Hunt Underwater Specialties.
Before each operation, a diver entered the water and assessed the location of the debris. The diver then returned to the surface and communicated the location to a spotter, who remained in direct contact with the crane operator.
For safety, the diver exited the water before the clamshell was operated.
From there, the spotter directed the operator toward the area identified by the diver. Once the bucket disappeared beneath the surface, the operator relied on the crane’s computer, the behavior of the rigging, and his own feel for the machine to determine what was happening approximately 30 feet below.
One particularly important indication came from the crane’s load information: when the operator saw the weight of the bucket come off the crane, he knew the clamshell had reached the bottom.
From there, the bucket could be closed around the material and the load brought back to the surface.
It was a process built around communication: diver to spotter, spotter to operator, and operator to machine.
How the Two-Line Clamshell Works
Unlike a conventional suspended load, this clamshell operates using two crane lines with separate functions.
One line is used to hoist and control the bucket while it is empty. The second line operates the closing action and raises the bucket once it has collected material.
That two-line arrangement allows the crane to lower an open bucket into the work area, collect loose material, close around the load, and bring it back to the surface.
At Prospect, the combination of the 37-inch clamshell bucket and 60-inch trash rack opening gave the crew the access needed to reach debris that was approximately 30 feet underwater.
The equipment may look simple sitting on the ground. In operation, however, the crane operator is simultaneously managing two lines, monitoring the crane, responding to changing load conditions, and—in this case—doing it without being able to see the bucket.
That made operator experience and communication just as important as the equipment itself.
A New Capability Put to Work
Over the three-day project, the Trimble Services team used the clamshell to remove accumulated logs and wood debris from in front of the trash racks as part of Brookfield’s preventive maintenance work.
For Trimble, the project also demonstrated a new application for our crane fleet.
The same clamshell capability used at Prospect can provide another option for underwater debris-removal applications at hydroelectric facilities, as well as other environments such as marinas and canals where submerged material needs to be reached and removed.
More importantly, the project demonstrated that specialized work isn’t accomplished by equipment alone. It takes thoughtful equipment selection, experienced operators, communication between crews, and the ability to adapt when the work itself is happening somewhere you can’t see.
Our first clamshell operation took us approximately 30 feet below the waterline—and opened the door to another way Trimble Services can help solve difficult access and debris-removal challenges.
A special thank you to Brookfield for the opportunity to support this project and to the commercial divers from Hunt Underwater Specialties for their coordination throughout the operation. Projects like this are a team effort, and we appreciate everyone involved in making this one a success.
Have an Underwater Debris Challenge?
From trash rack and intake areas at hydroelectric facilities to other difficult-to-access underwater environments, Trimble Services can provide crane and specialized equipment support for debris-removal projects throughout New York.
Every site is different. Talk with our team about your facility, access conditions, working depth, and the challenge you're trying to solve.